Purpose: To evaluate whether the standard dilating drop regimen consisting of phenylephrine, tropicamide, and proparacaine produces clinically significant improvement in pupil size compared to tropicamide and proparacaine during diagnostic eye examination. Methods: Sixty-three adult patients at Washington University School of Medicine Eye Clinic were enrolled in this prospective, randomized trial. Each patient received one of two dilating drop regimens: phenylephrine + tropicamide + proparacaine (PE+T+PP), which is considered the standard therapy, or tropicamide + proparacaine (T+PP). Main outcome measures were the proportion of pupils able to achieve successful clinical examination without need for additional dilating drops and change in predilation to postdilation pupil size. Comparisons were made using McNemar's test, repeated measures analysis of variance, and Fisher's test to determine whether PE is a necessary component of the standard eye examination. Results: There were no statistically significant differences between the PE+T+PP and T+PE treatment groups in predilation to postdilation changes in average resting pupil size (1.58 ± 0.66 and 2.61 ± 0.79; P = 0.57) or constricted pupil size (2.52 ± 0.93 and 3.56 ± 0.96; P = 0.15). There was no statistically significant difference between patients who obtained a successful dilated pupil examination between those receiving PE+T+PP and those receiving T+PP as determined by the examining physicians (Fisher's, P = 0.67). Conclusion: The addition of phenylephrine to tropicamide and proparacaine did not improve pupillary dilation size or ability to conduct a clinical examination. A single dilating agent using tropicamide should be considered in clinical practice.
Keywords: clinical utility; dilating agent; eye examination; phenylephrine; tropicamide.