Luminance changes of the fundus reflex

A recording retinoscope was developed to measure the luminance of the fundus reflex during problem-solving tasks. 10 students were used as subjects. The luminance of the reflex was recorded while the subjects read 5 passages of graded reading material and performed an addition task. A reversal design was used to determine the effects of pupil changes and accommodation on changes in the luminance of the reflex. Relatively large changes in the luminance of the reflex were recorded. These were due to accommodation. The subjects' comprehension of the reading material did not appear to affect the luminance of the reflex in the manner predicted by previous studies. However, a change in task from simple reading material to an addition task appeared to increase the luminance of the reflex.