Abstract
BackgroundPatients with retinal diseases frequently complain of poor visual function even when visual acuity is relatively unaffected. This clinical finding has been attributed to deficits in contrast sensitivity (CS). The purpose of our study was to evaluate the CS in patients with clinical and genetic diagnosis of inherited retinal degeneration (IRD) and relatively preserved visual acuity.MethodsSeventeen patients (30 eyes) with IRD and visual acuity of 20/40 or better, and 18 controls (18 eyes) without any ocular condition underwent slit lamp examination, visual acuity testing via standard Snellen chart testing, CS testing via the Quick Contrast Sensitivity Function (QCSF), and Spectral Domain Optical Coherence Tomography (SD-OCT). CS were measured at 1.0, 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (cpd). T tests with general estimated equations were used to compare CS between groups. Wald chi square followed by pairwise comparisons was used to compare CS between multiple groups.ResultsWe included 12 patients with rod-cone dystrophy (RCD), 3 patients with Stargardt disease (STGD) and 2 patients with Best disease. Patients with IRD had significantly worse CS than controls (p < 0.001) in all spatial frequencies. Patients with STGD had more marked deficits in CS than patients with Best disease (p < 0.001) and RCD (p < 0.001) despite having similar visual acuities.ConclusionPatients with IRD, especially patients with STGD with relatively preserved visual acuity have marked deficits in CS when measured across a range of spatial frequencies. We recommend that clinical trials for STGD incorporate CS measured over a range of spatial frequencies as a secondary clinical endpoint for monitoring visual function. CS may provide an explanation for complaints of visual dysfunction when visual acuity is not significantly altered.
Highlights
Patients with retinal diseases frequently complain of poor visual function even when visual acuity is relatively unaffected
With the advent of new methods such as the Quick Contrast Sensitivity Function (QCSF) that provide a more comprehensive evaluation of contrast sensitivity (CS) losses at a greater number of contrast and spatial frequency combinations [23], this study aimed to compare CS deficits among patients with both a clinical and a genetic diagnosis of an inherited retinal degeneration (IRD) and normal controls who presented with visual acuity (VA) acuities better than 20/40
There were 12 patients with rod-cone dystrophy (RCD) caused by pathogenic variants in eight different genes (Table 1), three patients with Stargardt disease (STGD) caused by two pathogenic variants in the ABCA4 and two patients with Best disease caused by at least one pathogenic variant in the BEST1
Summary
Patients with retinal diseases frequently complain of poor visual function even when visual acuity is relatively unaffected. This clinical finding has been attributed to deficits in contrast sensitivity (CS). The purpose of our study was to evaluate the CS in patients with clinical and genetic diagnosis of inherited retinal degeneration (IRD) and relatively preserved visual acuity. Patients with inherited retinal degeneration (IRD) often complain of poor central vision, despite having a visual acuity near 20/20 [1,2,3]. There are a number of ongoing clinical trials for patients with IRD where the primary outcome measure is visual acuity improvement or stability [4,5,6]. Others such as Yioti et al described structural changes observed on Spectral Domain Optical Coherence Tomography (SD-OCT) corresponding to deficits of CS in patients with retinitis pigmentosa [15]
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