The effect of cycloplegia on the visual contrast sensitivity function

Contrast sensitivity assessment is one of several emergent techniques being considered for inclusion in a visual standards test battery for the Army, particularly for the evaluation of Army aviators. Since a cycloplegic refraction is required for initial selection of candidates for Class I and Class IA flying duty, it is important to determine what effect, if any, cycloplegia has on the contrast sensitivity function. There were 12 subjects tested, all officers in preparation for flight training who had passed a recent Class I flight physical. Contrast sensitivity functions were obtained under normal ambient conditions and in the presence of a glare source both under manifest and cycloplegic conditions. Cycloplegia produced a small reduction in contrast sensitivity under normal ambient conditions, and a greater reduction under glare conditions. For both conditions, the cycloplegia effect was greater for the higher spatial frequency gratings than for the lower.