Quantitative assessment of lateral interaction as determined by computerized quantitative layer-by-layer perimetry.

Abstract

Quantitative layer-by-layer perimetry is a psychophysical technique which assesses lateral interaction in human vision. In prior designs of this technique the test procedure was time-consuming and quantitative assessment of the results was not possible. In order to shorten test duration and provide quantitative experimental data, a new computerized version of the technique has recently been developed. A mathematical model for describing lateral interaction as assessed by computerized quantitative layer-by-layer perimetry was developed, and experimental data from the testing of 18 normal persons were fitted to the model. Two descriptive parameters of, respectively, lateral stimulation and lateral inhibition were for each test point related to the differential light sensitivity and to the eccentricity in the visual field. The two parameters describing lateral stimulation could not be reliably estimated. However, the two parameters describing lateral inhibition showed, respectively, a positive correlation with the differential light sensitivity in the visual field and a significant decline with increasing eccentricity in the visual field. The technique and the mathematical model employed are suitable for quantitative assessment of lateral inhibition in human vision.