An electrophysiological investigation of the macular photostress test.

The speed of macular recovery from photostress was measured as a function of age by subjective and objective techniques. The subjective procedures involved measuring the speed of recovery of habitual visual acuities after dazzling of the macula with a bright light. Macular function was assessed objectively by monitoring the development of the transient pattern VER after photostress. Both techniques indicated that the ability to recover from photostress decreased with age. However, the recovery of visual acuity and the restoration of baseline VER parameters had very different temporal characteristics. The time for restoration of baseline VER amplitude was usually several times longer than the time for subjective recovery of prestress visual acuity levels. Furthermore, subjects less than 30 years of age differed from the older group in that their recovery VER amplitudes tended to quickly surpass the baseline VER values, more so in the youngest age group. Most subjects over 30 did not show such super normal VERs and failed to recover baseline VEP amplitudes within 60 sec after photostress. These observations suggest age-related functional differences in retrobulbar components of the visual system.