Iris pigmentation and susceptibility to noise-induced hearing loss.

The purpose of this retrospective study is to examine the possible association between iris pigmentation and susceptibility to noise-induced hearing loss in 2407 noise-exposed workers. The workers were between 16 to 65 years of age and were exposed to 2 to 42 years of work-related noise. Results demonstrated that dark-eyed workers presented a greater percentage of normal pure-tone thresholds than fair-eyed workers. Fair-eyed workers had threshold averages of 25.1 dB (right ear) and 26.0 dB (left ear) at 3, 4, and 6 kHz, which were significantly worse than workers with dark irises, with threshold averages of 15.8 dB and 17.2 dB in the right and left ear, respectively (p<0.01). Fair-eyed workers with less than 10 years of noise exposure had the same audiometric pattern as the dark-eyed workers exposed for more than 10 years. Workers not exposed to noise did not present significant differences in their audiometric pattern as a function of eye colour. These results suggest that iris pigmentation may be an additional indication of susceptibility to noise-induced hearing loss.