Visual complaints of patients with glaucoma and controls under optimal and extreme luminance conditions.

PURPOSE: To determine (i) whether, compared to controls, visual complaints of glaucoma patients are more pronounced under extreme luminance conditions than in the optimal luminance condition and (ii) whether complaints belonging to different extreme luminance conditions are associated.
METHODS: We developed a luminance-specific questionnaire and sent it to 221 glaucoma patients (response rate 81%); controls (182) were primarily their spouses. Median (interquartile range) mean deviation of the visual field of the patients' better eye was -4.5 (-10.7 to -1.9) dB. Questions were addressing visual performance under five luminance conditions: presumed optimal (outdoor on a cloudy day), low, high, sudden decrease and sudden increase. We compared percentages of patients and controls who reported visual complaints while performing activities under different luminance conditions.
RESULTS: Percentages of patients and controls with visual complaints were 4 versus 0% (p = 0.02) for optimal luminance and 48 versus 6% (p < 0.001), 22 versus 1% (p < 0.001), 32 versus 1% (p < 0.001) and 25 versus 3% (p < 0.001) for low, high, sudden decrease and sudden increase in luminance. Within the group of glaucoma patients, the frequency of complaints increased significantly with increasing disease severity at a Bonferroni-corrected p value of 0.003 for all but one (p = 0.005) luminance-specific questions that addressed extreme luminance conditions.
CONCLUSION: The concept of (early stage) glaucoma as an asymptomatic disease is only valid with optimal luminance. Differences in visual complaints between glaucoma patients and controls are greater under extreme luminance conditions, especially in the dark. The fact that the cases were aware of their diagnosis could have induced bias.