EXPERIMENTAL-MODELS AND THEIR USE IN STUDIES OF DIABETIC RETINAL MICROANGIOPATHY

Diabetes produces dramatic changes in retinal microvasculature, trigge ring endothelial cell proliferation and microaneurysms. Capillaries be come weakened, releasing blood into vitreal and retinal spaces. Photor eceptors become occluded and separated from the choriocapillaris, resu lting in visual acuity decline, detachment and cell death. Several mod els have been developed that have proved useful for the study of this disease, resulting in a better understanding of the processes involved . Streptozotocin treatment affects the pancreatic beta cells, rapidly reducing them until insulin is no longer synthesized in sufficient amo unts. The galactosemic model shifts metabolism away from glucose, incr easing aldose reductase and retinal polyol metabolism. Finally, two we eks of cycled oxygen from high to low tension every 24 hours, followed by return to room air, triggers microangiogenesis in developing retin as. Use of these models, separately or in combination, as well as elec troretinographic analysis, has begun to reveal the events taking place as diabetic retinopathy progresses. Endothelial cells become separate d from pericytes as basement membranes thicken, and vascular endotheli al growth factor increases, triggering their proliferation. Finally, e arly changes occurring within photoreceptors can now be studied.