Mesopic Visual Acuity in Type2 Diabetes without Retinopathy

Abstract

PurposeToday, the information about the extent to which mesopic visual acuity (VA) is altered in diabetics without retinopathy is lacking. The purpose of this study was to evaluate distance high contrast VA (HC‐VA) and low contrast VA (LC‐VA) under mesopic luminance conditions in type 2 diabetics without any signs of retinopathy.MethodsThirty‐six control subjects and twenty‐three diabetics (well controlled glucose level) without retinopathy (mean onset duration 8.5 ± 4.42 yrs) were tested. All subjects had best corrected VA of 20/20 or better. VA was measured using the HC (96% contrast) and LC (10% contrast) Baily‐Lovie charts under photopic (85 cd/m2) and mesopic (0.10 cd/m2) luminance conditions with best distance correction worn. The subject was left to dark adapt for 10 minutes in the dark before testing mesopic VA.ResultsMean photopic VA's (logMAR) were significantly worse in diabetics than controls (HC‐VA 0.03 ± 0.08 and −0.03 ± 0.08, p < 0.01; LC‐VA 0.17 ± 0.08 and 0.11 ± 0.11, p < 0.05, respectively). Mean mesopic HC‐VA was also worse in diabetics than controls (0.56 ± 0.11 and 0.48 ± 0.09, p < 0.05, respectively), but with less extent than photopic VA. Mesopic LC‐VA was not significantly different between diabetics and controls (0.94 ± 0.11 and 0.91 ± 0.06).ConclusionsDistance photopic high contrast and low contrast VA, and mesopic HC‐VA were able to detect the worsening of VA in type 2 diabetics before any signs of retinopathy can be detected.