Mydriatic solution for outpatient indirect ophthalmoscopy

A mydriatic used for outpatient indirect ophthalmoscopy should produce prompt, maximal, transient mydrasis after a single instillation. Cycloplegia or systemic side effects should be minimal. A solution of tropicamide with phenylephrine hydrochloride seems to achieve this most effectively. In a general retina clinic population, the percentage of pupils dilated, the degree of dilation, and the resistence of the dilation to intense illumination were used to evaluate various concentrations of the drugs. Eight-tenths percent tropicamide with 5% phenylephrine adequately dilated 98.8% of the eyes, among which 25% had dark irides and 9% were receiving miotic therapy. Reduction of the concentration of either component produced less adequate mydriasis; an increase of the tropicamide concentration resulted in a saturated solution with drug precipitate forming on storage and a less adequate dilation. With the optimal combination, 1 drop adequately dilates the general population; 2 drops appear on more effective than 1.