Effect of Different Mydriatic Regimens Used for Pupil Dilation on the Vital Signs of Premature Infants for Retinopathy of Prematurity Screening in a Philippine Tertiary Hospital: A Randomized Double-Blind Clinical Trial

Abstract

Objectives. To determine the safety and efficacy of three different mydriatic regimens in premature infants referred for retinopathy of prematurity (ROP) screening using (1) multiple alternate instillations of 0.5% cyclopentolate hydrochloride and 2.5% phenylephrine (MAI), (2) single instillation of 0.5%/0.5% tropicamide + phenylephrine (SI) and (3) single instillation of 0.5%/0.5% tropicamide + phenylephrine with a cotton wick placed in the inferior fornix (SIW) in a Philippine tertiary hospital.

Methods. A randomized, double-blind, clinical trial included preterm infants for ROP screening at a Philippine tertiary hospital. After instillations via MAI, SI, and SIW, systolic blood pressure (SBP), diastolic pressure (DBP), mean arterial pressure (MAP), heart rate, and oxygen saturation were monitored. Pupillary dilation was also measured.

Results. Sixty preterm infants, 20 to each intervention, were included. The MAI group did not have significant changes relative to its baseline vital signs. The use of SI produced lower DBP (p<0.0106) and MAP (p<0.0027) compared to MAI. The use of SI produced lower DBP (p<0.01) and MAP (p<0.003) compared to MAI. The SIW group exhibited significant increases in SBP (p<0.002) and in MAP (p<0.04) compared to MAI. This increase in SBP exceeded the clinical normal values for <37 weeks old infants. Pupillary dilation did not have significant differences among groups (p=0.24).

Conclusion. Due to significant increase in SBP, it is recommended to discontinue SIW in preterm infants for ROP screening since it may promote the mydriatic’s systemic absorption. Except for the clinically increased heart rate in infants aged ≥37 weeks at examination, SI was found to be at par with the recommendation of the UK ROP Guidelines of May 2008.