Minimizing risk of adverse reactions to mydriatic agents in binocular indirect ophthalmoscopy.

To minimize the risk of adverse side effects from mydriatics during binocular indirect ophthalmoscopy, a procedure was developed which intentionally starts with a dose significantly less than an ED99. Using a clinically effective diameter of greater than 7 mm as a criterion, I found that 1 drop of 0.5% tropicamide (T) constituted an ED74 (N = 46). When 1 drop of 2.5% phenylephrine (P) was added, this increased to an ED93 (N = 27). If present results can be generalized, then 1 drop of T, supplemented at 30 minutes with 1 drop of P, if necessary, should produce satisfactory dilatation in approximately 90% of the subjects.