The Paredrine test in normal eyes. A controlled study.

Paredrine has been used as an adjunct to the cocaine test for Horner's syndrome; however, there are no controlled studies measuring pupillary responses in normal eyes. Twenty-five volunteers with normal eye examinations received 1% Paredrine in one eye, followed by serial photography to document the extent of pupillary dilation. Pupillary measurements were taken from the photographs to prevent identification of the patient, control or treated eye, or the time after instillation of the eye drops. Lighter irides dilated more rapidly, and some patients with dark irides showed little response. The control eye showed progressive pupillary constriction as its fellow eye became more dilated.