DIMENSIONS OF APPARENT PUPIL WHEN VIEWED AT OBLIQUE ANGLES

Correction factors are provided to estimate the reduction in retinal illumination level produced by the reduction in apparent pupil area when the eye is viewed at oblique angles. For each of the four experimental conditions investigated here, a correction of less than 0.1 log unit was found for 30 °n θ 30 °t. The present findings indicate that it is relatively inaccurate to use the cos-θ curve to predict the apparent pupil's H V ratio under conditions which approximate those studied here. Present findings also show that the use of 1% pilocarpine did not produce as small a pupil as did the use of the natural pupil viewing a 1,254 foot-candle visual field. The use of 1% Cyclogyl hydrochloride produced larger pupillary areas than did the natural pupil adapted to total darkness. The use of either drug did not ensure complete constancy of the pupil's size or shape. © 1969.