Comparison of the Effectiveness of Mydriasis by Two Instillation Methods of Combined 0.75% Tropicamide and 2.5% Phenylephrine Eye Drop in Preterm Infants
Pittaya Phamonvaechavan MD*, Kanya Chutasmit BS, MNS**, Parichat Damrongrak BNS, MNS**, Supanna Koukiatkul BNS**, Tassanee Wongkiatkajorn BNS**, Sopapan Ngerncham MD**
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand ** Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To compare the effectiveness and safety of two instillation methods of combined 0.75% tropicamide and 2.5%
phenylephrine at 0, 5 minutes (min) with the same combined regimen at 0,30 minutes in preterm infants.
Material and Method: A prospective, cross-over, randomized controlled trial was performed to compare 0, 5-min instillation
(Method A) of combined 0.75% tropicamide and 2.5% phenylephrine with 0, 30-min instillation (Method B) of the same
regimen. Forty-two preterm infants scheduled for screening retinopathy of prematurity (ROP) were randomly assigned to two
groups. Group 1 was defined as preterms applied by Method A at first examination then by Method B 1-4 weeks apart whereas
vice versa in Group 2. Pupil size, heart rate (HR), systolic and diastolic blood pressure (SBP, DBP) were recorded before and
after eye-drop instillation.
Results : Mean time to 7-mm pupil size was no statistically significant difference between the two methods (Method A 46.47
min, Method B 46.58 min; p = 0.894). Method B has mean longer time to maintain 7-mm pupil size than Method A (Method
A 67.67 min, Method B 75.33 min); but not statistically significant different (p = 0.323). HR, SBP and DBP were not significant
change between the two methods.
Conclusion : Both instillation methods produced consistently sufficient mydriasis and safety for evaluation peripheral fundus.
Method B has slight longer mydriatic effect than Method A; thus giving more time to evaluate infant’s eye for ophthalmologists.
Keywords : Mydriasis, Pupillary dilation, Tropicamide, Phenylephrine, Retinopathy of prematurity (ROP), Preterm infants
