The Alteration in Static Perimetry Thresholds Caused by the Prismatic Effect of Ophthalmic Lenses

Abstract

Contrast sensitivity for target I (3.24/diameter) of the 30 cm radius Goldmann perimeter was measured along the horizontal meridian to 50 degrees eccentricity in 5 subjects. Background luminance was 10.0 cd/m2 and stimulus duration was 130±4 ms. Using this data and the ophthalmic lens prismatic effects to be presented in another paper, the alteration in static perimetric sensitivity caused by spectacle lens prismatic effects was estimated. For spectacle lenses with powers between -6 D and + 10 D, the maximum sensitivity alteration was only 0.30 log units (+10 D, 25 degrees temporal) for a 14 mm vertex distance. As the experiment used conditions producing maximum visual field sensitivity gradients, and hence the maximum alteration in sensitivity caused by prismatic effects, prismatic effects of corrective ophthalmic lenses can be ignored within the central 30 degrees - 40 degrees visual field during static perimetry for lens powers less than ± 10 D.