Normal Dark Adaptation Results for the Roland Consult Dark Adaptometer

Abstract

Purpose: : To develop a normative database for dark adaptation for the Roland Consult Dark Adaptometer.

Methods: : Two sets of dark adaptation tests were performed in 12 healthy individuals of 20-30 years of age. Each test was performed upon one eye at a time with intense white light bleaching for 6 minute prior to the test at 7000 candles/m². First test represented red flash stimulus (all stimuli were at 2° of visual angle) every second for 10 minute, aligned with the center of the eye, focused directly on the light stimulus. Second test consisted of green flash stimulus every second for 30 minute, with the eye focused 20° temporal to the light positioned directly in front of the eye. Dark adaptation functions were analyzed by plotting time on the x-axis against the log of light intensity on the y-axis. 10 minute and 30 minute were chosen as test times. Three data sets were obtained and analyzed: red stimulus for the cone receptors and green stimulus for cone and rod receptors.

Results: : The red stimulus test yielded data which was fitted with exponential decay curves for cone function, with horizontal asymptote at mean value (±StD) of -2.06 ± 0.234 log cd/m². Mean t-time constant of this curve was 35.0 ± 23.1 s. The green stimulus test yielded two exponential decay curves, one occurring during the first 10 minutes and the other in the 10 to 30 minute range, demonstrating the adaptation of cone and rod receptors, respectively. For the cone portion of the test, the horizontal asymptote had mean value of -1.22 ± 0.357 log cd/m² and average t-time constant of 15.3 ± 12.3 s. The rod portion had a mean horizontal asymptote of -3.31 ± 0.458 log cd/m² with mean time constant of 327 ± 110 s.

Conclusions: : Our data are being used to establish a normative database for dark adaptation. This database will be used to assess patients with impaired night vision. The study is ongoing and more data will be collected, and the database will be expanded to include patients from other age groups as well.

Keywords: photoreceptors: visual performance