Tropicamide-induced mydriasis in densely pigmented eyes.

Clinically effective diameters (CED's) corresponding to illumination intensities used in direct ophthalmoscopy were determined in 30 young adults with densely pigmented irides after instillation of 1 drop of 0.5% tropicamide. All subjects were of Asian, Pacific Island, or Hispanic origin. The maximum CED was attained by 30 min and was maintained without significant change for the next 60 min. Ninety percent of the subjects had maximum CED's of 6.0 mm or more, and 57% had CED's of 7.0 mm or more. These figures correspond to the entrance pupil diameters and are free from the effects of corneal magnification. The average CED's for these densely pigmented eyes did not differ in a statistically significant manner from corresponding mean CED's for 97 less densely pigmented Caucasian eyes during the interval of 30 to 90 min after instillation of tropicamide. Tropicamide at 0.5% concentration appears to be an effective mydriatic for use in these densely pigmented eyes with procedures requiring intensities of illumination similar to those used in direct ophthalmoscopy.