Abstract
The effect of refraction accuracy on the differential light threshold of a Goldmann size III (0.43° diameter) stimulus was evaluated in the right eyes of five normal subjects with randomly ordered sequence of piano, +1.00-, +2.00-, +3.00-, +4.00-, +5.00-, and +6.00-diopter (D) spherical overcorrections. Threshold measurements were performed at 0°, 5°, 10°, 15°, 20°, and 25° eccentricity nasally along the 180° meridian with the F4 program on the Octopus 201 perimeter. The +1.00- through +6.00-D overcorrections decreased the threshold values by an average of 1.4, 2.9, 4.2, 5.6, 6.7, and 7.6 dB, respectively, compared with the piano overcorrection. The depression of the differential light threshold was of similar magnitude at all eccentricities within the central 25°.
