A randomized controlled trial to determine the lowest effective dose for adequate mydriasis in premature infants

Abstract

Purpose: To compare the mydriatic efficacy of different numbers of eye drops for retinal examination of premature infants.

Methods: This pilot study enrolled preterm infants born at <32 weeks' gestational age who were scheduled for retinopathy of prematurity screening examinations. In all study group assignments, the right (treatment reference group) eye received 3 eye drops per current neonatal intensive care unit protocol, whereas the left (test) eye was randomized at each examination to receive either: 0, 1, or 2 drops. Pupils were dilated with the use of a cyclopentolate 0.2% and phenylephrine 1% ophthalmic solution. Pupil size (in mm) was measured by a single examiner at 0 (baseline), 45, 90, and 120 minutes after instillation. Retinal examination occurred at the first opportunity to adequately visualize the peripheral retina. Comparison of the means was calculated using paired t test, t test, or analysis of variance, as appropriate.

Results: A total of 64 eye examinations were performed on 15 enrolled infants (mean gestational age, 28.7 ± 2.6 weeks, 53% white; 40% male). No significant differences existed in mean pupil size between the 1-, 2- and 3-drop groups at baseline, 90 minutes, and 120 minutes. All 1-drop group eyes could be examined by 90 minutes. The 0-drop group maintained baseline size.

Conclusions: Effective mydriasis was achieved in the test eye with 1 or 2 drops and was sustained to 120 minutes. Therefore, retinal examinations could be completed by 90 minutes in most infants with the use of 1 drop. A larger study is needed to determine the effect of iris color and severity of ROP on these findings.