A Study of Surgical Approaches to Retinal Vascular Occlusions

SURGICAL TECHNIQUE A Study of Surgical Approaches to Retinal Vascular Occlusions

William M. Tang, MD; Dennis P. Han, MD

Objective: To develop a surgical approach to retinal vas- nulations of central retinal arteries were successful in 0 cular occlusive diseases. of 2 procedures, and cannulations of central retinal veins were successful in 2 of 4 procedures. Arteriovenous Methods: Surgical manipulations were performed on the sheathotomies were successful in 4 of 7 procedures. In retinal vasculature to explore the feasibility of retinal vas- the in vivo model, surgical penetration of retinal blood cular surgery. In a human cadaver eye model (25 proce- vessels was accomplished in 5 of 6 eyes. Immediately post- dures, 21 eyes), we performed (1) cannulations of retinal operatively, thrombus formation with obstruction of the blood vessels with a flexible stylet and (2) arteriovenous retinal vasculature was observed. At 2 weeks postopera- sheathotomies. Histological findings were correlated with tively, the retinal vasculature was completely patent. surgical outcomes. In an in vivo model (6 eyes, 5 animals), we examined the technical feasibility and anatomical out- Conclusions: Multiple surgical techniques aimed at as- come of surgical penetration of retinal blood vessels. sisting recanalization of occluded retinal vasculature have been evaluated. Retinal vascular surgery has become more Results: Cannulations of branch retinal arterioles were feasible and deserves further investigation. successful in 7 of 9 procedures, cannulations of branch retinal venules were successful in 1 of 3 procedures, can- Arch Ophthalmol. 2000;118:138-143

ETINAL ARTERY and vein oc- endovascular therapy can lead to reversal clusions are among the of retinal vascular occlusions. most common causes of se- The technique of endovascular therapy vere vision loss. In the Blue involves 2 important steps: (1) mechani- Mountains Eye Study, the cal access of a catheter into the vascular lu- prevalence of retinal vein occlusion was men and (2) navigation of the catheter to R 10 found to be 1.6% in adults aged 49 years the desired site of action. We applied this or older.1 Standard treatment is generally technical concept to the retinal vascula- ineffective in restoring blood flow.2,3 ture. In a human cadaver eye model, we de- We are attempting to develop new veloped surgical techniques to (1) gain ac- treatments that might be effective in cess into the retinal vasculature and (2) restoring blood flow in retinal vascular cannulate retinal blood vessels with a flex- occlusions. We believe that significant ible stylet. In an in vivo model, we exam- therapeutic advances must be directed to ined surgical techniques for gaining ac- the obstructive process in the vascular cess into the retinal vasculature. The lumen.4-6 The unique opportunity to technical feasibility and anatomical out- visualize and access the retinal vascula- come of these procedures were evaluated. ture during vitreous surgery led us to Another portion of our study ad- From the Departments of consider developing an intraocular, dresses the recent interest in arteriove- Ophthalmology, Boston endovascular approach to retinal vascu- nous (AV) sheathotomy as a surgical treat- University School of Medicine, lar occlusions. Endovascular recanaliza- ment for branch retinal vein occlusion.11,12 Boston, Mass (Dr Tang), and tion procedures such as percutaneous Investigators have suggested that by me- Medical College of Wisconsin, transluminal angioplasty and regional chanical lysis of the AV sheath, compres- Milwaukee (Dr Han). The authors do not have any thrombolytic delivery have been effective sion on the retinal venule might be re- commercial or proprietary in restoring blood flow in various organ lieved, leading to reversal of vein occlusion. 7-10 interest in any product or systems. Timely intervention often In the present study, we examined the instrument discussed in the results in significant recovery of func- technical feasibility and anatomical out- article. tion. We postulate that intraocular, come of AV sheathotomy.

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 MATERIALS AND METHODS mounted. In the case of the cannu- seconds via elevation of the infu- lated central retinal vein, tissue sec- sion bottle. Rabbit 1 underwent a bi- RETINAL VASCULAR tions were cut perpendicular to the lateral procedure and was killed im- CANNULATION: HUMAN axis of the optic nerve. Serial sec- mediately by intravenous injection CADAVER EYE MODEL tions were examined to (1) con- of pentobarbital/phenytoin solu- firm the entry of the nylon suture tion (1 mL per 5 kg). Two other rab- Human cadaver eyes were obtained into the vessel lumen, (2) identify bits underwent survival proce- from the Wisconsin Lions Eye Bank, any induced trauma to the endothe- dures. Fundus examinations by Milwaukee, and used within 48 lial lining due to cannulation, and indirect ophthalmoscopy were per- hours of expiration. The mean age (3) confirm the extent of vessel can- formed at weeks 1 and 2 after sur- was 80 years (age range, 63-91 nulation. gery. Fundus photographs were years). The anterior calotte was di- taken at week 2. The rabbits were vided from the posterior calotte at RETINAL VASCULAR then killed with pentobarbital/ the level of the equator. A total of 18 PENETRATION: ANIMAL phenytoin injection. The globes were cannulation procedures (17 eyes) EYE MODELS promptly enucleated. were performed. Adult hound dog eyes were op- Cannulations of branch reti- All animal research protocols were erated on during a nonsurvival ex- nal arterioles, branch retinal ven- reviewed and approved by the Ani- periment simultaneously conducted ules, central retinal arteries, and cen- mal Research Committee of the by cardiovascular physiologists study- tral retinal veins were performed. Medical College of Wisconsin, Mil- ing coronary blood flow. Anesthesia Under microscopic illumination, a waukee. In total, 6 eyes were oper- was maintained by intermittent doses bimanual technique with two 20- ated on: 4 eyes from 3 rabbits and 2 of intravenous pentobarbital (200 mg/ gauge microvitreoretinal (MVR) eyes from 2 dogs. The rabbit was se- kg) and barbital (26 mg/kg). Sys- blades was used to create an open- lected because of the presence of a temic medications relevant to our sur- ing in the vessel wall. Approxi- retinal vascular system. The dog was gical procedure included intravenous mately 3 to 4 disc diameters away selected because the caliber of its heparin. Surgical penetration of a reti- from the optic disc, an MVR blade retinal blood vessels more closely ap- nal venule was performed as de- was introduced to elevate a branch proximates that in humans. scribed earlier. Both eyes were enucle- retinal vessel from the surface of the Three-month-old New Zea- ated immediately after surgery. retina. Then, with the first MVR land white rabbits (2.4-3 kg) were After preservation, the poste- blade acting as a platform beneath obtained through the Animal Re- rior calotte was isolated. A surgical the retinal vessel, a second MVR search Facility at the Medical Col- blade was used to cut perpendicu- blade was used to make a small lon- lege of Wisconsin. Ketamine (44 mg/ lar to the direction of the retinal gitudinal arteriotomy/phlebotomy kg) and xylazine (5 mg/kg) were blood vessels to remove tissue 1⁄2 to incision. In the case of cannulation injected intramuscularly to pro- 1 disc diameter peripheral to the ves- of the central retinal artery/vein, the vide sedation and akinesia, respec- sel penetration site. The specimen same technique was used with the tively. Standard sterile surgical tech- was then embedded in paraffin, with arteriotomy/phlebotomy performed niques were employed. Illumination the cut edge marked for keratome on a first-order retinal arteriole/ was provided by the coaxial light sectioning (section thickness, 5 µm). venule immediately distal to the cen- source from an operating micro- For a distance of 1000 to 1500 µm tral bifurcation. A 10-0 black mono- scope. A 2.5-mm infusion cannula spanning the vessel penetration site, filament nylon suture held by a pair was placed through the pars plicata every fifth section was mounted. of smooth forceps was then used to at the inferotemporal quadrant. The Otherwise, every 10th to 100th sec- cannulate the retinal vessel through retina was visualized through an ir- tion was mounted. Serial sections the arteriotomy/phlebotomy open- rigating contact lens. An MVR blade were examined to determine the in- ing. Cannulation was considered suc- or a sharpened metal wire held by a tegrity of the retinal vasculature, as cessful if the nylon suture could be pair of intraocular forceps was in- well as the presence of associated advanced freely within the lumen of troduced through the pars plicata. retinal abnormalities. the blood vessel. A retinal vessel along the temporal After successful cannulation, myelin wing, at approximately a AV SHEATHOTOMY: HUMAN the specimen was preserved and third of a disc diameter from the op- CADAVER EYE MODEL photographed. Under a dissecting tic disc, was penetrated. (Because of microscope, a block of the poste- the similarity in color and size of the Human cadaver eyes were used as de- rior eye wall was isolated to in- retinal arterioles and venules, the scribedearlier.SevenAVsheathotomy clude the entire course of the can- retinal vessel selected for penetra- procedures (6 eyes) were performed. nulated retinal blood vessel. The tion was not specified as an arteri- Arteriovenous crossings were se- specimen was then embedded in par- ole or a venule.) Visualization of a lected from a first- or second-order affin. Tissue sections (5 µm thick) small burst of blood extravasating arteriole at a location where the were cut by a keratome in a direc- into the vitreous cavity indicated blood vessel was sufficiently filled tion roughly perpendicular to the successful penetration. Intraopera- with blood to allow for visuali- course of the retinal blood vessels. tive bleeding was controlled by rais- zation during dissection. Under Every 5th to 50th section was ing the intraocular pressure for 60 microscopic illumination, an MVR

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 blade was introduced to gently el- sheathotomy was identified. A block cannulation included: (1) insuffi- evate the arteriole on each side of the of posterior eye wall (approximately cient blood fill in the retinal ves- AV crossing from the surface of the 4 ϫ 4 mm) was isolated, with the site sels, precluding adequate visualiza- retina. Then, with a sawing motion of the AV sheathotomy located in the tion; (2) obscuration of view due to of the MVR blade, the AV sheath central portion of the tissue block. extravasated blood during dissec- was engaged. In one case, a pair Histological sections were prepared as tion; (3) inability of the nylon su- of intraocular scissors was used described earlier. For a distance of ture to gain entry through the arte- to divide the AV sheath. The AV 1000 to 1500 µm spanning the site of riotomy/phlebotomy sites; (4) false sheathotomy was considered suc- dissection, every 5th section was passage into subretinal space after cessful if the MVR blade or intra- mounted; otherwise, every 10th to multiple attempts; and (5) folding ocular scissors could be passed freely 100th section was mounted. Serial and distortion of the retina. Histo- between the arteriole and the ven- sections were examined to (1) con- logical examination of successfully ule. The branching patterns of the firm complete lysis of AV adhesion, cannulated specimens demon- retinal blood vessels were re- (2) identify any induced trauma to strated a nylon suture fragment in- corded in the form of a carefully retinal vessels, and (3) identify any inside the retinal blood vessel with no drawn sketch to facilitate identi- duced trauma to the adjacent retinal observable damage to the endothe- fication of the sites of the AV tissue. lial lining (Figure 3). In the case sheathotomies during histological of cannulation of the central retinal preparation. RESULTS vein, the nylon suture fragment After successful AV sheathot- could be identified in the central reti- omy, the specimen was preserved nal vein at the level of the lamina RETINAL VASCULAR and photographed. Under a dissect- cribrosa (Figure 4). ing microscope, the site of the AV CANNULATION: HUMAN CADAVER EYE MODEL RETINAL VASCULAR Cannulations of branch retinal ar- PENETRATION: ANIMAL Summary of Results terioles, branch retinal venules, and EYE MODELS central retinal veins were success- No. of Successful fully performed (Table). In cases of Operative Results Procedures/ successful cannulation of branch Total retinal vessels, the nylon suture Surgical penetration of retinal Procedure* Procedures could be advanced with ease to- blood vessels was successfully ac- Branch retinal arteriole 7/9 ward the center of the optic disc complished in 5 of 6 eyes. A small cannulation (Figure 1). However, the suture amount of bleeding from the pen- Branch retinal venule 1/3 would not bend sufficiently to al- etration site was immediately cannulation Central retinal artery 0/2 low further advancement into the halted by elevation of intraocular cannulation optic nerve. In cases of successful pressure. Hemostasis was main- Central retinal vein 2/4 cannulation of the central retinal tained when the intraocular pres- cannulation vein, the suture could be advanced sure was brought back to normal. Retinal vascular penetration 5/6 with ease into the optic nerve In dog 2, a rapidly developing in- Arteriovenous sheathotomy 4/7 (Figure 2). The suture was then ob- traoperative vitreous hemorrhage served to emerge from the stump of (presumably from the sclerotomy *Retinal vascular penetration was performed on an animal eye model; all other procedures the retrobulbar optic nerve. Fac- site) prevented successful penetra- were performed on human cadaver eye models. tors responsible for unsuccessful tion of the retinal vessel.

Figure 1. Cannulation of human branch retinal arteriole with a 10-0 nylon Figure 2. Cannulation of human central retinal vein. A black nylon suture has suture. A black suture has been introduced through an arteriotomy (arrow) been introduced into the lumen of the central retinal vein. The trailing end of into the vessel lumen and advanced to the optic disc. the suture is seen anterior to the optic disc (arrow).

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 Figure 3. Histological micrograph after cannulation of human branch retinal Figure 4. Histological micrograph after cannulation of human central retinal arteriole demonstrates a suture fragment inside the lumen of a retinal vein demonstrates a suture fragment in the central retinal vein at the level of arteriole (hematoxylin-eosin, original magnification ϫ40). the lamina cribrosa (hematoxylin-eosin, original magnification ϫ16).

Figure 5. Histological micrograph of rabbit retina immediately after vascular Figure 6. Histological micrograph of rabbit retina 2 weeks after vascular penetration (left eye of rabbit 1). Thrombus formation is observed at the site penetration (rabbit 2). The retinal vasculature is completely patent. A few of penetration (arrow) of a retinal venule. Surrounding preretinal hemorrhage erythrocytes in the vitreous cavity and a few subretinal macrophages are is present (hematoxylin-eosin, original magnification ϫ40). observed (hematoxylin-eosin, original magnification ϫ40).

Immediate Anatomical Outcome tological examination of the eye from degree or a retinal blood vessel was rabbit 2 demonstrated a com- transected. Histological examina- Four eyes were enucleated promptly pletely patent retinal vasculature tion of successfully operated speci- after surgery. Histological evalua- (Figure 6). Evidence of previous mens demonstrated a complete ly- tion demonstrated thrombus forma- surgical trauma included a few eryth- sis of the AV adhesion (Figure 7). tion in a retinal arteriole (left eye of rocytes in the vitreous cavity and a However, in the case performed with rabbit 1, Figure 5), or a retinal ven- few subretinal macrophages adja- intraocular scissors, a laceration was ule (right eyes of rabbit 1 and dog cent to a small outer-layer retinal de- observed on the retinal venule wall. 1). In 2 cases (right and left eyes of hiscence. Histological findings in In 2 cases, a full-thickness retinal rabbit 1), the vascular penetration rabbit 3 were similar to those in rab- break near the site of dissection was site could be identified (Figure 5). bit 2. observed. In dog 2, except for the presence of vitreous hemorrhage, histological AV SHEATHOTOMY: HUMAN COMMENT findings were normal. CADAVER EYE MODEL Endovascular recanalization therapy Survival Surgery Arteriovenous sheathotomy was suc- has demonstrated efficacy for vas- cessful in 4 of 7 procedures (6 eyes). cular occlusions in various organ In the 2 eyes from animals under- During the dissection, it was ob- systems, including the heart, brain, going survival surgery, fundus ex- served that the adhesion between the and extremities.7-10 Endovascular amination at week 1 and 2 demon- arteriole and the venule was surpris- therapy can help reestablish blood strated a normal-appearing retina ingly strong, so much so that the ad- flow by mechanical or pharmaco- with a clear vitreous cavity in one jacent retina was often dragged when logical means. Percutaneous trans- (rabbit 2), and a normal-appearing the AV sheath was being engaged. luminal angioplasty is the classic me- retina with an inferior vitreous hem- In unsuccessful cases, the retina was chanical approach in which the orrhage in the other (rabbit 3). His- either dragged to an unacceptable thrombus or the atherosclerotic

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 demonstrated in other organ systems.9 Delivery of thrombolytics into the ophthalmic artery via a trans- femoral route has been reported to be effective in some cases of central retinal artery occlusion.14,15 Re- cently, with the assistance of a mi- cromanipulator, intraocular injection of thrombolytics into a branch retinal venule has been reported for central retinal vein occlusion.16 Our animal study examined the issue of gaining surgical access into the retinal vasculature under in vivo conditions. Using a manual technique, a small, controlled penetration of a retinal vessel can be accomplished without necessarily causing Figure 7. Histological micrograph of a human retina after arteriovenous sheathotomy. Adhesion between persistent thrombosis at the pen- the arteriole (arrow) and the venule (arrowhead) has been severed (hematoxylin-eosin, original magnification ϫ40). etration site. Such a maneuver is es- sential to obtain mechanical access plaque is physically disrupted by an propylene sutures were too floppy for into the retinal vasculature. The pos- angioplasty balloon.10 Alterna- reliable entry into the blood vessel. sibility of an uncontrolled intra- tively, regional infusion of a throm- The degree to which a flexible stylet operative hemorrhage from the bolytic agent can result in pharma- can reach various locations in a injured retinal vessel was a con- cological lysis of the thrombus.8,9 branch retinal vessel is important be- cern. In each case, hemostasis was The unique opportunity to visual- cause pathological entities such as ve- maintained after raising the intra- ize and access the retinal vascula- nous thrombi and thromboemboli are ocular pressure for 1 minute. The pre- ture during vitreous surgery led us often localized to specific sites within sent study is limited to penetration of to consider an intraocular, endovas- the vasculature.5,13 Starting from a dis- the retinal vasculature using a single- cular approach to retinal vascular oc- tal branch retinal vessel, we were un- handed technique. In the future, a clusions. The present study on can- able to navigate the 10-0 nylon su- bimanual technique could be em- nulation of retinal blood vessels ture beyond the center of the optic ployed: a sharp instrument in one demonstrates the technical feasibil- disc, because the nylon suture was not hand could penetrate a retinal ves- ity of (1) mechanical access into the flexible enough to make an acute turn sel, and a blunt stylet or microcath- retinal vasculature and (2) the in- from the plane of the fundus into the eter in the other could cannulate the troduction and advancement of a axis of the optic nerve. However, we vessel. Maintenance of hemostasis flexible stylet to a potentially de- were able to cannulate the central reti- would certainly be critical and could sired site of action. nal vein by accessing a first-order ven- be accomplished by adjustment of in- During the preliminary phase ule on the optic disc. Successful can- traocular pressure and other tech- of the study, we experimented with nulation of the central retinal vein is niques such as intravitreal injection a variety of materials for penetrat- significant because the obstructing of a perfluorocarbon liquid.17 ing retinal blood vessel walls, in- thrombus in central retinal vein oc- Our study of AV sheathotomy cluding nylon sutures, thin metal clusion has been localized to the level addresses the peculiar anatomy of wires, glass micropipettes, and MVR of the lamina cribrosa.6 A desirable AV crossings and a potentially vi- blades. We noted that the penetrat- stylet material in the future should able surgical technique for branch ing tip of the material must be ex- therefore be flexible enough to con- retinal vein occlusion. At the site of tremely sharp to allow for reliable form to the curves and turns of the an AV crossing, the arteriole and the penetration without significant dis- retinal vasculature, but rigid enough venule share a common adventitial tortion to the adjacent retina. to allow for navigation without kink- sheath, with the venule often appar- Selection of stylet material is an- ing and mechanical disruption of the ently compressed, or its course other issue integral to successful can- thrombus. acutely diverted, by the arteri- nulation. In the preliminary phase, we In addition, successful cannu- ole.18,19 It has therefore been specu- experimented with 10-0 nylon, 11-0 lation with a flexible stylet leads to lated that thrombus formation in the nylon, 11-0 polyester (Mersilene; the consideration of future cannu- retinal venule is caused by chronic Ethicon Inc, Somerville, NJ) and 10-0 lations performed with a microcath- compression from the adjacent ar- polypropylene sutures (Prolene; Ethi- eter, through which thrombolytic teriole.20 A case series suggested that con Inc), and found that 10-0 nylon agents can be infused. Regional AV sheathotomy might lead to de- sutures provided the most reliable thrombolytic infusion as potential compression of the retinal venule cannulation. The 11-0 polyester su- therapy for retinal vascular occlu- and reversal of branch retinal vein tures had a tendency to bend and kink sion deserves important consider- occlusion.11 Histological data were inside the blood vessel; the 10-0 poly- ation, because its efficacy has been not available to demonstrate the ana-

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 tomical result of AV sheathotomy. Accepted for publication September 10, of venous thromboembolic disease. Surg Clin North Am. 1992;72:969-989. The present study shows that com- 1999. 8. Hurst RW. Revascularization in the central ner- plete lysis of the AV sheath, al- This study was supported in part vous system. In: Baum S, Pentecost MJ, eds. by Research to Prevent Blindness Inc, Abrams’ Angiography: Interventional Radiology. though possible, is often difficult be- 4th ed. Boston, Mass: Little Brown & Co; 1996: cause of the tight adhesion between New York, NY. 745-764. the arteriole and the venule. In a re- Presented in part at the Associa- 9. Valji K, Bookstein JJ. Thrombolysis: clinical applications. In: Baum S, Pentecost MJ, eds. view of the anatomy of AV cross- tion for Research in Vision and Oph- Abrams’ Angiography: Interventional Radiol- ings, Seitz19 demonstrated that in- thalmology annual meeting, Ft Lau- ogy. 4th ed. Boston, Mass: Little Brown & Co; creased fibrous connections exist derdale, Fla, March 15, 1997. 1996:132-159. 10. Landau C, Lange RA, Hillis LD. Percutaneous trans- between the arteriole and the ven- Reprints: William M. Tang, MD, luminal coronary angioplasty. N Engl J Med. 1994; ule. Sometimes, the arteriole and the Department of Ophthalmology, Bos- 330:981-993. ton University, 715 Albany St, Bos- 11. Opremcak EM, Bruce RA. Surgical decompres- venule share a common medial wall sion of branch retinal vein occlusion via arterio- that is only about 15 µm thick. It is ton, MA 02118-2526 (e-mail: venous crossing sheathotomy. Retina. 1999;19: therefore not surprising that lacera- [email protected]). 1-5. 12. Osterloh MD, Charles S. Surgical decompres- tion on the venule wall was ob- sion of branch retinal vein occlusions. Arch Oph- served in one of our specimens. Al- thalmol. 1988;106:1469-1471. REFERENCES 13. Ros MA, Magargal LE, Uram M. Branch retinal- though AV sheathotomy might artery obstruction: a review of 201 eyes. Ann Oph- nevertheless be a feasible surgical thalmol. 1989;21:103-107. technique, we found complete lysis 1. Mitchell P, Smith W, Chang A. Prevalence and as- 14. Richard G, Lerche RC, Knospe V, Zeumer H. Treat- sociations of retinal vein occlusion in Australia: ment of retinal arterial occlusion with local fibri- of the AV sheath to be a generally the Blue Mountains Eye Study. Arch Ophthalmol. nolysis using recombinant tissue plasminogen ac- traumatic event when using cur- 1996;114:1243-1247. tivator. Ophthalmology. 1999;106:768-773. rently available instrumentation. 2. The Central Vein Occlusion Study Group. Natural 15. Schmidt D, Schumacher M, Wakhloo AK. Micro- history and clinical management of central reti- catheter urokinase infusion in central retinal ar- In conclusion, multiple surgi- nal vein occlusion. Arch Ophthalmol. 1997;115: tery occlusion. Am J Ophthalmol. 1992;113:429- cal techniques aimed at assisting re- 486-491. 434. 3. Atebara NH, Brown GC, Cater J. Efficacy of ante- 16. Weiss JN. Treatment of central retinal vein occlu- canalization of occluded retinal vas- rior chamber paracentesis and carbogen in treat- sion by injection of tissue plasminogen activator culature have been evaluated. A ing acute nonarteritic central retinal artery occlu- into a retinal vein. Am J Ophthalmol. 1998;126: surgical approach to retinal vascu- sion. Ophthalmology. 1995;102:2029-2034. 142-144. 4. Perraut LE, Zimmerman LE. The occurrence of 17. Merrill PT, LoRusso FJ, Lomeo MD, Saxe SJ, Khan lar occlusions has become more fea- glaucoma following occlusion of the central reti- MM, Lambert HM. Surgical removal of subfoveal sible and deserves further investi- nal artery: a clinicopathologic report of six new choroidal neovascularization in age-related macu- gation. Technological advances such cases with a review of the literature. Arch Oph- lar degeneration. Ophthalmology. 1999;106:782- thalmol. 1959;61:845-865. 789. as the design of a flexible stylet or 5. Frangieh GT, Green WR, Barraquer-Somers E, 18. Weinberg D, Dodwell DG, Fern SA. Anatomy of ar- microcatheter are desirable to ac- Finkelstein D. Histopathologic study of nine branch teriovenous crossings in branch retinal vein oc- retinal vein occlusions. Arch Ophthalmol. 1982; clusion. Am J Ophthalmol. 1990;109:298-302. complish such surgical goals. Once 100:1132-1140. 19. Seitz R. The crossing phenomenon. In: The Reti- the retina vasculature is accessed, a 6. Green WR, Chan CC, Hutchins GM, Terry JM. Cen- nal Vessels. St Louis, Mo: CV Mosby; 1964:20- variety of therapeutic approaches, tral retinal vein occlusion: a prospective histo- 74. pathologic study of 29 eyes in 28 cases. Trans Am 20. Duker JS, Brown GC. Anterior location of the cross- both mechanical and pharmacologi- Ophthalmol Soc. 1981;79:371-422. ing artery in branch retinal vein obstruction. Arch cal, can be pursued. 7. Greenfield LJ, DeLucia A III. Endovascular therapy Ophthalmol. 1989;107:998-1000.

100 Years Ago in the ARCHIVES

A look at the past...

he putting into practice by a beginner of the teaching received from a first-class master, may prove interesting and instructive to some of the readers of these ARCHIVES, hence my presentation to them of this report of my first one Thundred cataract extractions. These have been performed at several of the general and private hospitals of this city, and at the private residence of a good many of the patients, the nursing often leaving a good deal to be desired, making the fair amount of success with which they have been attended all the more satisfactory. This I attribute, in great part, to the valuable experience I acquired during my three years’ connection with the New York Ophthalmic and Aural Institute, during which I had the opportunity, not only of assisting at almost all the operations of such an expert as Dr Knapp, but also of following their after-treatment to the end...

Reference: Finlay CE. Series of one hundred cases of cataract extraction. Arch Ophthalmol. 1900;29:54.

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