A Computational Model of Peripheral Photocoagulation for the Prevention of Progressive Diabetic Capillary Occlusion

Abstract

We developed a computational model of the propagation of retinal ischemia in diabetic retinopathy and analyzed the consequences of various patterns and sizes of burns in peripheral retinal photocoagulation. The model addresses retinal ischemia as a phenomenon of adverse local feedback in which once a capillary is occluded there is an elevated probability of occlusion of adjacent capillaries resulting in enlarging areas of retinal ischemia as is commonly seen clinically. Retinal burns of different sizes and patterns, treated as local oxygen sources, are predicted to have different effects on the propagation of retinal ischemia. The patterns of retinal burns are optimized with regard to minimization of the sum of the photocoagulated retina and computer predicted ischemic retina. Our simulations show that certain patterns of retinal burns are effective at preventing the spatial spread of ischemia by creating oxygenated boundaries across which the ischemia does not propagate. This model makes no statement about current PRP treatment of avascular peripheral retina and notes that the usual spot sizes used in PRP will not prevent ischemic propagation in still vascularized retinal areas. The model seems to show that a properly patterned laser treatment of still vascularized peripheral retina may be able to prevent or at least constrain the propagation of diabetic retinal ischemia in those retinal areas with intact capillaries.

Adaptive optics imaging of the human retina

“…AO retinal imaging is providing an improved ability to precisely characterize capillary velocity and diameter, which together determine blood flow. These measurements hold forth the promise of improved retinal capillary blood flow and shear stress and improved understanding of how they impact the eye (Fu et al, 2016; Gast et al, 2016; Lu et al, 2016b).…”

Advancing treatment of retinal disease through in silico trials

“…While practice has shown the efficiency of the procedure, its mechanisms of action remain unclear. It is thought that the procedure acts by reducing the oxygen consumption of the photoreceptors affected by the laser-induced burn [93,115]. However, effects of the therapy on blood flow have been observed [93].…”

“…The burn patterns used in panretinal photocoagulation are also subject to debate. Gast et al investigated the effects of different patterns on the propagation of ischaemia due to capillary occlusion [115]. The model showed how different burn patterns affect the propagation of ischaemia and suggested that targeting the non-ischaemic peripheral retina with appropriate patterns may be effective at containing it.…”

“…However, when modelling certain diseases or interventions, incorporating additional details may be required, e.g. details of the haemodynamics in capillaries (see figure 3) and physiology [60,115] or retinal morphology [83,239].…”

Multiscale Model of Antiviral Timing, Potency, and Heterogeneity Effects on an Epithelial Tissue Patch Infected by SARS-CoV-2

“…In ABMs, the agents are capable of independent decision making according to assigned attributes and conditions [ 22 , 23 ]. Cellular ABMs can introduce tissue heterogeneity to models by their very nature, as cells are individually modeled and can differ from one another, space itself is a model component [ 24 , 25 , 26 , 27 , 28 ]. A recent report on comparative biology immune ABM ( CBIABM ) has presented a model of mechanism-based differences in bat and human immune systems and discusses the consequences of these differences on disease manifestation [ 29 ].…”