The relationship between perifoveal capillary ring alterations and visual acuity in diabetic retinopathy

Background/Aim. The relationship between the foveal avascular zone (FAV) and visual acuity (VA) in retinal dis-eases remains a matter of discussion. The aim of this study was to determine the impact of diabetic macular ischemia (DMI) on VA through the analysis of the perifoveal capil-lary network in various stages of diabetic retinopathy -DR (non-proliferative diabetic retinopathy - NPDR and prolif-erative diabetic retinopathy - PDR). Methods. Qualitative and quantitative analysis of 143 angiograms of patients with different stages of DR was performed. The degree of macu-lar ischemia was assessed by the analysis of 2 parameters: perifoveal capillary ring, ie, the FAZ outline irregularity, and capillary loss. Finally, a comparison was made between the degree of macular ischemia with the best-corrected VA, de-pending on macular thickness. Results. In the eyes with mild and moderate NPDR, without significant macular thickening, no statistically significant decrease in VA caused by macular ischemia was noticed (p = 0.81). Opposite, in a subgroup with severe NPDR and PDR, without significant macular thickening, a statistically significant difference was presented among eyes with moderate and severe macular is- chemia compared to eyes with lower grades of macular is-chemia (p = 0.021 and p = 0.018, respectively). In the eyes with moderate NPDR and mild macular ischemia, the in-crease in macular thickness resulted in a statistically insignif-icant decrease in VA compared to eyes with a normal macu-lar thickness (p = 0.088). However, in the eyes with severe NPDR, every pathological increase in macular thickness caused a statistically significant decrease in VA, regardless of the degree of macular ischemia (p = 0.018-0.040). A similar relationship was also found in the eyes with PDR (p = 0.017-0.042). In the eyes with a statistically significant de-crease in VA, most of the examined eyes (98%) had the FAZ outline irregularity in the nasal perifoveal subfield. Conclusion. In the absence of significant macular thicken-ing, the destruction of one-half of the perifoveal capillary network, or greater, is associated with reduced VA. The lo-cation of macular ischemic changes in the nasal parts of the perifoveal capillary ring plays a crucial role in its effects on visual function.