Comparison of the human electro-oculographic response to green and near-ultraviolet stimuli

We recorded the electro-oculogram from 27 normal subjects by means of green and near-ultraviolet (UVA) stimulation. After a 40-minute dark-adaptation period, baseline responses were recorded. In response to the green stimulus, the electro-oculogram increased from this level by an average (+/- standard error of the mean) of 49.5% +/- 4.0%. Although the predicted scotopic effectiveness of the ultraviolet stimulus was more than 3 log units below that of the green stimulus, the near-ultraviolet-induced electro-oculogram increased to an average of 21.9% +/- 3.0% above baseline. This response cannot be due to lens fluorescence to the near-ultraviolet stimulus, since two aphakic subjects had electro-oculographic responses of 32% and 76% above baseline to near-ultraviolet stimuli. Neither the green nor the ultraviolet electro-oculogram changed significantly with age. These large responses to near-ultraviolet stimulation demonstrate the need for standardizing light sources for electro-oculographic testing because the degree of near-ultraviolet irradiance varies considerably according to their design characteristics.