The pupil cycle time test: Its diagnostic value and limitations in the diagnosis of unilateral optic neuropathy

Abstract

The authors report a simplified method for the clinical application and interpretation of the pupil cycle time test (PCT-test time) in the diagnosis of uniocular optic neuropathies. It is shown that normal interocular differences of ten pupil cycles are less than 0.2 sec at a 99% confidence level, such interocular differences being a gaussian age-independent parameter. Deep uniocular amblyopia as well as unilateral retinal disease which affect the whole extension of the posterior pole of the eye or more, significantly influence the interocular differences of the PCT-test time. Unilateral cataracts do not influence this if a regular pupil cycling response can be elicited in the eye with the lens opacity. If retinal disease or previous amblyopia have been ruled out both in the suspected and in the normal eye, the finding of an interocular difference in the PCT-test time more than 0.2 sec for ten pupil cycles or an insufficient pupil cycling to edge-light pupil stimulation will strongly support the clinical diagnosis of optic neuropathy in the eye with longer or hyporeactive pupil cycling response.

Key Words:

• optic neuropathy
• retinal disease
• amblyopia
• cataracts
• pupil light response
• pupil cycle test