Paul Henkind

EXPERIMENTAL OCCLUSION OF RETINAL ARTERIOLES (USING GRADED GLASS BALLOTINI)

DISEASE of the retinal vessels usually involves in varying degree the whole retinal vascular system, so that in considering the pathogenesis of any particular lesion it is often difficult to decide whether it is primarily related to the arterioles, capillaries, or venules. From the experimental point of view it would be of value if the sequelae of uncomplicated lesions in each part of the vascular tree could be separately studied. With this object in mind we have sought, as an initial step, a suitable material with which to occlude in vivo the retinal arterioles. The artificial emboli must, of course, be the appropriate size, and should be inert, easily identifiable, and simple to prepare, to inject, and to store. We have found that small glass balls or ballotini are eminently satisfactory for this purpose and, to make the method available to others pursuing similar lines of work, we report in this preliminary communication a description of our technique together with a brief survey of some of our findings.

I. Ophthalmoscopic and circulatory changes in focal retinal ischaemia.

*A*naesthea 286 . ........... * * aFactors influencing capillary collateral Anaesthesia .. .. .. .. .. 286 flow .. Premedication . . .. .. 286 Size of embolized vessel Induction .. .. .. .. .. 286 Site of the lesion Intubation ......... .. .. .. .. 286 Early changes in collateral flow (0-6 Maintenance of anaesthesia .. .. 287 hours) .. .. Operative technique .. .. .. 287 Late changes in collateral flow (24 hours Control of the eye .. .. .. 288 to 6 weeks) .. Technical difficulties .. .. .. 288 Position of larger collaterals Injection of emboli .. 289 Vascular leakage.. Photographic methods .. 290 Injection studies .. Cine photography 290 Correlation of clinical and angiographic Cine photography .. *. *. findings in embolized retina.. Analysis of photographic material .. .. 291 Histopathological study .. .. .. 291 Discussion .. .. Indian ink injections .. .. .. 291 Circulatory dynamics Digestion procedure .. .. .. 292 Vascular micro-anatomy Routine histology .. .. .. .. 292 Pressure-flow relations in the normal eye Immediate consequences of arteriolar obstruction .. .. Results .. .. .. .. .. .. 293 Growth of larger collateral channels Visible changes in the retina following Cotton-wool spots .. embolization .. .. .2.. 293 Immediate consequences of embolization 296 Acknowledgements .. Early changes (0-6 hours) .. .. 296 References Late changes (24 hours to 6 weeks) .. 297 Angiographic studies .. .. .. 298 Illustrations .. .. PAGE

The retinal vascular system of the domestic cat

The retinal vascular system of the domestic cat was studied clinically, and by a variety of histological techniques. Fundus photographs and drawings were utilized to point out features of the retinal vasculature during life, and routine histology, electron microscopy, ink injections and digest preparations were used for in vitro study. While the present observations usually confirmed previous work on the retinal vascular system of the cat, a number of points of difference were noted. A comparison of the retinal capillaries with those of the choriocapillaris is provided. An arcuate arrangement of retinal arterioles was noted in cat, monkey and man, and is similar to that noted in other vascular beds. The retinal circulation of the cat was found to have many points of similarity with that of man.

Bilateral internal ophthalmoplegia in a patient with sarcoidosis.

Ocular signs are common in systemic sarcoidosis. Upwards of 50 per cent. of affected patients develop a granulomatous anterior uveitis, and fundus lesions are frequently observed. Ocular findings due to central nervous system involvement are less frequent, but can be the initial complaint. The subject of central nervous system involvement in sarcoidosis has been reviewed by Colover (I948) and Walsh and Hoyt (i 969a). In this paper, we report a patient whose initial ocular manifestation of sarcoidosis was an internal ophthalmoplegia. Her systemic illness went undiagnosed for many months until she developed a severe bilateral granulomatous uveitis and secondary glaucoma. The literature dealing with internal ophthalmoplegia in sarcoidosis is reviewed.

MIGRATION OF LIMBAL MELANOCYTES INTO THE CORNEAL EPITHELIUM OF GUINEA-PIGS.

The corneal epithelium of the guinea-pig normally contains few if any pigmented melanocytes. Following the injection of alloxan into the anterior chamber, or topically applied colchicine drops, the guinea-pig develops corneal vascularization, and this is accompanied by melanocyte migration from the pigmented limbus into the basal layers of the corneal epithelium. Though the melanocytes can be demonstrated in routine histological preparations, flat preparations of the epithelium, with or without underlying stroma, are more instructive. Corneal epithelial melanocyte migration is distinet from the process of limbal ȁslidingȁ. In the former, melanocytes actively migrate into the basal layers of the epithelium, whereas in the latter, pigment-containing Malpighian cells from the limbus cover previously denuded corneal epithelium.

Schwann Cell Proliferations Mimicking Medullated Retinal Nerve Fibers

Ophthalmoscopically visible white patches in the optic nerve head and adjacent retina in a rhesus monkey histologically represented peripheral rather than central nervous myelin. This case of Schwann cell proliferations appearing as medullated retinal nerve fibers raises questions concerning the relationship of this phenomenon to developmental and acquired lesions of the optic nerve head in man.

CIRCULATION IN THE IRIS AND CILIARY PROCESSES: POSSIBLE RECIPROCAL RELATIONSHIP

A RECENT observation in experimental animals suggests that there may be a reciprocal relationship between the arterial blood flow in the ciliary processes and the iris. While this process has not been conclusively proven, it appears of sufficient interest to warrant mention. In mammals, the ciliary processes and iris derive their arterial supply solely from the major arterial circle of the iris t. This circle is formed by anastomosis of the terminal branches of the medial and lateral long posterior ciliary arteries and anterior ciliary arteries. Besides the arteries subserving the ciliary processes and the iris, the major circle also provides some of the recurrent branches to the choroid though these tend to be small. There is little or no evidence to suggest a collateral arterial blood supply for the iris and ciliary processes by any other route. Thus the two tissues comprising a portion of the anterior uvea share a common vascular supply. It is difficult at present to ascertain how much blood either tissue takes from the major circle. Grossly (in rabbits, rats, and in guinea-pigs), it appears that ciliary processes have slightly wider arterial channels than the iris. However, the arterioles of the ciliary processes tend to bend obliquely backwards, whereas the vessels of the iris generally come straight forward off the circle, possibly favouring flow towards the iris. Not infrequently, a branch from the major circle supplies both iris and ciliary processes. Variations in size of the pupil with consequent change in the path of the iridic vessels would appear to modify blood flow to this tissue and perhaps secondarily affect flow to the ciliary processes. The present report stems from the following observations: In an attempt to outline the intra-ocular vascular tree of rats, Indian ink was injected into the still-beating heart of the terminally anaesthetized animal. In several instances the intra-ocular vessels, with the exception of those in the ciliary processes, filled completely, creating a rather striking picture (Fig. 1, opposite). In other instances, only a portion of the ciliary processes was filled with Indian ink, whereas blood could be seen in the uninjected portion of the process. It was noted, however, that when atropine had been instilled into the eye before injection the ciliary processes filled adequately with ink, and that the iridic vessels occasionally appeared less well filled (Fig. 2, opposite). As a consequence of the above observations, the following experiment was performed: Pilocarpine drops 4 per cent. were instilled into the right conjunctival sac and atropine

Adenocarcinoma of the Ciliary Body A Report of 2 Cases in Dogs

Two cases of adenocarcinoma of the ciliary body in the dog are described. Invasion of ocular tissues and, in 1 case, extraocular tissue occurred, however distant metastasis did not. These characteristics are similar to those of such tumors in man.

Some observations about retinal vascular-neuronal interrelationships.

The relationship between the intraretinal vessels of the human fundus and the surrounding neuronal tissue is discussed with regard to various disease states. Present evidence suggests that primary retinal neuronal death does not lead to secondary retinal capillary death. Primary retinal capillary non-perfusion generally leads to concomitant retinal neuronal degeneration, but if the occlusion takes place over a long period of time the surrounding neural retina may survive. It is suggested that many retinal degenerative changes, including retinal detachment, are due to primary retinal vascular alterations.

George Nelms Wise, M.D. 1915-1974

up care. The guest speakers will be the following: Mr. Peter Choyce and Drs. Robert Drews, Miles Galin, and Nor¬ man Jaffe. Members of the faculty will also participate. Registration fee will be