Abstract
Abstract: :
Purpose: To characterize diabetic retinopathy (DR) in a colony of aged, diabetic rhesus monkeys, and to investigate the contribution of, and functional consequences of, ischemia in these monkeys. Methods: Noninvasive measures (indirect ophthalmoscopy, applanation tomography, color photography, fluorescein and ICG angiography, ganzfeld and multifocal electroretinograms, and color Doppler ultrasounds of ocular and carotid artery flow velocities) and histology and immunohistochemistry (ADPase to stain viable retinal capillaries, HSPG to stain viable choroidal capillaries, NSE to stain neutrophils) of eyes harvested immediately after euthanasia were performed on diabetic monkeys and age-similar normal monkeys. Results: To date, 30 monkeys have been studied: 20 with diabetes and 10 without. Typical diabetic changes included capillary dropout, cotton wool spots, intraretinal hemorrhages and microaneurysms. Systemic hypertension was an extremely important variable: histologic evidence of retinopathy was found in 6/8 hypertensive diabetic animals, compared to 0/5 normotensive diabetic animals (<0.027). Glaucoma was a co-morbid condition in 23% (3/13) of the diabetic monkeys but in none of the normal monkeys. Four animals with advanced retinopathy had extensive capillary dropout centered on the optic disk and extending to and bisecting the fovea. Despite this extensive dropout, none of the animals had neovascularization, and microaneurysms were small and infrequent. Extensive choriocapillaris dropout was seen in a monkey with diabetes and macular drusen. Conclusion: DR in this colony is similar but not identical to DR found in humans. We have documented the importance of hypertension, just recently formally recognized in humans. Diabetes may be a real risk factor for glaucoma, i.e. not an artifact of sampling bias as has been suspected in humans.
Keywords: 388 diabetic retinopathy • 316 animal model • 345 choroid