Abstract
Purpose :
To compare various photocoagulation patterns delivered to preserve non-ischmic peripheral retina in diabetes. To determine if there is an optimal PRP pattern with regard to two criteria; the area photocoagulated and the area of retina which develops ischemia over time. Our model is a probabilistic treatment of initial capillary occlusion followed by an adverse feedback cycle of capillary occlusion. We addressed patterns of retinal burns including retinal segmentation via photocoagulation lines producing oxygenated barriers to the propagation of capillary occlusion. Unlike traditional PRP done on ischemic retinal areas to treat neovascularization, we explore a new application of photocoagulation, PPRP, to prevent propagation of peripheral ischemia in diabetic retinopathy rather than to treat existing ischemia.
Methods :
Comparisons were made of the area of retinal photocoagulation delivered in the various treatment patterns as well as of the progression of ischemic retina over time within our Compucell3D computational model of progression of diabetic retinopathy. Various photocoagulation spot sizes and patterns were modelled with each burn producing a local area of oxygenation. On each PRP pattern many replications were run on a supercomputer and outputs of the resulting ischemic areas were produced.
Results :
The modeling results show that traditional spot size and distribution allow continued propagation of capillary occlusion as well as having a compatatively large area of photocoagulated retina. Certain other distributions of photocoagulation burns were superior both in terms of minimum treated area and in terms of minimizing propagation of capillary occlusion within the model. The optimal pattern requires production of linear areas of oxygenation (burns), which may be produced by discrete burns, bridging between the areas of oxygenation normally present around patent arterioles and venules.
Conclusions :
There are patterns of photocoagulation, PPRP patterns, which, when applied to intact capillary netwroks in diabetics, can prevent or minimize the propagation of capillary ischemia in a way superior to the burn patterns delivered by conventional PRP. Early treatment of diabetics suffering some peripheral ischemia may prevent progression to neovascularization. Therapeutically this would require advances in current delivery of PRP and minimization of the complications of PRP.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.