The Effect of Age on the Temporal Summation of Achromatic Perimetric Stimuli.

Abstract

To examine the temporal summation of a Goldmann III-sized stimulus under the conditions of standard automated perimetry in healthy participants of varying age. Twenty-seven healthy individuals of varying age (24-80 years) were tested. Achromatic contrast thresholds were measured for seven 0.48° diameter (near Goldmann III) spot stimuli of varying presentation duration (1-24 frames, 1.8-191.9 ms) at 8.8° eccentricity in the visual field along the 45°, 135°, 225°, and 315° meridians. All stimuli were displayed on a CRT display with a background set to 10 cd/m2. Iterative two-phase regression analysis was used to estimate the critical duration from each localized temporal summation function. A significant decrease in contrast sensitivity for all stimulus durations examined in this study was observed with increasing age in both the superior and inferior hemifield (P < 0.001). Despite this, no significant change in the critical duration was observed as a function of age in either the superior (r² = 9.1 × 10⁻⁹, P = 0.99) or inferior hemifield (r² = 2.4 × 10⁻⁵, P = 0.98). Age-related changes in the visual system, although leading to a reduction in contrast sensitivity, are not accompanied by a change in temporal summation for a detection task with an achromatic 0.48° diameter spot stimulus. This is important to know when proceeding to examine temporal summation changes in diseases like glaucoma.