The
mydriatic effects of
ibopamine solution at the concentrations of 0.25%, 0.50%, 1% and
tropicamide solution at the concentration of 1% were evaluated in 22 clinically healthy volunteers. The study was conducted at single dose, instilling 1 drop of each concentration of
ibopamine and of
tropicamide in one eye and 1 drop of placebo in the other. The pupillary diameter was measured by photographic pupillography immediately before and
at 10, 20, 30, 45, 60, 90, 120, 180, 240 min after each instillation. Immediately before and 45 min after each instillation, visual acuity was also measured for both near and distant objects. The
ibopamine solution exerted a dose-related
mydriatic effect in both magnitude and duration. The mean maximum pupillary diameters were 5.5, 8.0, 9.1 mm with
ibopamine at 0.25%, 0.50%, 1% and 8.6 mm with
tropicamide. The mean times to reach the maximum pupillary diameter were 60, 54, and 50 min with the three concentrations of
ibopamine, and 47 min with
tropicamide. The duration of the
mydriatic effect was less than 4 h with
ibopamine and very much more with
tropicamide. No effect on accommodation was found with
ibopamine, while a
cycloplegic effect was constantly noted with
tropicamide. On the basis of the results obtained, it is concluded that
ibopamine is to be preferred when
mydriasis is required with good absolute values and brief duration (examinations of the fundus, examinations with Goldmann's lens, etc.), without cycloplegia.