Pupil Dilatation after Single and Triple Doses of Mydriatic Agent in Preterm Infants
Achara Punyawattanaporn MD*, Supaporn Tengtrisorn MD*, Pasuree Sangsupawanich MD**
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand ** Department of Pediatrics, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
Objective : To compare the pupillary response to a single drop and three drops of a combination of eye drops
(0.2% cyclopentolate and 1.0% phenylephrine) in preterm infants.
Results : Prospective comparative study.
Material and Method: Preterm infants scheduled to undergo their first retinopathy of prematurity (ROP)
screening in the Neonatal Intensive Care Unit, Songklanagarind Hospital, between 1 August 2007 and 30
August 2008, were enrolled in the present study. An eyelid speculum was placed after the topical anesthetic,
0.5% tetracaine, application to measure the baseline horizontal pupil diameter with a Vernier caliper. Then
each eye was randomized to either receive a drop of mixture of 0.2% cyclopentolate and 1.0% phenylephrine
single dose for group A, or triple doses of 10-minute interval for group B. The pupil diameter was measured at
45 and 60 minutes after instillation and a fundus examination was performed afterward.
Results : Seventy preterm infants, 45 males and 25 females, were included in the present study. The mean
gestational age was 30.49 + 2.34 weeks (range of 24-36 weeks) and the mean birth weight was 1,368.00 +
438.99 grams (range of 640-2,850 grams). At baseline, the mean pupil diameter was 2.18 + 0.44 mm in group
A and 2.19 + 0.44 mm in group B (p = 0.90). The mean pupil diameter at 45 minutes after instillation was 5.50
+ 0.80 mm in group A and 6.02 + 0.56 mm in group B (p < 0.01). At 60 minutes after instillation, the mean pupil
diameter was 6.13 + 0.82 mm in group A and 6.77 + 0.41 mm in group B (p < 0.01).
Conclusion : The pupil size of preterm infants was significantly larger after three drops of the eye drop mixture
(0.2% cyclopentolate and 1.0% phenylephrine) than after a single drop. However, a dilated pupil diameter >
6 mm was adequate for the peripheral retina examination.
Keywords : Premature infant, Retinopathy of prematurity, ROP, Mydriatic
