P Fosse¹, A Valberg²
¹Tambartun National Resource Centre of the Visually Impaired, Vision and Light Laboratory, Melhus, Norway; ²Norwegian University of Science and Technology, Department of Physics, Section of Biophysics, Trondheim, Norway
Purpose: To study the effects of luminance on visual acuity and reading performance in 13 subjects with age-related macular degeneration (AMD).Method: Oral reading speed and letter visual acuity were measured at luminance levels ranging from 4 to 1200 cd/m². Reading performance at different light levels was compared with self-reports of lighting comfort. Results: For six subjects, changing the light level affected acuity and reading in much the same way, with a Spearman correlation coefficient ranging from 0.69 to 0.95. For the seven remaining subjects, effects of luminance on acuity correlated weakly with lighting needs during reading. Only self-reports could identify the optimal luminance levels for which maximum reading speed was normally obtained. Conclusion: Among subjects with AMD, the effect of luminance on visual acuity cannot reliably predict lighting needs during reading. In order to reveal the best functional luminance range, a combination of objective measurement of reading speed with self-report seem necessary and adequate.
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