A Randomized Controlled Trial to Determine the Lowest Effective Dose for Adequate Mydriasis in Premature Infants

Premature infants need to have eye exams starting at about 4 weeks of age and continuing until their retinas (membrane at the back of the eye which collects and transfers light) is fully grown. These exams are done to see if they have developed ROP, a disease which can lead to blindness if not treated.

The ophthalmologist (eye doctor) looks through the enlarged pupil (opening at the front of the eye) to see the retina. The drug that is used to dilate the pupil, Cyclomydril, has been shown to have side effects in premature infants. No literature has shown what the optimal dose is for premature babies. Nursery policy is to give 3 drops of Cyclomydril in each eye, at 5 minute intervals, 45-60 minutes before a scheduled eye exam. We sought to reduce the dose without delaying the exam for an under-sized pupil.

In the study, each infant is randomized at the time of the exam to receive either 0, 1 or 2 drops of Cyclomydril in the left eye and 3 drops in the right eye to serve as their own control. The zero-drop group was created to test the contralateral (opposite eye) effect of 3 drops in the right eye. Pupil dilation size is measured using the Colvard pupillometer by a Pediatric Ophthalmologist examiner (G.V.V.) who was not masked to study group assignment.

Measures of pupil size are done at baseline (before any drops given), 45, 90 and 120 minutes after the first drop was given. ROP screening exam is done at the first opportunity to visualize the posterior and peripheral retina.

Additional drops are given at 120 minutes if the observer is unable to complete the exam prior to that point.