Associations Between Visual Functions and Severity Gradings, Corneal Scatter, or Higher-Order Aberrations in Fuchs Endothelial Corneal Dystrophy.

Purpose: The purpose of this study was to investigate the associations between visual function and severity grading, corneal scatter, or higher-order aberrations (HOAs) in patients with Fuchs endothelial corneal dystrophy (FECD). Methods: This observational case series study included 49 eyes of 27 patients with FECD and 10 eyes of 10 healthy individuals. We evaluated corrected distance visual acuity (CDVA) using Landolt-C and Early Treatment Diabetic Retinopathy Study charts and contrast sensitivity using the CSV-1000E chart and CSV-1000RN letter chart. We analyzed the associations between visual function and explanatory variables, including age, modified Krachmer grade, central corneal thickness (CCT), anterior segment optical coherence tomography (AS-OCT)-based grade, HOAs, intraocular straylight, and corneal densitometry. We additionally conducted receiver operating characteristic (ROC) analysis to identify the corneal densitometry thresholds for decreased visual function. Results: There were significant associations between visual function and the modified Krachmer grade, CCT, AS-OCT-based grade, HOAs, intraocular straylight, and corneal densitometry. A modified Krachmer grade ≥ 3 was identified as a threshold for decreased visual function. Multivariate analysis showed that corneal densitometry was significantly associated with all visual function parameters, and HOAs were significantly associated with CDVA but not with contrast sensitivity. ROC analysis revealed that corneal densitometry of the posterior layer at 0 to 2 mm ≥ 10 grayscale units (GSU), was identified as a threshold for decreased visual function. Conclusions: HOAs, forward and backward light scatter affected visual function, with backward light scatter being the most influential. In patients with FECD, modified Krachmer grade ≥ 3 and corneal densitometry ≥ 10 GSU were thresholds for visual disturbance.

Efficient measurements for the dynamic range of human lightness perception.

PURPOSE: Patients with an eye disease often report nyctalopia, hemianopia, and/or photophobia. We hypothesized that such symptoms are related to the disease impacting the dynamic range of lightness perception (DRL). However, there is currently no standardized approach for measuring DRL for clinical use. We developed an efficient measurement method to estimate DRL. STUDY DESIGN: Clinical trial METHODS: Fifty-five photophobic patients with eye disease and 46 controls participated. Each participant judged the appearance of visual stimuli, a thick bar with luminance that gradually changed from maximum to minimum was displayed on uniform background. On different trials the background luminance changed pseudo-randomly between three levels. The participants repeatedly tapped a border on the bar that divided the appearance of grayish white/black and perfect white/black. We defined the DRL as the ratio between the luminance values at the tapped point of the border between gray and white/black. RESULTS: The mean DRL of the patients was approximately 15 dB, significantly smaller than that of the controls (20 dB). The center of each patient's DRL shift depending on background luminance, which we named index of contextual susceptibility (iCS), was significantly larger than controls. The DRL of retinitis pigmentosa was smaller than controls for every luminance condition. Only the iCS of glaucoma was significantly larger than controls. CONCLUSIONS: This measurement technique detects an abnormality of the DRL. The results support our hypothesis that the DRL abnormality characterizes lightness-relevant symptoms that may elucidate the causes of nyctalopia, hemeralopia, and photophobia.