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James C Liu, Wesley Green, Susan M Culican, Gregory Van Stavern; Assessing the utility of phenylephrine 2.5% for diagnostic pupillary dilation. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5538.
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© ARVO (1962-2015); The Authors (2016-present)
Phenylephrine eye drops are routinely used in dilated eye examinations, but have increased drastically in price over the past few years. We performed a prospective, unmasked, crossover pilot study to evaluate whether the addition of phenylephrine to tropicamide produces any statistically and clinically significant change in pupil size.
Twenty healthy students and faculty members affiliated with the Washington University School of Medicine were enrolled. Each had 3 distinct dilating eye drop regimens administered to the left eye on separate days. The routine regimen used clinically at Washington University for dilated eye examination is tropicamide (T) + proparacaine (PP) + phenylephrine (PE) (T+PP+PE). This was considered the standard therapy to which tropicamide + proparacaine (T+PP) and tropicamide alone (T alone) were compared. Measurements of pupil size were made before and 30 minutes after eye drop administration using an automated pupillometer. Primary outcome measures were post-dilation pupil size and proportion of pupils able to achieve post-dilation pupil size >7mm. The latter served as a measure of clinical significance. Comparisons between the 3 regimens were made using paired t-tests and McNemar’s test, with T+PP+PE serving as the standard therapy.
Mean post-dilation pupil size was 7.94±0.78mm, 7.64±0.78mm, and 7.48±0.77mm for T+PP+PE, T+PP, and T alone, respectively. T+PP+PE was statistically superior to T+PP (p=0.0043) and T alone (p<0.0001) with respect to post-dilation pupil size. The proportion of pupils able to achieve adequate pupil dilation of >7mm was 90%, 80%, and 70% for T+PP+PE, T+PP, and T alone, respectively. No statistical difference was observed in each regimen’s ability to achieve adequate pupil dilation of >7mm (T+PP+PE and T+PP: p=0.47; T+PP+PE and T alone: p=0.13).
The addition of phenylephrine eye drops to tropicamide provides larger pupil dilation, but the magnitude of benefit is marginal and clinically insignificant in this healthy cohort.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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