An application of threshold-versus-intensity functions in automated static perimetry

Increment thresholds were measured over a range of adapting illuminances using a modified automated static perimeter. The data were fitted to a threshold versus intensity model (log T = log T0 + log ((A + A0)/A0)n) and the values log T0 and log A0 estimated. The effect of eccentricity and age on log T0 and log A0 was examined in normal subjects. A small group of patients with ocular disease were then assessed. Macular degeneration appeared to act as disease processes acting near the photoreceptor (d1 model). Glaucoma seemed to act near the site of retinal gain (d3 model). This analysis method may be of value in developing light adaptation strategies in people with ocular disease.