1 Tambartun National Resource Centre for the Visually Impaired, 
N-7224 Melhus,
² Dept. of Physics, Section of Biophysics,
Norwegian University of Science and Technology, N-7491 Trondheim,
Norway.

Purpose:

To establish the relationship between oral reading rate and lighting needs for persons with age-related macular degeneration (AMD).

Method:

13 visually impaired subjects with AMD (and no additional eye disorder) participated in the study. Three persons with normal vision served as controls. Prior to the reading rate assessments, acuity and magnification needs were established for all clients. Reading speed of printed text was measured at luminance levels ranging from 4 to 1200 cd/m². These objective measures were compared with self reports.

Results:

Maximum reading speed was obtained for a luminance between 100 and 400 cd/m² for seven subjects, and between 600 and 1 200 cd/m² for the remaining six subjects. However, for 7 subjects satisfactory and comfortable reading was achieved for a three-octave luminance range or larger, whereas five subjects accepted only a narrower luminance range. Self reports agreed well with objective measurements, and, in spite of fluent reading, for five clients they helped identify uncomfortably low and high light levels. For subjects with normal vision, reading rate did not change significantly as a function of photopic luminance.

Even if it is of interest to find the optimal and functional range of illuminance for reading, from a rehabilitation point of view it is equally important to identify preferences and subjective constraints. In our cases subjective evaluations were precise enough to replace objective measurements. Supported by grants from

The Norwegian Association of the Blind and Partially Sighted, and

Thonning Owesen’s Foundation.