Low luminance deficit and night vision symptoms in intermediate age-related macular degeneration

Background/aims To determine the relationship between self-reported visual difficulties under low luminance conditions (night vision symptoms) and visual function measures in intermediate age-related macular degeneration (AMD). Methods One hundred participants with bilateral intermediate AMD were examined in a prospective cross-sectional study with visual function measures including best-corrected visual acuity (BCVA), low luminance visual acuity (LLVA) and microperimetry in both eyes. A 10-item Night Vision Questionnaire (NVQ-10) was then used to determine the degree of self-reported night vision symptoms experienced by each participant. For analyses, low luminance deficit (LLD) was derived as the difference between LLVA and BCVA, and microperimetric mean sensitivity (MS; all points) and central sensitivity (CS; points within the central 1 degrees) were determined. Rasch analysis was used to estimate the person measure of night vision symptoms, and its relationship with visual function parameters was determined. Results NVQ-10 person measures were significantly associated with LLD (beta coefficient 0.067, 95% CI 0.005 to 0.130, p=0.034), but not BCVA, LLVA, microperimetric MS or CS (p=0.090). Participants with the highest degree of self-reported night vision symptoms (fourth quartile of person measure) had significantly worse LLD than those with the least difficulty (first quartile of person measure; p=0.019). Conclusions In individuals with bilateral intermediate AMD, LLD was associated with self-reported night vision symptoms, suggesting that this measure may better capture the visual difficulties experienced by these individuals under low luminance conditions than the conventional measure of photopic visual acuity.