Mobility Performance in Retinitis Pigmentosa Under Different Lighting Simulation Conditions

This study examined the mobility performance in retinitis pigmentosa (RP) under different simulation lighting conditions. A total of twenty-one subjects with RP and twenty-one age-matched controls were enrolled. Preferred Walking Speed (PWS) were determined using a simple mobility course at 61 cd/m2 while Percentage of Preferred Walking Speed (PPWS) and error score were determined at five different illumination level which were 62, 47, 20, 6 and 1 cd/m2 using a complex mobility course. RP and normal people had similar mobility performances in simple mobility situations at a constant high light level. In lower light levels as well as in complex mobility situations, RP subjects demonstrated markedly reduced mobility performance. The relationship between PPWS and luminance was linear, with the PPWS decreasing significantly when the mobility course luminance dropped below the illumination of 20 cd/m2 . The Error score was also noted to be linearly related to log luminance. A luminance level of 20 cd/m2 may provide a useful decision point in setting indoor light levels for clinical mobility courses.