Comparison of Two Fast Quantitative Methods for Evaluating the Stiles‐Crawford Function

Stiles‐Crawford (SCE) functions are determined using an increment threshold procedure. The customary technique requires considerable time to obtain a full SCE function and in many situations, both clinical and experimental, it is imperative that the SCE function be evaluated at many retinal loci in as short a time as possible. We have been using two different variants of the standard method, one requiring a very limited number of threshold settings at five fixed entry points in the entrance pupil (5‐point method) and in the other, thresholds are determined at only three preselected entry points (3‐point method). The time required to obtain a complete SCE function is of the order of 5 to 8 min using either method. Comparison and statistical evaluation of the techniques are presented.