The Effect of Eyedrop Size on Pupillary Dilation Using the Nanodropper Bottle Adapter

Audrey Chow,1 Jin Choi,1 Jason Bacharach1,2 1Department of Ophthalmology, California Pacific Medical Center, San Francisco, CA, USA; 2North Bay Eye Associates, Petaluma, CA, USACorrespondence: Jin Choi, Department of Ophthalmology, California Pacific Medical Center, 711 Van Ness Ave, Suite 250, San Francisco, CA, 94102, USA, Email [email protected]: Ophthalmic medications administered via standardized eyedrop bottles have an average drop size of 40 μL, but absorption is limited to the conjunctival sac volume of 7– 10 μL. The Nanodropper is a commercially available eyedrop bottle adapter capable of consistently delivering 10 μL aliquots. We hypothesized that the Nanodropper would supply a sufficient medication dose for mydriasis that is non-inferior to the standard eyedrop bottle.Material and methods: Adult patients scheduled for routine bilateral eye dilation were selected. Exclusion criteria included anisocoria, use of mydriatic agents, and unilateral pseudoexfoliation. One eye was randomly selected and dilated with the Nanodropper, and the fellow eye dilated with the standard bottle with a 50/50 mixture of 1% tropicamide and 2.5% phenylephrine. Pre- and post-dilation pupil sizes were objectively measured with a pupillometer and compared between fellow eyes with a noninferiority margin of 0.5mm.Results: A total of 54 patients (108 eyes, 54 pairs) were included in the study. Pre-dilation pupil sizes were similar in the Nanodropper eye compared to the fellow eye. There was no difference in post-dilation pupil size between fellow eyes with a noninferiority margin of 0.5mm (95% CI [− 0.09, 0.15], p = 0.67).Discussion: This study demonstrates that small volume eye drops using the Nanodropper adapter are as efficacious as standard volume drops for mydriasis. This may provide many clinical, practical, and economic advantages such as reducing medication excess, toxicity, and material costs.Conclusion: The Nanodropper is non-inferior to the standard eyedrop bottle for pupillary dilation. Small volume eyedrops may reduce medication waste and side effects and improve affordability and patient compliance.Plain Language Summary: Efficacy of small volume drops using a Nanodropper adapter for pupil dilation compared to a standard volume was studied. The Nanodropper mechanism was non-inferior to standard volume drops for mydriasis.Keywords: medications, mydriatics