The Significance of the Discordant Occurrence of Lens Tumors in Humans versus Other Species.

PURPOSE: The purpose of this study was to determine in which species and under what conditions lens tumors occur. DESIGN: A review of databases of available human and veterinary ocular pathologic material and the previously reported literature. PARTICIPANTS: Approximately 18 000 patients who had ocular surgical specimens submitted and studied at the University of Wisconsin School of Medicine and Public Health between 1920 and 2014 and 45 000 ocular veterinary cases from the Comparative Ocular Pathology Laboratory of Wisconsin between 1983 and 2014. METHODS: Material in 2 major archived collections at the University of Wisconsin medical and veterinary schools were studied for occurrence of lens tumors. Tumor was defined as a new growth of tissue characterized by progressive, uncontrolled proliferation of cells. In addition, cases presented at 3 major eye pathologic societies (Verhoeff-Zimmerman Ophthalmic Pathology Society, Eastern Ophthalmic Pathology Society, and The Armed Forces Institute of Pathology Ophthalmic Alumni Society) from 1975 through 2014 were reviewed. Finally, a careful search of the literature was carried out. Approval from the institutional review board to carry out this study was obtained. MAIN OUTCOME MEASURES: The presence of tumors of the lens. RESULTS: The database search and literature review failed to find an example of a lens tumor in humans. In contrast, examples of naturally occurring lens tumors were found in cats, dogs, rabbits, and birds. In the veterinary school database, 4.5% of feline intraocular and adnexal neoplasms (234/5153) were designated as feline ocular posttraumatic sarcoma, a tumor previously demonstrated to be of lens epithelial origin. Similar tumors were seen in rabbit eyes, a bird, and in a dog. All 4 species with lens tumors had a history of either ocular trauma or protracted uveitis. The literature search also revealed cases where lens tumors were induced in zebrafish, rainbow trout, hamsters, and mice by carcinogenic agents (methylcholanthrene, thioacetamide), oncogenic viruses (SV40, HPV-16), and genetic manipulation. CONCLUSIONS: Our results suggest that lens tumors do not occur in humans. In contrast, after lens capsule rupture, a lens tumor can occur in other species. We hypothesize that a genetic mechanism exists that prevents lens tumors in humans.

Targeted photocoagulation of peripheral ischemia to treat rebound edema.

INTRODUCTION: Peripheral retinal ischemia not detectable by conventional fluorescein angiography has been proposed to be a driving force for rebound edema in retinal vein occlusions. In this report, we examine the treatment of peripheral retinal ischemia with targeted retinal photocoagulation (TRP) to manage a patient's rebound edema. METHODS: To assess the extent of peripheral nonperfusion, an Optos 200Tx device was used. To target the treatment to peripheral ischemia areas, a Navilas Panretinal Laser was used. RESULTS: A 64-year-old male with a central retinal vein occlusion and a visual acuity 20/300, and central macular thickness 318 µm presented with rubeosis. Angiography revealed extensive peripheral nonperfusion. Despite TRP to areas of irreversible ischemia, after 2 months, he continued show rubeosis and rebound edema. Additional TRP laser was repeatedly added more posteriorly to areas of reversible nonperfusion, resulting in eventual resolution of rubeosis and edema. CONCLUSION: In this study, we demonstrate the use of widefield imaging with targeted photo-coagulation of peripheral ischemia to treat rebound edema, while preserving most peripheral vision. In order to treat rebound edema, extensive TRP, across reversible and nonreversible areas of ischemia, had to be performed - not just in areas of nonreversible peripheral ischemia. These areas need to be mapped during episodes of rebound edema, when ischemia is at its maximum. In this way, by doing the most TRP possible, the cycle of rebound edema can be broken.