Reaction time in automated kinetic perimetry: effects of stimulus luminance, eccentricity, and movement direction

Purpose: To determine the effects of stimulus eccentricity and luminance le vel on the reaction time (RT) of young normal volunteers during automated k inetic campimetry. Methods: We used a specially designed video-campimetric device equipped with a continuous infrared (IR) pupillographic fixation con trol (Tubingen Computer Campimeter) and recorded reaction times upon presen ting horizontally moving small circular stimuli (size 26'; constant angular velocity 2 degrees /s) starting at 16 locations within the central 30 degr ees -radius of the visual field. Two different levels of stimulus luminance were used (41.6 cd/m(2) and 110 cd/m(2)), while background luminance was 1 0 cd/m(2). Each stimulus was presented a total of six times in a randomized order. Subjects were 12 healthy young individuals (aged 21-30 years) with normal ophthalmic examinations. An analysis of variance (ANOVA) was perform ed on the data. Results: RTs showed considerable inter- and intra-individua l variation with individual least squares means (LSM, fitted values of a li near model) ranging from 305 to 454 ms, and residual standard deviation (R. S.D.) 66 ms. Reaction times did not differ significantly as a function of s timulus direction (P > 0.6). Higher luminance levels produced significantly reduced reaction times for all stimulus locations and directions (mean red uction: 16 ms; P<0.0001). Reaction times increased with increasing eccentri city, in the mean by 1.8 ms per degree of visual angle, from 365 +/- 4 ms ( S.E.M.) foveally, to 407 +/- 2 ms at 30<degrees> eccentricity; (P<0.0001). Conclusions: Automated kinetic perimetry should be designed to cope with si gnificant, variable interindividual response characteristics. Other stimulu s related factors, such as eccentricity or luminance level, have a signific ant but comparatively small effect on reaction time within the central 30<d egrees>-radius visual field in healthy young individuals. (C) 2001 Elsevier Science Ltd. All rights reserved.