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

PurposeTo compare the mydriatic efficacy of different numbers of eye drops for retinal examination of premature infants.MethodsThis 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.ResultsA 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.ConclusionsEffective 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.