Willliam C Ou, Luis Andres Lesmes, Abigail H Christie, Renee A Denlar, and Karl G Csaky
To assess the effectiveness of an active learning approach to measuring the contrast sensitivity function (CSF) in patients with various degrees of dry age-related macular degeneration (AMD) under multiple luminance conditions.
Patients with AMD (26 intermediate AMD, 19 AMD with subretinal drusenoid deposits (SDD), 20 geographic atrophy (GA)) and 23 age-matched controls were tested with the Manifold Contrast Vision Meter (Adaptive Sensory Technology, San Diego, CA) and the qCSF algorithm, which applies active learning to estimate a model of the CSF's global shape. Testing was performed under conditions of standard and low luminance. For each AMD severity, the area under log CSF (AULCSF) and contrast sensitivities at individual spatial frequencies were calculated for analysis. Low luminance deficits (LLD) for visual acuity (VA) and AULCSF were calculated as the difference between standard and low luminance values. Results
Progressive decreases in AULCSF were observed as disease severity increased. For standard luminance, pairwise comparisons revealed significant differences between control/intermediate AMD (p<0.0005), control/SDD (p<0.0005), control/GA (p<0.0005), and intermediate AMD/GA (p <0.005). Similarly, for low luminance, pairwise comparisons revealed significant differences between the controls and each disease group (all p<0.0005), in addition to significant differences between intermediate AMD/SDD (p<0.005), and intermediate AMD/GA (p<0.005). No correlations were found between LLD VA and LLD AULCSF in any AMD groups.
Contrast sensitivity measured via qCSF under both standard and low luminance conditions correlates with advancing stages of dry AMD. The interaction between luminance and contrast sensitivity appears to reflect a different aspect of visual function than the interaction between luminance and VA.