A recent study published in the
journal JAMA Ophthalmology found that substituting micro drops with standard
drops was non-inferior as it reduced the systemic effects in preterm infants
who have retinopathy of prematurity.

Retinopathy of prematurity (ROP)
is one of the most significant risk factors in premature infants who are born
prematurely as it can affect vision. Eyedrops that contain either adrenergic
agonists, muscarinic antagonists, or their combination are used for adequate
pupil dilation. However, they have the risk of causing systemic cardiorespiratory
and gastrointestinal adverse events. Hence, researchers conducted a study to
examine the noninferiority of micro drops of a combined mixture of 1.67%
phenylephrine and 0.33% tropicamide compared to the standard eye drops.

A randomized,
double-masked, noninferiority, crossover design trial was conducted on
premature infants undergoing ROP screening at a tertiary center in Northern
Greece from September 2021 to January 2023. Infants with gestational age below
32 weeks and/or birthweight under 1501 g or infants beyond these thresholds
referred by an attending neonatologist due to comorbidities were considered
eligible for the study. Random allocation was done to prescribe micro drops or
standard drops of the diluted mixture with a 1-week washout period.Also Read: New Eye Drop Therapy For Dry Age Related Macular Degeneration: Study Finds

The horizontal pupil diameter at
45, 90, and 120 minutes was measured using a customized ruler in 0.5-mm
increments. A predefined noninferiority margin of −0.4 mm was set. Parameters
like heart rate, oxygen saturation, blood pressure measurements at 45, 90, and
120 minutes, 24-hour hypertensive episodes, and 48-hour systemic adverse events
were assessed. Hydrophilic liquid chromatography-tandem mass spectrometry measured
Phenylephrine concentration in peripheral blood within 3 hours post-instillation.

Findings:

About 83 infants were randomized with a mean
[SD] gestational age of 29.7 [2.0] weeks and a mean [SD] birth weight of 1277
[374] g). Micro drops were superior for mydriatic efficacy
at 45 minutes and non-inferior at 90 and 120 minutes. After standard drops, lower oxygen saturation
levels at 45 and 90 minutes and a higher percentage of 24-hour hypertensive
episodes were observed. A 1-compartment model with first-order
absorption best described the pharmacokinetic data.Also Read: Perfluorohexyloctane Eyedrops safe for contact lens wearers and may reduce contact lens dropout: Study

Thus, the researchers concluded
that micro drops of combined 1.67% phenylephrine and 0.33% tropicamide in a
mixture were proven superior regarding mydriatic efficacy at 45 minutes and
non-inferior at 90 and 120 minutes compared with standard drops of the same
regimen administered in infants undergoing ROP screening.

Micro drops were found to be
safe, non-inferior to standard drops, and reduce system absorption. Due to
their diagnostic efficacy, they can be preferable for ophthalmologists and
neonatologists.

Further reading: Seliniotaki AK, Lithoxopoulou
M, Virgiliou C, et al. Efficacy and Safety of Mydriatic Microdrops for
Retinopathy of Prematurity Screening: The MyMiROPS Randomized Clinical
Trial. JAMA Ophthalmol. Published online December 26, 2024.
doi:10.1001/jamaophthalmol.2024.5462