UNI; if OF CAtl;ORNIA The eye — it cannot choose but see. — Wordsworth. Brain, showing eyes with muscles removed, optic nerves, and chiasm. TECHNIQUE OF EYE DISSECTIONS BY FREDERIC A. WOLL, Ph.D., Associate Professor, Department of Hygiene, College of the City of New York; Optometry Courses, Columbia University; Member of New York State Board of Examiners in Optometry; Honorary Member: American Optometric Association; State Societies — Alabama, California, Connecticut, Kentucky, Maine, Massachusetts, North Carolina, Rhode Island; Local Societies — Lehigh F alley Society of Optometrists, Mahoning Valley Opto- metrists' Society, and Optometrists' Club of Brooklyn. SECOND EDITION NEW YORK FREDERIC A. WOLL 1924 OPTOMETRY LIBRARY COPYRIGHT, 1914, BY FEEDEEIC A. WOLL Printed in the United States of America First Edition, July, 1914 Second Edition, April, 1924 OPTOMETRY LIBRARY SCHLUETER PRINTING CO.. NEW YORK LIBRARY DEDICATION THIS LITTLE BOOK IS DEDICATED WITH AFFEC- TION AND ESTEEM TO MY FIRST TEACHER IN OPTICS, MY FRIEND FOR YEARS ANDREW JAY CROSS WHOSE RESEARCH IN THE FIELD OF APPLIED OPTICS HAS WON FOR HIM RECOGNITION AND HONOR \ A CONTENTS PAGE Preface ... J. - 38 . . 13 Introduction 17 Removal of Hyaloid Membrane with Contents and Attach- ments Intact 25 Canal of Petit, The 35 Interior of the Eye, The 38 Posterior Half , The % . .. .. .. . . :40 Optic Nerve, The .. .. '..,'.. .... ... . . =47 Anterior Half, The .. .. .. f . . " .~. .. .... .:.;:!ili» Iris, The .'....... VMifil Cornea, The >;. .. ..52 Crystalline Lens, The . . 53 Choroid, The 62 Retina, The . • 74 Sagittal or Vertical Section of the Eye, The 86 Papilla, Puncta Lacrimalia, and Nasal Duct, The . . . . 92 Meibomian Glands and Ducts, The 96 Enucleation of the Orbital Contents, The 97 Ophthalmoscopic Examinations .. 106 Lacrimal Ducts, The . . . . . f . . 112 Lacrimal Gland, The ...... 114 Capsule of Tenon, The 115 Superior Oblique Muscle and its Pulley 117 Other Extrinsic Muscles, The 118 Three Tunics of the Eye, the Hyaloid and its Attach- ments, The 120 ILLUSTRATIONS PAGE Brain showing eyes with muscles removed, optic nerves, and chiasm Frontispiece Glassware and tools 22 The first cut 28 How the point of the scissors is kept away from the under- lying tissues 29 Half of the sclerotic separated 30 Picking up the choroid 31 Emptying the eye of its contents 32 Isolated hyaloid, contents and attachments intact . . . . 33 Petit 's Canal 36 Cutting eye into anterior and posterior sections with safety-razor blade 39 Posterior half showing retinal vessels and choroid . . . . 40 Showing network of vitreous 42 Tearing retina away from posterior half of eye . . . . 44 Posterior half of eye with retina removed 45 Excavated posterior half of eye 46 Split optic nerve 47 Ciliary processes and the lens 48 How to pull off vitreous 50 Processus Zonuloe 54 Onion-like layers of lens removed . . 56 Cross section of lens 57 Lenses showing the results of different kinds of treatment 60 Puncturing the cornea 63 Removing the cornea 64 How to separate the choroid from the sclerotic 65 Cutting away the separated sclerotic 67 Scraping the choroid free from the sclerotic 68 The isolated choroid 69 Inserting scalpel to loosen lens and cut through vitreous 70 Ta.king out lens and "core" of vitreous 71 Squeezing out remaining part of vitreous 72 Cutting through the iris 75 Cutting around the ciliary ring 76 11 ILLUSTRATIONS PAGE Lens, iris, and part of vitreous removed 77 How to force blowpipe into the vitreous 78 Bulging out of vitreous caused by blowing air through glass blowpipe 79 Showing vitreous removed 80 Folding the retina by blowing air at it through blowpipe 81 Suspended retina. Sclerotic ready to be cut away . . . . 82 Showing sclerotic nearly all cut away 83 Isolated retina 84 The beginning of the cutting of the eye for sagittal sec- tions 87 Method of cutting through the crystalline lens 88 Cutting through cornea to complete the sagittal sections 89 Sagittal section enlarged 90 Part of calf's head showing knitting needles inserted in puncta 93 Course of knitting needles showing the course of the canaliculi 94 Initial cuts to be made in the skin 98 First cut in bones of orbit 99 All the cuts to be made in bones of orbit 100 How to pry bone loose 101 Dissecting close to bones of orbit 102 Excavated orbit 103 Anterior view of enucleated eye 104 Side view of enucleated eye. All parts in situ 104 Enlarging pupil for ophthalmoscopic inspection . . . . 107 How to get rid of the pucker in the cornea 108 Window cut in the eye . . 110 Pins inserted in lacrimal ducts 112 Capsule of Tenon blown up 115 Showing the extrinsic muscles of the eye 118 Cutting through the iris 120 Scraping ciliary processes free. Choroid cut around ciliary ring 121 Cutting away choroid 122 Three tunics, hyaloid, and lens 123 12 PEE FACE THE aim of this booklet is to present to the eye-specialist, the teacher, the student, and others interested in the study of the anatomy and physiology of the eye, some definite meth- ods to follow in the dissection of that organ. Most dissections of the eye are not made with the same degree of care and skill used in the dissections of other organs. In follow- ing the usual method of dissecting eyes, much of the important detail is lost. Often certain membranes are confounded with others, and wrongly demonstrated. Furthermore, an eye is merely divided by some demonstrators into an anterior and a posterior half, a very short time is spent by the students scrutinizing each half; then the text-book is turned to, and the anatomy is studied descriptively. Not enough time has been given to thorough- ly dissecting all parts of the eye. As much time should be given as is necessary to bring 13 PREFACE out prominently all its parts. Other organs of the body are more thoroughly dissected, and, therefore, the student has better opportunity to gain a clearer comprehension and better un- derstanding of the anatomy and physiology of those organs. Also, as much time should be given, proportionately, to the learning of the technique of the dissection of the eye as is given to the learning of the technique of dis- secting other organs of the body. Many now make a direct specialty of minis- tering to those suffering from errors of ocular refraction, ocular diseases, and ocular reflexes, and for those specialists, principally, this book is written. It is to fulfil its mission to them by acting as a guide and as a complement to the descriptive matter in the text-book. It is sent forth in the hope that it will tend to create more interest in the study of the practical anatomy of the eye. It is written with a de- sire to stimulate the ability to make careful and intelligent observation. It carries with it, as a final end, an earnest wish that it may, in pome small way, be the means of opening up 14 PREFACE to the original researcher, a larger field for the further study of the most important of the senses — the eyesight. Most of the dissections explained in the fol- lowing pages are original; some, however, are only revisions of old methods. This opportunity is taken to acknowledge the many helpful suggestions that were made by Dr. Ivin Sickels, of the College of the City of New York, and by the late Dr. Edward C. Spitzka, of New York. Thanks are due Mr. E. F. Howes, of Messrs. Swift & Co., for fur- nishing the necessary supply of beef eyes; to Messrs. Lee & Beach, photographers, of New York, for their painstaking efforts in pro- ducing good photographs of the actual dissec- tions; and to Schlueter Printing Company, of New York, for their many courtesies and in- terest in the production of the book. FREDEKIC A. WOLL. New York, July 21, 1914. 15 INTRODUCTION IN eye dissections it is unnecessary to have either a large equipment of instruments or a special room. To have a laboratory at one's disposal is but a small added conve- nience. Not to have it, is no serious hindrance. The work may be carried on and successfully done in one's office or in the home, as well as in class-room or laboratory. If it is true that the atmosphere of a laboratory adds zeal to the efforts of a worker, but there is no labora- tory available, then reverse the order; let the zeal of the worker add to the atmosphere of the place in which he is doing his work. Two things, among others to be mentioned later, are essential; a table of convenient height, and a. good light, natural or artificial. Both are but modest needs. Compared with other dissections, there will be found an ab- sence of offensive odors. Neither are there any repulsive sensations experienced. Such experiences are quite common when making 17 INTRODUCTION other kinds of dissections. This work is clean and attractive. Indeed, one may even develop a rather keen sense of the aesthetic. Many of the various parts of the ,eye, when separated and properly preserved, then viewed and inspected, are bound to bring forth ex- clamations of appreciation and wonderment. One can then better understand the state- ment: "When Nature perfected the first eye she took a, day off so she could admire the re- sult of her finest piece of handiwork." This does not imply that dissections of the eye tend to develop art appreciation. Appre- ciation of the wonderful in Nature's construc- tion of the special organs is not, however, to be relegated to a distant point. Such appre- ciation is concomitant with the knowledge that comes from having seen, handled, and examined the object studied. The orchestra leader must have a good lis- tening and hearing ear. This is developed in him because he has to exercise constantly his power of listening and hearing. The dissector who would become proficient in eye dissections 18 INTRODUCTION and in anatomical investigations must have a good seeing eye and a dextrous hand. To ac- quire these two most valuable aids necessary to carry on careful inquiry or research, it is essential to practise using the eye and the hand. Combined with the expertness of these two, must be the ability to continue one's ef- forts in the face of failure ; to redouble one 's efforts to attain success despite the short- comings of eye or hand. This simply means practise and patience. And the one who is without that wonderful virtue, patience, will never stay long enough with his problem to gain either 'an observing eye or an expert hand, or to achieve his end, and thereby reap the full and pleasing results of his efforts. In order of importance, patience really precedes dexterity, skill, arid observation; and persis- tence of effort is a factor not to be entirely outshone by any other virtue. With these at- tributes, knowledge of the subject in hand naturally follows. One reason why eye dissections are easily carried on is because material can always be 19 INTRODUCTION readily procured. Any butcher will furnish sheep, pig, or beef eyes. Or, if one has the time to visit the manager of a slaughter-house, and make known to him one's needs, he will supply enough eyes to carry through a host of interesting dissections and experiments, and give sufficient material for careful, orderly, and fruitful study. Perhaps in no other kinds of dissections will the investigator find so much of interest, or have his efforts crowned with such abundant and satisfactory results, as in the dissections of the eye. But no one should try to study all parts of the eye with only one specimen. To try to do so is an error, and a common one often committed by both teachers and students. Specimens cost little or nothing, and it is no more trouble to pre- pare a half-dozen eyes for dissection than one. The cost of preparation, too, is but little more for a number of eyes than it is for one, and may be no more in some instances. Besides, having enough material on hand saves time in case of a failure. Also, one can quickly repeat a dissection, and so procure any number of 20 INTRODUCTION desired specimens of specific parts, or do over again the same dissection on another eye just for the purpose of practise, and thus add to one's dexterity. It is, therefore, strongly ad- vocated to have plenty of material on hand be- fore beginning work. Economy here is not even " penny wise." The tools, or instruments, needed are but few in number; an ordinary scalpel, a pair of blunt tweezers, or forceps, as they are some- times called; a pair of sharp-pointed tweezers, a pair of small, sharp-pointed scissors of about three to three and a half inches in length, and a pair of large scissors, about four or five inches in length, having one jaw sharp-pointed and one jaw blunt. For glassware, any wide-mouthed jar or bottle, such as the ordinary fruit or jelly jar, will do for preparing material. For clarifying tissues, or for preserving and keeping them, small, wide-mouthed bottles or vials should be used. And for temporary keeping, or for purposes of "running through" various fluids, the regular Stender dishes are most conve- 21 INTRODUCTION nient. A glass graduate is almost indispen- sable if accuracy in measuring fluids is de- sired. (Fig. 1.) The chemicals needed are few in number and small in quantity: Alcohols in varying strength, which can be made by diluting a 95 Fig. 1. per cent, alcohol, and keeping an absolute alco- hol on hand. A few ounces of formaldehyde will make enough solutions of different strengths to be sufficient for the preparation and keeping of many specimens. Of other chemicals, such as xylol and cedar oil, only small quantities are needed; enough to cover 22 INTRODUCTION a specimen. Fifteen to twenty cents worth of each will be an ample supply to keep on hand. All of these may be procured at any large drug store, and are the only chemicals re- quired for doing the dissections as explained in this book. Before further advance is made, it will be best to state that this work deals only with methods for dissecting the various parts of an eye, and is primarily intended to aid in the study of the anatomy and physiology of the eye by being used in conjunction with such books as "Gray's Anatomy," "A Text-Book of Physiology," by Howell, "The Anatomy and the Physiology of the Eye, ' ' by Brown and Zoethout, and similar other works of authority. However, if it is desired to acquire only speci- mens, then, of course, no other works are necessary, and the matter contained herein is sufficient to enable one to procure just what is wanted. It is also wise to state here that since hu- man eyes are hard to procure, and not avail- able in large quantities, one must resort to the 23 INTRODUCTION use of the eyes of animals, which are procur- able in large quantities, and which may be used without "feelings" in the matter. Though there is a difference between the eyes of human beings and the eyes of other ani- mals, the difference is slight and of minor im- portance when compared with the similarity of the more important parts. 24 TECHNIQUE OF EYE DISSECTIONS REMOVAL OF THE HYALOID MEM- BRANE WITH CONTENTS AND ATTACHMENTS INT ACT* t ONE of the easiest and most satisfactory dis- sections to attempt is the isolating of the hya- loid membrane with its contents and its at- tachments. The success one meets with in making this dissection will surely prove a strong incentive for making all the rest. For these reasons this has been placed first in this arrangement. In eye dissections it is quite customary, in giving directions for dissections, merely to *Approved as an original article in The Anatomical Eecord, September, 1912. tThis dissection, and several of the following, appeared in The Optical Journal and Review, beginning- with the issue of January 16, 1913. 25 TECHNIQUE OF EYE DISSECTIONS mention the hyaloid membrane and its rela- tions with other parts of the eye. Rarely is there any attempt made to isolate it. Often, too, the retina is mistaken for the hyaloid, and the retina, then wrongly demonstrated as being attached to the choroid. Of course, it is impossible to separate the hyaloid from the vitreous; but a dissection can be made which, when placed in a glass of some kind, will show the hyaloid. If the following simple tech- nique is carefully observed, the membrane, with all its connections, can be easily sepa- rated from certain other parts of the eye. Opportunity for thorough study and observa- tion will then be made extremely easy. Procure the eye of either a sheep or a bul- ]ock. Instead of following the usual procedure of hardening in any one of the several solu- tions used for the purpose of toughening the ocular tissues, place the eye in a cool place and permit it to collapse a trifle. Usually two or three days is a sufficient length of time to accomplish the result. Experiments have shown that if an eye is 26 TECHNIQUE OF EYE DISSECTIONS too fresh the ciliary processes will not be easily detached from the hyaloid (zonular pro- cesses), and if the eye has been in a preserv- ing fluid, the same result will follow. A sheep's eye will make a, better specimen even if it is small, because the ciliary processes are more easily separated from the zonular pro- cesses. If a bullock's eye is used, it must be left in a cool place a, day or two longer than in the case of a sheep's eye, in order to permit a long enough time to elapse to allow disin- tegration of the eye to take place sufficient to have the two processes separate easily and cleanly. With a pair of dissecting forceps pinch up the sclerotic about 5 mm. anterior to the equa- tor. With a pair of small, fine-pointed scis- sors, make an incision. (Fig. 2.) Next hold the eye in the left hand without exerting any pres- sure. Insert the point of the scissors into the incision which has been made, and cut. Be careful to keep the point of the scissors close to the sclerotic or an untimely puncturing of the choroid will occur. (Fig. 3.) Continue the 27 TECHNIQUE OF EYE DISSECTIONS Fig. 2— Making the first cut. (Page 27.) 28 TECHNIQUE OF EYE DISSECTIONS cutting on a line parallel to the equatorial me- ridian and about 5 mm. anterior to it until about half the sclerotic has been separated. In cutting, always move the point of the scis- Fig. 3 — Showing how the point of the lower jaw of the scissors is to be kept away from the underlying tissues. (Page 27.) sors forward with a slight oscillating lateral movement. (Fig. 4.) While doing this, partly suspend the eyeball from the point of the scis- sors. Doing these things will tend to loosen 29 TECHNIQUE OF EYE DISSECTIONS the choroid from the sclerotic and prevent puncturing too soon the former mentioned membrane. Now apply pressure in such a Fig. 4 — Showing about half of the sclerotic separated. (Page 29.) manner that the lips of the cut sclerotic will gap. Into this put the point of the scissors and very carefully pick up the ehoroid and the retina with the point of the scissors and cut 30 TECHNIQUE OF EYE DISSECTIONS them. (Fig. 5.) If the choroid alone has been picked up and separated, the retina will show milky white or yellowish white underneath. The retina must then also be separated. Care Fig. 5. — Picking up the choroid with the point of the scissors. must be taken not to go deeper than the retina or the hyaloid may be damaged. Continue the cutting of the choroid and the retina for a distance of about 20 mm. Apply enough pres- sure occasionally so that the vitreous will be 31 TECHNIQUE OF EYE DISSECTIONS forced upward and above the cut choroid and the retina. This will show whether any strands of the two membranes have been left Fig. 6— A. Hyaloid, vitreous, and lens ready to drop out of the eyeball. ' uncut. If the separation is complete for the distance specified above, invert the eyeball, squeeze and shake gently over some receptacle, such as a Stender dish, three-fourths filled 32 TECHNIQUE OF EYE DISSECTIONS with a 2l/2 or 5 per cent, solution of formalde- hyde, and the hyaloid membrane containing the vitreous, its attachments, suspensory lig- A Fig. 7 — Photograph of dissected hyaloid mem- brane (A), with pigmented indentations of the ciliary processes, the suspensory ligament (B), and the crystalline lens in its capsule (C). (Page 34.) ament to the lens capsule, and lens, will drop out intact, as when one empties the contents of an egg. (Fig. 6.) Many times a considerable amount of pig- ment from the second tunic will remain at- TECHNIQUE OF EYE DISSECTIONS tached to the processus zonuloe. This pigment may be easily removed by scraping it off with the sharp edge of the scalpel or by brushing it off with a soft, wet tooth-brush. It is unwise to use alcohol as a preservative because it produces an almost immediate opaqueness and hardness which spoils the specimen for further study. This description may give the impression that the dissection is a lengthy one; however, it can be done by an expert in two or three minutes; by a beginner in five or six minutes. For purposes of demonstration or study the specimen should be placed in a small bottle or a vial containing a 5 per cent, solution of formaldehyde. It can then be examined with hand lens or microscope. (Fig. 7.) 34 THE CANAL OF PETIT THE canal of Petit is a "triangular space around the circumference of the lens." That it can be "inflated through a fine blowpipe in- serted through the suspensory ligament, " is the usual direction given. However, the ordi- nary "fine blowpipe" is much too large and too dull to be inserted through the suspensory ligament. Take a long medicine-dropper (5 or 10 cents at a drug store), or a pipette, and heat it until it is red hot over an alcohol lamp or a Bunsen burner; hold one end with one hand and the other end with a pair of tweezers. As the glass becomes white hot pull the tube apart. This will leave the places of separation pointed and sharp-edged. Use the larger of the two pieces. Sometimes the point or tapering end of the tube is too long and the bore too small. All that is necessary is to first mark off with a file the length to be broken off, and then that length may be snap- 35 TECHNIQUE OF EYE DISSECTIONS ped off, leaving a sharp-edged, tapering point. After having completed the first dissection (the hyaloid, contents and attachments), and the specimen has been in the formaldehyde Fig. 8 — A. Glass blowpipe. B. Petit 's canal. solution for ten days or two weeks, it will have become hard and tough enough to stand a considerable amount of rough handling. If the specimen has been kept in a large recepta- cle, such, for instance, as a jar, remove it with 36 TECHNIQUE OF EYE DISSECTIONS a spoon; if in a small jar or vial, empty out the fluid, then slide the specimen out on what- ever has been prepared to receive it. Turn it so that the lens will be uppermost. Find the suspensory ligament in the Zone of Zinn. In- sert the pointed end of the glass tube, close to the lens, and blow gently until the canal shows its sacculated construction by filling with air, giving the appearance of a lot of little bubbles surrounding the periphery of the lens. (Fig. 8.) It may be necessary to move the blow- pipe in and out in order to find the canal, all the while blowing steadily through the tube. THE INTERIOR OF THE EYE FOR the study of the interior of the eye and its contents in situ either a fresh or a har- dened eye will do; a hardened eye is prefer- able. In the dissection for isolating the hya- loid membrane, vitreous, lens, and other parts, the anterior and posterior halves of the evacu- ated eye may be separated entirely, and each half studied. However, the choroid and the retina will be more or less mutilated, and the vitreous and other parts will be removed. The absence of these parts will prevent one from receiving a definite idea of their anatomical relationships. Therefore, it is better to work with an entire and complete eye. Remove all the muscles and fatty tissues from the outside of the globe; then cut it in half through the equator, thus dividing it into an anterior and a posterior half. The cutting of the sclerotic, as well as the underlying tis- sues and the vitreous, should be done with the 38 TECHNIQUE OF EYE DISSECTIONS large scissors; using a knife or scalpel will tend to disturb the positions of those tissues or so tear them that they will not be of much Fig. 9 — Showing method of cutting eye into anterior and pos- terior sections with safety -razor blade. use for purposes of study. An ordinary safety- razor blade makes an excellent instrument for separating the eye into two halves, because it cuts through the tissues without tearing them in any way. (Fig. 9.) The rather dark col- 39 TECHNIQUE OF EYE DISSECTIONS ored, viscid fluid that escapes when the eye is halved is the perichoroidal lymph, not the aqueous, as is sometimes stated. THE POSTERIOR HALF The posterior half is taken first because it Fig. 10 — The retina, retinal vessels, and iridescent choroid showing through the vitreous. is the simplest and easiest of the two halves to dissect. In this half of the eye the retina may be readily seen through the vitreous ; the choroid and its apparent iridescent colors through both vitreous and retina. (Fig. 10.) 40 TECHNIQUE OF EYE DISSECTIONS Remove the vitreous by simply tilting this half of the eye, and with the finger push out the vitreous. Sometimes the vitreous will adhere very closely to the retina. This occurs especially when the eye has been in formaldehyde for a long time. In such a case the removal of the vitreous without injuring the retina requires patience and care. The use of the scalpel and the scissors may become necessary. Another very good way to remove the vitreous is to take hold of the sclerotic, turn it so that the vit- reous is downward, and then shake gently until the vitreous separates itself from the retina and, drops out. After the vitreous has been removed, notice its glassy appearance; hence its name — hyaloid body. Try to pull it apart with the fingers, and it will be noticed that it seems to be held together by more or less of a network of fibres. (Fig. 11.) Whichever method for removing the vitreous is followed, the retina will be left rather badly wrinkled and] out* of place. If the last-men- tioned method, which is really the best of the 41 TECHNIQUE OF EYE DISSECTIONS three described, is the one adopted, the retina will be left in an entirely collapsed and folded form. In any case, to straighten out the ret- Fig. 11 — Showing how vitreous seems to be held together by a network of fibres. (Page 41.) ina against the choroid, immerse the whole posterior half in water, inside uppermost. The retina will then slowly unfold itself and lie flat against the choroid. With the tweezers re- 42 TECHNIQUE OF EYE DISSECTIONS move the whole half from the water ; tilting it slowly to empty it of all the water, and, having done so, turn it idown upon the table rather forcibly in order to help it drain itself of all the water. Notice the thinness of the retina, and, also, that the seeming iridescence of the choroid shows through. The optic disc, which is the point of entrance of the optic nerve, and the optic cup are easily recognized, though neither will be seen us large as when viewed in the living eye with an ophthalmoscope. The blood vessels of the retina, as they ramify outward or forward, after their entrance through the optic nerve through which they pass, are also very plainly seen. A closer inspection will show, in the very centre of the " entrance " of the optic nerve, a whitish, pointed vessel, about 1 or 2 mm. long. That is the sloughed-off and atrophied end of the hyaloid artery, which, when the eye was in an embryonic state, ran forward from the central artery of the retina through the hyaloid canal to the posterior surface of the 43 TECHNIQUE OF EYE DISSECTIONS lens. With the forceps pick up the peripheral edge of the retina, and, by pulling gently up- ward, tear it away from its apparent place of Fig. 12 — Picking up the retina in order to tear it away from the entrance of the optic nerve. attachment to the "entrance" of the optic nerve. (Fig. 12.) When this has been done, there will be seen some threads protruding 44 TECHNIQUE OF EYE DISSECTIONS from the optic nerve. Filling the half with water will tend to separate these strands, which are optic-nerve elements. After the removal of the retina, the iri- descence of the choroid (tapetum lucidum) Fig. 13 — The lighter area is the field of iridescence of the choroid. (Fig. 13) may be examined with a, hand lens, or, after its, removal, a piece may be cut and placed under a microscope. This irides- cence is, of course, not present in the human 45 TECHNIQUE OF EYE DISSECTIONS eye. ("Physiology of the Senses," McKen- drick & Snodgrass, page 101.) After the choroid is removed, which is ac- complished in the same manner that the retina is removed, the inner side of the sclerotic is Fig. 14 — Excavated posterior half of the sclerotic. laid bare to view. The brownish color is mostly due to the presence of a small amount of pigment in the cells of one of the inner lay- ers, it is also due, to a slight extent, to the staining influence of the perichoroidal fluid. (Fig. 14.) 46 TECHNIQUE OF EYE DISSECTIONS THE OPTIC NEKVE The excavated posterior half may be used now to show and .to study the construction of the optic nerve. In cutting the optic nerve away from the sclerotic leave at least 5 mm. of Fig. 15 — Enlarged to show the entrance of the optic nerve. (Page 48.) the sclerotic attached. It will make handling easier. With the thumb and forefinger of the left hand hold the nerve in such a way on the table that it will be straightened out length- wise, and then, using the scalpel or a safety- 47 TECHNIQUE OF EYE DISSECTIONS i • razor blade, the latter being preferable, cut the nerve in two longitudinally. (Fig. 15.) The cutting must be done with one movement, otherwise the nerve will be hacked, and will not make a good specimen. This specimen Fig. 16 — Showing ciliary processes and crystalline lens. will show the way the nerve fibers are ar- ranged. A cross section should be cut from the optic nerve of another eye, and then the two sections should be compared. The cross section will show the sheath of the nerve a 48 TECHNIQUE OF EYE DISSECTIONS little better than will the longitudinal section. In cutting the longitudinal section, one is sometimes so fortunate as to cut through the central blood vessels of the retina, These ves- sels will show up then as a rather thin dark streak about 5 or 6 mm. long. THE ANTERIOR HALF The anterior half will show the lens in situ, the ciliary processes, the posterior aspects of the iris and the lens, the corona ciliaris, the orbicularis ciliaris, and the ora serrata, (Fig. 16.) If the eye has been cut in two too far forward of its equator, the ora, serrata will not be present. The ciliary processes and pos- terior aspect of the lens may be seen to better advantage when the anterior half of the vit- reous is removed. This is done with the dull- pointed tweezers, by c'atching hold of the vit- treous at any part of its free or cut margin, and stripping it off both the ciliary processes and the lens, using a prying, pulling movement to do so. (Fig. 17.) The two layers of the pig- ment cells, pars ciliaris retinae, which cover 49 TECHNIQUE OF EYE DISSECTIONS the inner surface of the processes, may be re- moved by picking them away carefully with the tweezers. The processes then will be seen to be a whitish color. The pupillary edge Fig. 17 — Anterior half, showing how to pull off vitreous. (Page 49.) of the iris rests upon the capsule of the lens, but the nearer the approach is to the choroidal edge the farther the iris is from the lens ; thus are formed the anterior and the posterior chambers of the eye. The dissection of the sagittal section of the eye, explained further 50 TECHNIQUE OF EYE DISSECTIONS on, will show these two chambers in section. One will gain a much clearer conception of their construction in that section than in the "anterior half " specimen. Now, remove the lens, using the point of the scalpel to cut through the suspensory liga- ment close to the lens. When this has been done there will be seen in the anterior cham- ber a thin, watery liquid — the aqueous humor. The corona ciliaris and orbicularis ciliaris may be better seen and studied if viewed through a hand lens. THE IRIS To see the iris, take hold of the cut edge of the dhoroid, and, gently pulling, separate it from its attachment to the corneo-scleral junc- tion. The white ring on the anterior surface of this part of the second coat of the eye is the ciliary ring. With a scissors, cut around this ciliary ring at its outer edge. This speci- men will show the anterior surface of the iris, and on the posterior side it will show the close relationship between the iris and the ciliary 51 TECHNIQUE OF EYE DISSECTIONS processes. A hand lens will help greatly to bring -out the very interesting fine points. THE COKNEA After the. anterior portion has had every- thing removed from it there will be left nothing but the first coat or tunic of the eye —the anterior portion of the sclerotic and the cornea, The way the cornea seems to fit into the sclerotic is not quite as one is led to believe when told that it fits into the sclerotic much the same way in which a watch crystal fits into a watch.* Holding this part of the eye up to a strong light one will see that the sclerotic seems to overlap the cornea in the vertical axis. By using the tweezers the cornea may be split. Nothing in the way of locating its layers can be recognized, however, unless a section is made for microscopic examination. The epi- thelial may be scraped off when the cornea is a trifle dry. This is the ocular epithelium re- duced to a layer of flattened cells. * ' ' Anatomy and Physiology of the Eye, ' ' Brown & Zoethout. 52 TECHNIQUE OF EYE DISSECTIONS THE CKYSTALLINE LENS If the preceding dissections have been done, the crystalline lens will already have received some notice. To study the lens properly one should use an eye that has not been hardened and also an eye or the lens of an eye that has been in a 5 per cent, solution of formaldehyde for about two weeks. The lens in the unhardened eye will prove too friable to permit much handling. The dis- section should be made, however, in order to give opportunity to notice the crystalline clear- ness of the lens substance, its great magnify- ing power, its attachments, its capsule, etc. For this purpose it is necessary to proceed only as in the dissection for the "hyaloid mem- brane, etc/' That is, use an eye that has been kept in a cool place for several days, and then open it, and remove hyaloid, vitreous, and lens intact, as in the first dissection taken up in this book. To examine the specimen in de- tail, turn it so the lens will be uppermost. (Fig. 18.) To remove the lens it is necessary to sepa- 53 TECHNIQUE OF EYE DISSECTIONS rate the suspensory ligament, using for this purpose the small-pointed scissors. The cap- sule may be removed by picking it up on the periphery of the lens, and stripping it off. It will peel off about the same way that the outer skin of a bean or pea does. Fig. 18 — Enlarged to show the processus zonuloe. (Page 53.) The tri-radiate lines on the posterior and the anterior surfaces of the lens will not be as clearly discernible as in the lens coming from the hardened eye. Close inspection and the use of a hand lens will help bring them out more clearly. Now, with the point of the scalpel try to separate the outer layers (cortex) from the 54 TECHNIQUE OF EYE DISSECTIONS harder inner layers (nucleus). This will not prove very successful but is suggested for the purpose of comparison when the same thing is done to the hardened lens. It will be found that the lens after having been in the formaldehyde solution is no longer crystal like, but more or less translucent. When viewed from either the anterior side or the posterior side, the tri-radiate lines on each surface will be seen to begin at the poles of the lens and radiate outward toward the lens equator. Holding the lens up to a strong light will show that though the lines on either surface form angles of 120 degrees, the angles formed by the lines on one side with the lines on the other side are 60 degrees. On the an- terior surface of the lens the vertical line ex- tends upward from the pole; on the posterior surface downward from the pole. To study the laminated structure of the lens, it is best to boil the lens. The best way to do that is to drop the lens from either a hardened or unhardened eye into boiling water. Let it boil in the water for about two and a half to 55 TECHNIQUE OF EYE DISSECTIONS three minutes. Longer than that time will cause the lens to be put out of shape, and make it so fragile that it can no longer be handled without having it fall apart. If the lens comes from an unhardened eye it might be best to boil it not more than about two minutes. Fig. 19 — Showing the way the onion-like layers of the lens may be peeled off. Insert the point of the scalpel carefully at one of the poles, and lift gently in the direc- tion of one of the radiating lines. This will tend to raise one of the concentric layers, which can be easily peeled off. Eepeat this in the direction of the other two radiating lines. Examining, with a hand lens, the exposed sur- 56 TECHNIQUE OF EYE DISSECTIONS faces and the layers, as they are taken off, will show the arrangement of the lens fibres, and will also show plainly their directions. (Fig. 19.) To get another view of the onion- like layers of the lens, cut through it with a Fig. 20 — Section through lens show- ing its concentric layers. safety-razor blade, either longitudinally or equatorially. (Fig. 20.) The better way is to have enough lenses to make one of each kind. Never try to work with only one piece of material. If the lens is first stained with chro- mic acid the layers may be seen better, or, a simpler way is to drop the lens, before cutting it in two, into a, carmine solution; red ink slightly diluted, will do. A lens that has been boiled and partly dis- 57 TECHNIQUE OF EYE DISSECTIONS sected may be placed in a, 5 per cent, formalde- hyde solution, and kept indefinitely. The lens fibres, concentric layers, and lens laminae in such a specimen will always be interesting. A lens that has lost its transparency be- cause of hardening in formaldehyde or boiling may be made clear and nearly transparent again in the following way: First: Place the lens in a 50 per cent, alcohol for several hours. Second : Remove the lens, and let it drain on a piece of blotting-paper; then place it in a 75 per cent, alcohol. Third: Eemove the lens, as before, then place it in an 85 per cent, alco- hol. The lens may be left in this alcohol from ten to twelve hours, after which length of time it should be removed and drained. Fourth: Place the lens in an absolute alcohol, and leave it there for ten or twelve hours. Several hours longer will not injure the lens, nor interfere with the success of the work. Fifth: Remove the lens from the absolute alcohol. Place it upon a piece of blotting-paper, moving it to another place on the blotting-paper whenever the paper around the lens seems to have taken 58 TECHNIQUE OF EYE DISSECTIONS up as much moisture as it can hold. Be sure that the lens has given up nearly all, if not all, moisture. "Kunning through the alcohols/' as this process is called, is for the purpose of dehydrating the tissue. It will be on the side of safety to let the lens lie exposed on the blot- ting-paper for an hour. Sometimes, if the capsule has not been removed, a small quan- tity of alcohol will remain between the lens and the inner surface of the capsule. This must be removed. It may be done by either puncturing the capsule with a pin or needle, and squeezing out the fluid, or by removing the capsule entirely. The latter is preferable. Now drop the lens into xylol. Benzine will answer, though it will not produce quite so clear a lens as the xylol does. At the end of 24 or 36 hours the softer cortex will show quite clear, while the harder nucleus will be still cloudy. At the end of a week the whole lens, if it is a small one^-pig, calf, sheep — will have become quite clear and transparent; if from a beef eye it will take longer. It sometimes takes nearly two weeks. In the case of a boiled lens 59 TECHNIQUE OF EYE DISSECTIONS it will take much longer to clear; it may take a month. Cedar oil may also be used for the purpose of clarifying or "clearing" the lens. Harden in the usual way, run through the alcohols, and ABC D Fig. 21. A. Lens hardened in formaldehyde. B. Lens hardened in formaldehyde, run through the alcohols, and cleared in xylol. C. Lens hardened in formaldehyde, run through the alcohols, and cleared in cedar oil. D. Boiled lens. then place in cedar oil. The oil, however, will stain the lens a yellowish brown, and the lens will not be as transparent and clear as when xylol is used. The longer a lens is left in either of these two clarifying fluids the harder and smaller it will become. At the end of a month or six 60 TECHNIQUE OF EYE DISSECTIONS weeks the lens will have become so hard that it can no longer be cut through with a knife. If it is desired to halve it, a scroll saw will be found to be the best thing to use for this purpose. (Fig. 21.) til THE CHOEOID SELECT an eye that has had a long part of the optic nerve left on it and place it into a 5 per cent, solution of formaldehyde. Leave it in that solution for from, two to three weeks. That period of time in the fluid will be sufficient to permit the choroid to become sufficiently toughened and hardened. Leaving it in the solution longer than that length of time will not injure the eye in any way. After having removed the eye from the formaldehyde, wash it for a few moments in running water. This will remove the preserv- ing and hardening fluid from the surface, and will save the hands a little from the effects of the fluid. Next remove all the muscles and fatty tissues from the sclerotic. After that has been done, puncture the cornea with the pointed jaw of the scissors about 2 mm. from the corneo-scleral junction. (Fig. 22.) Then proceed to cut the cornea away, being 62 TECHNIQUE OF EYE DISSECTIONS careful not to lacerate the choroid or the iris. (Fig. 23.) The escaping aqueous humor will flow over the eye and make it very slip- pery, and, therefore, difficult to hold. Dip the I! f Fig. 22 — Showing how to puncture the cornea. (Page 62.) eye in water, wash it, and then take it out and thoroughly dry it with a cloth. This procedure is absolutely necessary, and, if omitted, will surely result in the dropping of the eye about 63 TECHNIQUE OF EYE DISSECTIONS the time the work on the specimen is nearly finished. Insert the scalpel between the peripheral edge of the exposed iris and what Fig. 23 — Eemoving the cornea. (Page 63.) is left of the cornea, With the back edge of the scalpel, gently loosen the choroid from the inner side of the corneo-scleral junction to 64 TECHNIQUE OF EYE DISSECTIONS which part it is not securely attached. (Fig. 24.) This requires only ordinary care, and but little skill other than that necessary to always Fig. 24 — Showing method of inserting the scalpel to separate the choroid from the sclerotic. keep the scalpel close to the inner surface of the sclerotic. When the choroid-iris edge has been detached from the inner side of the cor- 65 TECHNIQUE OF EYE DISSECTIONS iieo-scleral junction, the weight of the con- tents of the second tunic will cause it to sag and give opportunity to easily separate, with the back edge of the scalpel, the choroid from the sclerotic for about a distance of from 8 to 10 mm. It has been the method in the past to force water through a blowpipe between the scle- rotic and the choroid, in order to separate the attachments. It has also been the method to work under water when wishing to expose or isolate either the choroid or the retina, It is unnecessary to do either of these two things. When the sclerotic has been loosened from the choroid for about 10 him. back from its cut edge around the eye, carefully cut the loosened part away. (Fig. 25.) Then loosen the choroid as far back as to within 1 cm. of the optic nerve. Cut the separated sclerotic away. It will be well to state here that during this dissection the specimen should not be lifted from the table. Keep the eye resting on the table all the time, and never lift it by holding it suspended from the optic nerve. 66 TECHNIQUE OF EYE DISSECTIONS Loosening the choroid from the sclerotic up to this point is a very easy matter; ordinary precaution is all that is necessary to prevent Fig. 25— Cutting away the sclerotic after it has been loosened from the choroid, as shown in Fig. 24. puncturing the choroid with the scalpel, just be sure to remember to keep the point of the scalpel close to the sclerotic. 67 TECHNIQUE OF EYE DISSECTIONS To remove the remaining part of the first coat is a little more difficult, and needs a little more care. Hold the optic nerve in the left hand, and pull it so that the sclerotic will pull Fig. 26. — Showing how to scrape the choroid free from the sclerotic near the optic nerve. away from the choroid. Then, using the cut- ting edge of the scalpel, scrape the choroid loose from the sclerotic close up to the en- trance of the optic nerve. (Fig. 26.) Do not 68 TECHNIQUE OF EYE DISSECTIONS separate the opic nerve from the choroid. Cut away the remainder of the sclerotic close Fig. 27 — Showing the choroid, the optic nerve still attached, the ciliary ring, and the ciliary nerves. up to the optic nerve and the choroid will be free. (Fig. 27.) To get a perfect specimen and completely isolated choroid, it must be emptied of its con- tents. Insert the scalpel between the lens 69 TECHNIQUE OF EYE DISSECTIONS and the iris, force it on through, and in such a manner as to keep the scalpel close to the ciliary processes. (Fig. 28.) Cut the vitreous around the processes. Push the scalpel fur- ther into the vitreous, and cut out the central Fig. 28 — Showing method of inserting scalpel in order to loosen the lens and cut through the vitreous. part of it, just as one would cut out the core of an apple. (Fig. 29.) Eemove the scalpel, pick out the lens and the cut centre of the vitreous with the broad-point tweezers, holding the choroid a trifle suspended by the optic- nerve. The remaining part of the vitreous may be broken down by cutting with the scalpel, and 70 TECHNIQUE OF EYE DISSECTIONS by squeezing and crushing with the fingers of both hands. (Fig. 30.) The choroid will be tough enough to stand this treatment provided Fig. 29 — Taking out the lens and "core" of the vitreous. the pupil is left clear and open to prevent inter-choroidal pressure. After the vitreous has been removed the choroid will be left in a greatly collapsed condition. Dropping it into 71 TECHNIQUE OF EYE DISSECTIONS water and letting it fill up will make it resume its original shape immediately. The retina does not always come out with the vitreous. Fig. 30 — Showing how to squeeze out the remaining part of the vitreous (A) from the choroid, (Page 71.) In such a case, the tweezers may be used to pick out the retina when the choroid is in a collapsed condition. 72 TECHNIQUE OF EYE DISSECTIONS This specimen will show the vena vorticosa, the ciliary nerves, and their way of ramifying, and the long ciliary arteries, which run oppo- site each other and which may be recognized by their rather colorless, tubular appearance. The evacuated choroid makes1 an excellent specimen and one easily examined. Place it in a 3 per cent, solution of formaldehyde, and then examine with a skiascope, an ophthalmo- scope, or by "oblique illumination. " This dissection is wholly original, and may be done in about five minutes. The old tech- nique for doing it required at least an hour of time with the possibility of procuring one perfect specimen in every six or seven. The technique as given here will make it possible to do the work in not longer than five or six minutes for the beginner, and about four min- utes for the expert. 73 THE EETINA ISOLATING the retina from the other tissues requires considerable patience and dexterity. When the retina has been removed and placed in a special receptacle, it will be found that the specimen is well worth the little amount of time spent in making it. Previous techniques, even the writer's own, sometimes took nearly two hours to do, and rarely was the retina isolated without puncturing or tear- ing it; perfect specimens were almost impossi- ble. The following method will assure one of success in nearly every instance. Failures are almost impossible. Punctures, perforations, tears, etc., are rare. The beginner should isolate the retina in about six to seven min- utes; the expert in about four and a half to five minutes. Select an eye with a long optic nerve, and prepare it for this dissection by placing it in a 10 per cent, solution of formaldehyde for 74 TECHNIQUE OF EYE DISSECTIONS Fig. 31 — Cutting through the iris. (Page 77.) about ten to fourteen days, but no longer. If it is left in the hardening fluid longer than that length of time, it will interfere with the easy removal of the vitreous. 75 TECHNIQUE OF EYE DISSECTIONS The first part of this dissection is the same as the beginning of the dissection for the isolation of the choroid. Eemove all the out- Fig. 32 — Showing how to cut around the ciliary ring. (Page 77.) side tissues first, and then the cornea, and about 10 mm. of the sclerotic, as described in the preceding dissection. (See Figs. 22, 23, 24,; and 2&.) That will lay bare the iris and a few millimetres of the choroid. 76 TECHNIQUE OF EYE DISSECTIONS After that has been done, turn the eye so the iris will be uppermost. With the tweezers pick up the pupillary margin of the iris, and with the fine-pointed scissors cut through the Fig. 33 — Lens, iris, and part of vitreous removed. (Page 78.) iris and the ciliary processes (Fig. 31) ; sep- arate both from the choroid by cutting close to the posterior edge of the processes. (Fig. 32.) In doing that, cut partly through the vitreous also, but be careful not to injure the peripheral edge of the retina — ora serrata, After the iris has been separated from the choroid, cut completely through the vitreous 77 TECHNIQUE OF EYE DISSECTIONS Fig. 34 — Showing how to force glass blowpipe (A) into vitreous (B). (Page 80.) in such a way that the lens will also be removed with the iris. (Fig. 33.) Holding the eye suspended by its optic nerve, force the glass blowpipe through the vitreous until it all but touches the posterior 78 TECHNIQUE OF EYE DISSECTIONS Fig. 35 — Showing bulging out of vitreous caused by blowing air through glass blowpipe. (Page 80.) 79 TECHNIQUE OF EYE DISSECTIONS part of the retina (Fig. 34) ; blow gently at first, increasing the pressure until the vitreous suddenly bulges outward. (Fig. 35.) If the iris has been cut away close to the ora serrata, Fig. 36 — Showing the vitreous (A) removed. the vitreous will not only bulge forward, but it will fall out. If, however, it does not detach itself at once, insert the scalpel close to the choroid and with its flat side press downward 80 TECHNIQUE OF EYE DISSECTIONS Fig. 37 — A. Showing retina folded upon itself by blow- ing air at it through the glass blowpipe. (Page 83.) until a separation occurs. Do not let the vitreous drop out too suddenly, because it may tear the retina, Let the vitreous detach itself slowly by the force of its own weight, though it will be well to hold some of its weight on the scalpel. (Fig. 36.) 81 TECHNIQUE OF EYE DISSECTIONS After the vitreous has been removed, turn the eye upward, and by blowing strongly through the blowpipe at the marginal edge of m i Fig. 38 — A. Showing folded retina suspended from its attach- ment, so sclerotic and choroid may be easily cut. away. (Page 83.) the retina, turn the retina upon itself. Eepeat this until the retina lies in a small wrinkled lump at the " bottom " of the posterior part 82 TECHNIQUE OF EYE DISSECTIONS of the eye. (Fig. 37.) Invert the eye (Fig. 38) and cut away both the choroid and the sclerotic close to the optic nerve. No care need be Fig. 39 — Showing the sclerotic nearly all cut away. taken in doing this until the scissors come close to the optic nerve. (Fig. 39.) After the choroid and the sclerotic have been cut away, drop the retina into some 83 TECHNIQUE OF EYE DISSECTIONS water, and it will slowly unfold itself by "bal- looning" out into a perfect and beautiful specimen. (Fig. 40.) But, if it is desired to study the specimen closely, it is better to sus- pend it in a jar or bottle made of thin glass, Fig. 40 — Isolated retina, with optic nerve attached. and containing a 5 per cent, solution of formal- dehyde. Eemember that the retina is a deli- cate membrane in any state; the slightest rough handling may cause it to be torn, or otherwise damaged. If the vessel, in which 84 TECHNIQUE OF EYE DISSECTIONS the specimen has been placed and suspended, has enough preserving fluid to completely fill it, and it is firmly stoppered, the whole thing may be inverted, and turned in any direction, even abruptly, without fear of damaging the retina, This way of keeping the retina will give opportunity to inspect and study the inside as well as the outside of the membrane ; the blood-vessels, and other important parts easily recognized. 85 THE SAGITTAL OR VERTICAL SECTION OF THE EYE PLACE an eye in a 5 per cent, solution of formaldehyde for about two weeks. If the eye is kept in that solution longer than that time, the lens is apt to become so hard that in cut- ing it the capsule and suspensory ligament will be torn, and the lens will then become detached; if for a shorter space of time, the lens and other tissues will be so soft that all may be so badly torn or lacerated, that a per- fect specimen will not be possible. It sometimes happens that in keeping a number of eyes together in a vessel for the purpose of hardening them in the formalde- hyde solution, the corneas of some will be crushed in. For this dissection, select an eye that has the cornea, in perfect condition. Remove all the outside tissues with the scissors, being particular to have the region immediately surrounding the optic nerve per- 86 TECHNIQUE OF EYE DISSECTIONS fectly clear and clean. If the optic nerve is longer than 5 mm., cut it off to that length. To cut the eye in two, use a safety- razor blade; never a scalpel. The latter is too thick, Fig. 41 — Showing the beginning of the cutting of the eye for sagittal sections. too dull, and too clumsy a tool. Begin by cut- ting through the optic nerve; dividing it as nearly as possible into halves. (Fig. 41.) Con- tinue cutting through the sclerotic and all underlying tissues, stopping at the corneo- scleral junction, but do not, during this pro- 87 TECHNIQUE OF EYE DISSECTIONS cedure, even touch the lens. After the eye has been thus partly separated into, as nearly as possible, two equal parts, lay it down upon Fig. 42 — Showing method of cutting through the crystalline lens. the cornea, and, holding the razor blade in the forefingers and thumbs of both hands, cut the lens in two by forcing the blade down through it. (Fig. 42.) Partly open the cut eye to allow one jaw of the large scissors to enter, turn the eye over so the cornea will rest on that 88 TECHNIQUE OF EYE DISSECTIONS jaw, and then cut through the cornea, (Fig. 43.) The two specimens may be kept indefinitely by placing them in a 3 per cent, formaldehyde solution. It will be well to remove the lens Fig. 43 — Showing method of cutting through the cornea and completing the two sagittal sections. from one of the specimens, because it will give better opportunity to see the anatomical rela- tionships. Also, these specimens should be mounted, one above the other, between two pieces of glass, before placing them in the receptacle that is to hold them. TECHNIQUE OF EYE DISSECTIONS Much can be studied in such specimens. Moreover, they present to view the various parts of the organ of vision in such an im- Fig. 44 — Sagittal section enlarged. pressive way, that one does not soon forget the wonderful appearance of the construction of this, Nature's perfect camera. (Fig. 44.) If another eye is cut into two parts, addi- 90 TECHNIQUE OF EYE DISSECTIONS tional interesting specimens may be procured; for instance, one showing the presence of the second coat only, the retina having been torn out. Another good specimen may be made by removing all of the inner tissues, and leaving only the sclerotic and cornea. This specimen will show that the first coat is almost entirely a coat which affords strength and protection to the parts that lie within. THE PAPILLA, PUNCTA LACRIMALIA, AND NASAL DUCT THE only way to dissect the lacrimal appara- tus, other ocular accessories, and the extrinsic muscles, is to procure the head of some animal, preferably a calf's head, because of its size. Any butcher will supply one for from forty to sixty cents. Have the lower jaw removed. It will make a less bulky piece of material to handle. Close to the inner canthus, on the inner side of each lid, will be found a little rounded eminence — lacrimal papilla — in the centre of which is a small opening — punctum lacrimalis. Both may be seen better on the lower lid, if it is pulled down, and on the upper lid, if it is pulled up. Be supplied with two knitting-needles. Take one, lubricate its full length with a little vaseline, lard, oil, or any other lubricant. Insert the needle into the punctum of the 92 TECHNIQUE OF EYE DISSECTIONS lower lid, and push it downward and forward, liming to come out in the nose a short dis- tance from its end. At first it may be a little Fig. 45 — Showing only a part of a calf 'a head and the knitting- needles inserted in the puncta. (Page 94.) difficult to get the needle started; if so, just wiggle the needle, pushing it at the same time as directed, until the nasal duct is found. Do not remove the needle. To insert the other 93 TECHNIQUE OF EYE DISSECTIONS needle into the punctum of the upper lid is rather difficult; for that reason the punctum of the lower lid was chosen first. Grease the Fig. 46. needle, as was done to the first one, and, with a little patience and careful manipulation, the canal opening and its course will soon be found. The needle may then be pushed through until it meets the first one. (Fig. 45.) 94 TECHNIQUE OF EYE DISSECTIONS From the puncta lacrimalia to the place of meeting of the two needles, marks the course of the two canaliculi and their junction before they merge and form the nasal duct. Leave the needles where they are, and begin cutting away the skin. The needles will then mark the course of each canal and the duct very plainly. With the small scissors the canals and the duct may be loosened from the sur- rounding tissues. Or, the scalpel may be used to lay open the canals, cutting along over the top of the needles. (Fig. 46.) The cilia, palpebrae, palpebral conjunctiva, ocular conjunctiva, and other superficial ocular accessories may be examined without dissec- tion. 95 TECHNIQUE OF EYE DISSECTIONS MEIBOMIAN GLANDS AND DUCTS AN examination of the eyelids will show the openings of the ducts of the meibomian glands a short distance back of the cilia. Very fine pins or needles that have been greased may be easily inserted for a short distance into the ducts, and then a dissection made along the course of the duct as outlined by the presence of the inserted pins or needles. Another way to see the glands is to slice through the ducts, with the scalpel or safety-razor blade, the entire width of either eyelid. This will sepa- rate the glands into two parts and show their length, breadth and structure. 96 ENUCLEATION OF THE ORBITAL CONTENTS THE eyes one procures from a butcher or a slaughter house will always have the extrinsic tissues so badly cut and torn that identification of the various parts and their relations is impossible. Therefore, it is best to supply one's self with the head of an animal, such as a sheep or a calf, and dissect an eye with all its extrinsic tissues intact. For this dissec- tion, a hammer and a, chisel are necessary in addition to the tools needed for doing the previous dissections. Using the left orbit, begin the dissection by making an incision directly over the supra- orbital ridge, extending from over the inner to the outer canthus. At the middle of that line, make an incision, and cut at right angles up- ward to the top of the head. Next make a cut below the eye, extending from the outer to the inner canthus. (Fig. 47.) Loosen the skin 97 o bjo £ 98 TECHNIQUE OF EYE DISSECTIONS Fig. 48 — Part of calf 's head, showing the first cut to be made in the bones of the orbit. (Page 102.) from the bone with the scalpel, and lay bare the skull immediately over the orbit. Fold the flaps of the skin back and fasten them down to the skull with pins or tacks so they will not interfere with the work. Using the hammer and the chisel, cut 99 TECHNIQUE OF EYE DISSECTIONS through the roof of the orbit at the middle of the supra-orbital ridge, and continue upward for about two and one-half inches. Do not strike hard blows, or the chisel may be driven Fig. 49 — Showing all the cuts to be made through the bones of the orbit. (Page 102.) through the underlying tissues. Listen for the peculiar sound that is heard when the bone has been completely penetrated; then re- move the chisel. Continue until the full dis- tance of two and one-half inches of bone has 100 TECHNIQUE OF EYE DISSECTIONS Fig. 50 — Showing how to pry the cut bone loose. (Page 102.) 101 TECHNIQUE OF EYE DISSECTIONS been separated. (Fig. 48.) Now, begin at the upper end, and cut through the bone downward to the right for about two inches toward the Fig. 51 — ' ' In removing orbital contents dissect close to the bone." outer canthus. A similar line should be cut on the right of the centre line toward the inner canthus. This will mark out two irregular, triangular-shaped pieces of bone. (Fig. 49.) Remove the piece on the right-hand side by prying it off. (Fig. 50.) The left-hand piece should be pried loose and then carefully cut away with the scalpel, so that the pulley through 102 TECHNIQUE OF EYE DISSECTIONS which the superior oblique muscle runs its tendon, will not be injured. In removing the orbital contents, dissect close to the bone (Fig. 51), so that the periosteum will also be re- moved, and form a sort of sac or capsule in Fig. 52 — Showing excavated orbit. (Page 105.) which will be contained the eye with all its extrinsic tissues. If difficulty is experienced in getting at the posterior parts of the orbit, it will be best to cut away as much more of the obstructing bone as is necessary. In this way the "capsule" containing the eye, its six 103 TECHNIQUE OF EYE DISSECTIONS Fig. 53 — Anterior view of the enucleated eye. Fig. 54 — Showing the enucleated eye, its muscles, and its accessories, all in situ. 104 TECHNIQUE OF EYE DISSECTIONS muscles, the lacrimal gland, and both eyelids, all in situ, will be removed. (Fig. 54.) As the orbital entrance of the optic nerve is neared, care must be exercised not to cut into this "capsule," or sever any of the muscles. (Fig. 52 shows the excavated orbit. Fig. 53 shows an anterior view of the enucleated eye. Fig. 54 is a side view of the enucleated eye.) 105 OPHTHALMOSCOPIC EXAMINATION BY practising on an enucleated eye, one may gain considerable ability in the use of the ophthalmoscope, and also learn to recognize the blood-vessels and other important parts of the retina. To'do this, the eye to be examined must be very fresh, for only in this condition will the cornea and lens be sufficiently clear to permit rays of light to enter the inside of the eye. However, since the pupil is oblong in shape, and often only a narrow slit — but several millimetres in diameter — the field presented for observation is a rather limited one. To 5- increase the pupillary aperture, take a pin, and force the point through the cornea about three or four millimetres from the corneo- scleral junction, and at right angles to the direction of the parallel edges of the pupil. After the pin has been pushed through until it has reached to within a short distance (one 106 TECHNIQUE OF EYE DISSECTIONS millimetre) of the edge of the iris, carefully pick up the iris by raising the pin into a position perpendicular to the cornea, and force Fig. 55 — Showing one pin before the iris has been picked up and pulled back, and three pins after the iris has been picked up and pulled back. the pin further down into the eye. The pupil will have been enlarged on one side. Do the same thing on the opposite side, and at each extremity of the pupil. (Fig. 55.) 107 TECHNIQUE OF EYE DISSECTIONS Fig. 56 — Showing method of gathering up the extrinsic tissues in order to get rid of the pucker in the cornea. The pupil will now have been made square, and so.. large that no difficulty will be experi- enced in reflecting either light into the eye, or 108 TECHNIQUE OF EYE DISSECTIONS in examining the inside of the eye. Care must be taken not to lacerate the anterior surface of the lens when the iris is drawn back by the pins. Putting the pins into the cornea, and using them as levers with the point of entrance in the cornea as a fulcrum, will pucker the cornea considerably, and a good clear fundus cannot be obtained. This is easily overcome. Simply gather up all the tissues surrounding the eye, force them backward, and hold them firmly with the fingers of the left hand. (Fig. 56.) The right hand is then free to handle the skia- scope or ophthalmoscope, so that the interior of the eye may be thoroughly examined. Another way to prepare an eye for ophthal- moscopic examination is as follows: Go to a slaughter house and procure a beef eye from an animal that has been killed but a few min- utes previously. Placing the eye immediately into an 8 per cent, solution of cocaine and leaving it there for about an hour will dilate the pupil to such an extent that work with the ophthalmoscope will be made very easy. This, 109 TECHNIQUE OF EYE DISSECTIONS as indicated, can be done only with an eye that is very fresh. Still another way to see the interior is to cut out a piece of the sclerotic about the size of a twenty-five-cent piece; then pinch up and tear Fig. 57 — Showing window cut in sclerotic, choroid, and retina. out the choroid and the retina under the open- ing made in the sclerotic. (Fig. 57.) Hold the eye, the cornea forward, close to a bright light, and the image of the light will be seen upon the retina, The closer the light is to the eye, the greater the illumination will be in the 110 TECHNIQUE OF EYE DISSECTIONS interior of the eye. If the opening or "win- dow" is close enough to the optic nerve, the optic papilla can be seen easily. And, if care has been taken to have the opening made mid- way between the two branches of the retinal artery, the entire course may be followed. The direction of the retinal artery can be deter- mined by ophthalmoscopic examination. Ill THE LACKIMAL DUCTS To find the lacrimal ducts, cut across the cuter and inner canthi of the enucleated eye, pushing the eye forward and the lids back- ward. That will expose the conjunctiva of Fig. 58 — Showing how pins may be inserted in lacrimal ducts. 112 TECHNIQUE OF EYE DISSECTIONS both eyelids and eye, and also show the con- junctiva! fornices. On the upper surface of the palpebral conjunctiva, and near the outer can thus, will be seen, upon close inspec- tion, a number of minute openings, usually eight. These are the openings of the lacrimal ducts. Pins or straw that have been lubricated with vaseline, may be inserted and pushed into these openings for a considerable distance, and the course of the ducts then can be traced easily. (Fig. 58.) 113 THE LACRIMAL GLAND • THE lacrimal gland is easily distinguished by its pink appearance. There are two parts, inferior and superior. The gland lies directly over the eye and near the outer angle of the orbit. In the enucleated eye, it will be found to lie near the outer canthus and over the eye. The gland may be easily dissected out of its position and then examined more closely. A hand lens will show the racemose construc- tion of the gland. If the gland is cut in two, the racemose construction may be seen even better. 114 THE CAPSULE OF TENON To dissect the capsule of Tenon, it is neces- sary to carefully remove the superficial fat Fig. 59 — Enlarged to show part of the Capsule of Tenon blown up. (Page 116.) and connective tissue. In text-books and illus- trations, the capsule is usually shown as a definite sac-like membrane of considerable thickness, with all its parts well defined. The 115 TECHNIQUE OF EYE DISSECTIONS dissector will soon find that the capsule is not discerned so easily. It will be found to be the thin, semi-transparent, fibrous membrane that surrounds each muscle, as well as the "pos- terior two-thirds of the eye," and is continu- ous anteriorly with the ocular conjunctiva. Portions may be pinched up and inflated through an inserted blow-pipe. This will help to merely demonstrate its location and parts. (Fig. 59.) 116 THE SUPERIOR OBLIQUE MUSCLE AND ITS PULLEY AFTEE the lacrimal gland has been dissected away, a beginning will have been made for cut- ting away the fat and the connective tissue. The first thing to do then is to locate the su- perior oblique muscle. Try to keep track of which part of the eye is the inner side. Hav- ing located the inner side, feel along the top for a little hard eminence. That is the pulley. Begin to dissect around the pulley, not through it, and then follow the muscle along to its origin; do not separate the muscle from its origin. When the superior oblique is com- pletely freed, the action of the muscle may be readily demonstrated by holding the "ring" or tendinous pulley with the fingers of one hand, while the muscle is pulled backward and forward with the other. 117 THE OTHER EXTRINSIC MUSCLES WITH the dissection of Tenon's capsule and the superior oblique muscle, the work of iso- lating the other extrinsic muscles will have begun. This work needs no directions except Pig. 60 — Showing the tendinous pulley of the superior oblique muscle and the extrinsic muscles. 118 TECHNIQUE OF EYE DISSECTIONS a warning to be careful not to injure the pul- ley of the superior oblique, and to be careful not to cut away the inferior oblique. The in- ferior oblique will be found to be near the " pulley. " If the dissection is not carried too close to the origin of the recti muscles, all the muscles may be kept in place. If the eye has not been previously subjected to the hardening influence of formaldehyde, it may be put into a 5 per cent, solution, and at the end of ten or twelve hours the muscles will have become rigid. They can then be bet- ter studied, and may be kept indefinitely. (Fig. 60.) 119 THE THREE TUNICS OF THE EYE, THE HYALOID AND ITS ATTACHMENTS THIS dissection is a rather difficult one to make, and requires patience. Prepare an eye by placing it in a 5 per Fig. 61— Cutting through the iris. cent, solution of formaldehyde for about ten days to two weeks. Eemove all the outside tissues. Cut away the cornea, as in the dis- section for the choroid or the retina. Loosen, as far back as possible, the sclerotic from the choroid. Pemove the sclerotic for about 10 mm. back of the equator of the eye. With the tweezers pick up the pupillary edge of the iris. Using the small pointed scissors, cut through 120 TECHNIQUE OF EYE DISSECTIONS the iris. (Fig. 61.) Lift either one of the cut edges of the iris, and, with the sharp edge of the scalpel, gently scrape the processus zonu- loe free from the ciliary processes, cutting Fig. 62 — Scraping the ciliary processes free. Showing, also, the choroid cut around the ciliary ring. through the ciliary ring as the ciliary pro- cesses are detached from the hyaloid (pro- cessus zonuloe}. (Fig. 62.) Great care must be taken not to thrust the point of the scissors into the hyaloid, suspen- sory ligament, or vitreous, else the lens may become detached. 121 TECHNIQUE OF EYE DISSECTIONS After the iris with the processes has been removed, pinch up with the tweezers a fold in the choroid. Make an incision with the fine- pointed scissors, and begin removing the cho- Fig. 63 — Cutting away the choroid. roid to within about 5 mm. of the cut end of the sclerotic, (Fig. 63.) Care must be taken not to penetrate the underlying retina while mak- ^g this part of the dissection. .After part of the choroid has been removed, specimen will show the three coats of the c 3 in layer-like arrangement, the hyaloid and 122 TECHNIQUE OF EYE DISSECTIONS lens. The lens may now be cut away, if the specimen is preferred without it, Eemoving the lens before this time is unwise, because it acts as a protection to the other tissues while the specimen is being handled during the dis- section. This specimen will show to the best advan- tage if it is suspended in a jar containing a 5 per cent, solution of formaldehyde. Figure 64 shows the specimen. Fig. 64 — A. Optic nerve. B. Sclerotic. C. Choroid. D. Eetina. E. Hyaloid. F. Lens. 123 INDEX Accessories, ocular, 95 Alcohol as a preservative, 34 of running Capsule of Tenon, 115 of Tenon and conjunctiva, 116 Cedar oil, 60 >0, 51, 86, 90 half of eye, 49 half, removing vitreous from, 49 surface of lens, 55 Aperture, increasing pupillary, 106, 107, 109 Aqueous humor, 51 Arteria centralis retinae, 43, 49 Arteries, ciliary, 72 course of retinal, 111 Artery of retina, central, 43, 49 hyaloid, 43 B Beef eyes, 26, 27 Beginning of dissection of orbital contents, 97 Benzine, 59 Blood-vessels of retina, 106 Blowing through blowpipe, fold- ing retina by, 81, 82 Blowpipe, folding retina by blow- ing through, 81, 82 glass, 35 using it to force out vitreous, 78-81 Body, hyaloid, 41 Boiling crystalline lens, 55, 56 Books, text, 23, 25, 46, 52 Canal, hyaloid, 43 of Petit, 35-37 Canaliculi, puncta, papilla, and nasal duct, locating, 92-95 Capsule of lens, 33, 50, 54 of lens, removing, 59 .0, 51, 86, 90 r, 50, 51, 86, 90 Chemicals, 22, 23 Chisel and hammer, use of, 99-101 Choroid, 62 and sclerotic, cutting them away for isolating retina, 83 emptying, 69, 70 for dissecting three tunics, re- moving, 122 from sclerotic, for dissection of three tunics and hyaloid, loosening, 120 iridescence of, 45 loosening from corneo-scleral junction, 64, 65 loosening sclerotic from, 64, 66, 67, 68 or retina, removing cornea for isolating, 62, 63, 64 picking up retina and, 30, 31 preparing eye for isolating, 62 preserving isolated, 72 removing, 46 removing lens from, 69, 70, 71 scraping sclerotic from, 68 separating sclerotic from, 27, 29 Cilia and other superficial acces- sories, 95 Ciliaris, corona, 49, 51 orbicularis, 49, 51 retinae, pars, 49 Ciliary arteries, 72 nerves, 72 processes, 27, 33, 49 processes free from processus zonuloe, scraping, 121 ring, 51 ring, cutting ciliary, 121 125 INDEX Ciliary, clarifying lens, 58, 59 Coats, preparing eye for dissec- tion to show, in situ, the three, 120 Cocaine, 109 Color of processes, 50 Concentric layers of lens, 56, 57 Conjunctiva and Capsule of Tenon 116 Conjunctival fornices, 113 Cornea, epithelium of, 52 removing it for isolating cho- roid or retina, 62, 63, 64 Construction of lacrimal gland, racemose, 114 Contents, beginning of dissection of orbital, 97-101 dissecting orbital, 97-105 emptying eyeball of, 32, 33 enucleating orbital, 102-104 material for enucleation of or- bital, 97 preserving of hyaloid, 32, 33 34, 36 Cornea, 52 and sclerotic, 52 layers of, 52 smoothing it for ophthalmo- scopic examination, 109 Corneo-scleral junction, loosen- ing choroid from, 64, 65 Corona ciliaris, 49, 51 Cortex of lens, 54, 59 Course of retinal arteries, 111 Cross section of optic nerve, 48 Crystalline lens, 33, 49, 53 lens boiling, 55 Cutting away sclerotic and cho roid for isolating retina, 83 ciliary ring, 121 cross section of optic nerve, 48 eye for sagittal section, 87-89 eye in half, 38, 39 iris for dissection of three tu- nics, 120 optic nerve longitudinally, 47, 48 Dehydrating lens, 58, 59 Demonstration of hyaloid, etc., 34 Disc, optic, 43 Dishes, Stender, 21 Dissected hyaloid, 33 Dissecting lacrimal gland, 114 nasal duct, papilla and puncta, 92 orbital contents, 97-105 of hyaloid membrane, 25, 33 of hyaloid, method of prepar- ing for, 26, 27 of orbital contents, beginning of, 97-101 three tunics, removing choroid, for, 122 Dissection, preparing eye for in- terior, 38 preparing eye to show the three tunics in situ, 120 of three tunics and hyaloid, loosening choroid from scler- otic for, 120 of three tunics, cutting iris, for, 120 Duct, material for dissecting pa- pilla, puncta, and nasal, 92 papilla, puncta lacrimalia, and nasal, 92 Ducts, meibomian gland and, 96 lacrimal, 112, 113 Emptying choroid, 69, 70 eyeball of contents, 32, 33 Entrance of optic nerve, 43 Enucleated eye, 104 Enucleating orbital contents, 102- 104 Enucleation of orbital contents, 97-105 of orbital contents, material for, 97 Epithelium of cornea, 52 Equipment, 17-24 Examination, ophthalmoscopic, 106 preparing eye for ophthalmo- scopic, 106-110 smoothing out cornea for oph- thalmoscopic, 109 Excavated posterior half, 46, 47 sagittal, 90 126 INDEX Extrinsic muscles, other, 118 muscles, preserving, 119 Eye, anterior half of the, 49 contents, emptying, 32, 33 cutting it for sagittal section, 87-89 for dissection of hyaloid, etc., preparing, 26, 27 in half, cutting, 38, 39 interior of, 38 posterior half of the, 40 Half, excavated posterior, 46 posterior, 40 posterior, excavated, 46 preparing eye for dissecting in- terior, 38 removing vitreous from ante- rior, 49 removing vitreous from pos- terior, 41 Hammer and chisel, use of, 99- 101 preparing for dissecting inter- Humor, aqueous, 51 ior, 38 vitreous, 33 preparing it for dissection, to Hyaloid and attachments, demon- show the three tunics, in situ, 120 preparing for isolating cho- roid, 62 preparing for isolating retina, 74, 75 preparing for ophthalmoscopic examination of, 106-110 preparing for sagittal section of, 86 sagittal section of, 86 seeing interior of, 110 vertical section of, 86 cutting window in, 110 Eyelids, 95, 105 Eyes, sheep and beef, 26, 27 Fibres of lens, 56, 57 network of vitreous, 41, 42 Fluid, perichoroidal, 40, 46 Folding retina by blowing air through blowpipe, 81, 82 Forcing out vitreous, using blow- pipe in, 78-81 Fornices, conjunctival, 113 G Gland, dissecting lacrimal, 114 lacrimal, 114 racemose construction Glands and ducts, meibomian, 96 Glass blowpipe, 35 Glassware, 21 H Half, anterior, 49 cutting eye in, 38, 39 stration of, 34 artery, 43 body, 41 canal, 43 dissected, 33 membrane, dissection of, 25-33 membrane with contents and attachments intact, removal of, 25 preserving contents of, 32, 33, 34, 36 preserving three tunics and, 123 Image, retinal, 110 Increasing pupillary aperture, 106, 107, 109 Inferior oblique muscle, 119 Instruments, 21 Interior of the eye, 38 of the eye, seeing, 110 Interior section, preparing the eye for dissecting, 38 Iridescent choroid, 40, 43 Iris, 49, 51 and lens, removing, < 6, 77 and processes, removing, 121 for dissection of three tunics, cutting, 120 relation between processes and, 51, 52 Isolated choroid, preserving, 72 Isolating choroid or retina, re- moving cornea for, *62-64 choroid, preparing eye for, 62 Isolated retina, preserving,, 84, 85 127 INDEX Isolating retina, cutting sclerotic Loosening choroid from and choroid away for, 83 retina, preparing eye for, 74, 75 Junction, loosening choro:d from corneo-scleral, 64, 65 K Knitting-needles, use of, 92-95 L Lacrimal ducts, 112, 113 gland, 114 gland, dissecting, 114 scleral junction, 64, 65 choroid from sclerotic, 64, 66- 68 choroid from sclerotic, for dis- section of the three tunit-s and hyaloid, 120 Lucidum, tapetum, 45 M Material, 19, 20, 21 for dissecting nasal duct, pa- pilla, and puncta, 92 for enucleation of orbital con- tents, 97 Meibomian glands and ducts, 96 gland, racemose construction of Membrane with contents and at- tachments intact, removal of, 25 Method of preparing eye for dis- section of hyaloid, 26, 27 of running through the alco- hols, 58, 59 Muscle, superior oblique and its pulley, 117 Muscles, other extrinsic, 118 preserving extrinsic, 119 114 Lacrimalia, nasal duct, papilla, and puncta 92 Laminated structure of lens, 55, 56 Layers, concentric lens, 56, 57 of cornea, 52 separating outer lens, 54 Lens and iris, removing, 75, 77 anterior surface of, 55 boiling of, 55, 56 capsule, 33, 50, 54 clarifying, 58, 59 concentric layers of, 56, 57 cortex of, 54, 59 crystalline, 33, 49, 53 dehydrating, 58, 59 fibres, 56, 57 N Nasal duct, canal:culi, puncta, and papilla, locating, 92-95 canaliculi, puncta, and papilla, 92 canaliculi, puncta, and papilla, material for dissecting, 92 laminated structure of, 55, 56 Needles and pins, use of, 96, 106, nucleus of, 55, 59 107, 108, 109, 112, 113 use of knitting, 92-95 Nerve, cross section of optic, 48 entrance of optic, 43 optic, 47 optic, cutting it longitudinally, 47, 48 separating outer layers of, 54 Nerves, ciliary, 72 staining, 57 Network of fibres in vitreous, 41, Ligament, suspensory, 33, 37 42 Lines, tri-radiate, 54-56 Nucleus of lens, 55, 59 Locating papilla, puncta, canali- culi, and nasal duct, 92-95 Longitudinally, cutting optic Oblique, inferior, 119 nerve, 47, 48 pulley of superior, 117 128 posterior surface of, 55 preparing the, 53 preserving the, 57, 58 removing capsule of, 59 removing it from choroid, 69-71 removing the, 51, 53 INDEX Ocular accessories, 95 Pins and needles, use of, 96, 106- conjunctiva and Capsule of Ten- 109, 112, 113 on, 116 Pipette, 35 conjunctiva and other super- Posterior chamber, 50, 51, 86, 90 ficial accessories, 95 half excavated, 47 Oil, cedar, 60 Ophthalmoscope, 109 Ophthalmoscopic examination, 106 examination, preparing eye for 106-110 examination, smoothing out cor- nea for, 109 Optic disc, 43 nerve, 47 nerve, cross section of, 48 nerve, cutting it longitudinally, 47, 48 nerve, entrance of, 43 papilla, 111 Ora serrata, 49 Orbicularis ciliaris, 49, 51 half of the eye, 40 half, removing vitreous from, 41 surface of the lens, 55 Preparing eye for dissecting in- terior, 38 eye for dissecting hyaloid, 26, 27 eye for dissection to show the three tunics, in situ, 120 eye for isolating choroid, 62 eye for isolating retina, 74, 75 eye for ophthalmoscopic exami- nation, 106-110 eye for sagittal section, 86 the lens, 53 Orbital contents, beginning dis- Preservative, alcohol as a, 34 section of, 97-101 Preserving extrinsic muscles, 119 contents, dissecting, 97-105 hyaloid, contents and attach- contents, enucleating, 102-104 contents, enucleation of, 97 contents, material for enuclea- tion of, 97 ments, etc., 32-34, 36 isolated choroid, 72 isolated retina, 84, 85 lens, 57, 58 sagittal sections, 89 three tunics and hyalo'd, 123 Palpebra? and other superficial ac- Processes, ciliary, 27, 33, 49 cessories, 95 and iris> removing, 121 Palpebral conjunctiva and other color of> 50 superficial accessories, 95 Papilla, nasal duct, and puncta lacrimalia, 92 pigment cells of, 49, 50 relation between iris and, 51 52 zonular, 27, 34 nasal duct, and puncta lacri- Processus zonuloe, 34 malia, material for dissect- zonuloe free from ciliary pro- cesses, scraping, 121 Pulley of superior oblique mus- cle, 117 Puncta lacrimalia, nasal duct, and papilla, 92 lacrimalia,. 'papilla, canaliculi, and nasal duct, locating, 92, 95 lacrimalia, papilla, canaliculi, ing, 92 optic, 111 puncta, canaliculi, and nasal, duct, locating, 92-95 Pars ciliaris retinse, 49 Perichoroidal fluid, 40-46 Petit's canal, 35-37 Picking up choroid and retina, 30, 31 Pigment cells of processes, 49, 5:j of sclerotic, 46 removal of, 34 Pinching up sclerotic, 27, 28 and nasal duct, material for dissecting, 92 Pupillary aperture increasing, 106, 107, 109 129 INDEX R Racemose construction of lacrimal gland, 114 References, 23, 25, 46, 52 Relation between iris and pro- cesses, 51, 52 Removal of hyaloid membrane with contents and attach- ments intact, 25 of pigment from processus zonuloe, 34 Removing capsule of lens, 59 choroid, 46 cornea for isolating choroid or retina, 62-64 iris and lens, 75, 77 choroid for dissecting three tu- nics, 122 iris and processes, 121 lens from choroid, 69-71 lens from anterior half and other parts, 51, 53, 54 sclerotic to show the three tunics, 120 the retina from posterior half, 44 vitreous from anterior half, 49 vitreous from choroid, 70-72 vitreous from posterior half, 41 Retina, 40-74 blood-vessels of, 106 central artery of, 43, 49 cutting away sclerotic and cho- roid for isolating, 83 folding it by blowing air through blowpipe, 81, 82 Running through the alcohols, 58, 59 S Sagittal section, cutting eye for, 87-89 section, excavated, 90 section of the eye, 86 section, preparing eye for, 86 sections, preserving, 89 Sclerotic and choroid, cutting them away for isolating ret- ina, 83 and cornea, 52 from choroid, for d'ssection of three tunics and hyaloid, loosening, 120 loosening choroid from, 64, 66- 68 pigment of, 46 pinching up, 27, 28 scraping choroid from, 68 separating choroid from, 27, 29 to show the three tunics, remov- ing, 120 Scraping choroid from sclerotic, 68 processus zonulce free from cil- iary processes, 121 Section of optic nerve, cross, 48 cutting eye for sagittal, 87-89 preparing eye for sagittal, 86 sagittal, 86 vertical, 86 or choroid, removing cornea for Sections, preparing eye for dis- isolating, 62-64 secting interior, 38 picking up choroid and, 30, 31 preserving sagittal, 89 preparing eye for isolating, 74, Seeing interior of eye, 110 75 preserving isolated, 84, 85 removing, 44 straightening, 42, 43 Retinae, pars ciliaris, 49 Retinal artery, course of, 111 image, 110 vessels, 40, 49 Ring, ciliary, 51 cutting c'liary, 121 of superior oblique muscle ten- Staining lens, 57 dinous, 117 Stender dishes, 21 130 Separating choroid from sclerot'c, 27, 29, 64-68 outer layers of the lens, 54 Serrata, ora, 49 Sheep eyes, 26, 27 Skiascope, 109 Smoothing cornea for ophthalmo- scopic examination, 109 Superior oblique muscle and its pulley, 117 INDEX Straightening retina, 42, 43 Structure of lens, laminated, 55, 56 Superior oblique muscle, pulley of, 117 Surface of anterior of lens, 55 of posterior of lens, 55 Suspensory ligament, 55 Tapetum lucidum, 45 Tendinous ring of the superior oblique muscle, 117 Tenon and ocular conjunctiva, Capsule of, 116 Tenon's Capsule, 115 Text-books, 23, 25, 46, 52 Three tunics, removing choroid, for dissecting, 122 Tools, 21 Tri-radiate lines, 54-56 Tunics, in situ, preparing eye for dissection to show the three, 120 preserving hyaloid and three, 123 removing the sclerotic, to show the three, 120 U Use of hammer and chisel, 99-101 of knitting-needles, 92-95 Using blowpipe in forcing out vit- reotis, 78-81 Vena vorticosa, 72 Vertical section of the eye, 86 Vessels of retina, blood-, 40, 49, 106 Vitreous, 33 network of fibres in, 41, 42 removing from anterior half, 49 removing from posterior half, 41 using blowpipe to force out, 78- 81 Vorticosa, vena, 72 W Window, in eye, cutting, 110 Xylol, 59 Zone of Zinn, 36, 37 Zonular processes, 27, 34 Zonulii Zinii, 36, 37 Zonuloe processus, 34 131 14 DAY USE RETURN TO DESK FROM WHICH BORROWED OPTOMETRY LIBRARY This book is due on the last date stamped below, or on the date to which renewed. Renewed books are subject to immediate recall. vJUiaiTffT - MA**feW85 JJOT^ii^§87 rj yj f^ I v ^ vV / DEC 0 9 1999 B •i , LD21— 32m— 1,'75 (S3845L)4970 General Library University of California Berkeley GIL U.C. BERKELEY LIBRARIES c . \ CDDSbSS331 HI