Small Eye Drop Adapter May Reduce Medical Waste and Toxicity

A small volume eye drop adapter, which elutes 10.4 µL of medication, may decrease waste and medication toxicity while maintaining similar efficacy to standard of care drops eluting 50 µL of medication, according to a study published in Ophthalmology. However, the adapter failed to meet strict non-inferiority criteria for cycloplegia and constriction percentage. 

Researchers included 50 children (mean age, 9.3 years; 58% boys) in a prospective clinical trial and randomized 1 eye to mydriatic instillation with a 10.4 µL small eye drop adapter while the contralateral eye received the 50 µL standard of care. A single drop of 1% cyclopentolate, 1% tropicamide, and 2.5% phenylephrine were used for dilation.

All participants underwent refraction and pupillometry at baseline and 30 minutes post-dilation. A non-inferiority analysis was used to assess change in refraction, pupil constriction percentage and maximum pupil diameter after dilation.

The post-dilation spherical equivalent was 0.05 diopters (D) greater (95% CI, -0.28-0.37) in eyes receiving drops with the small eye drop adapter compared with the standard of care. Post-dilation maximum pupil diameter was also lower among these eyes (mean, -0.01 mm; 95% CI, -0.20 to -0.03).  Post-dilation constriction percentage was 0.57 percentage points greater (95% CI -1.38, 2.51) in eyes receiving the drops via the small eye drop adapter compared with eyes receiving the standard of care. Overall, the novel small volume eye drop adapter met the strict non-inferiority criteria for pupillary dilation, but failed to demonstrate non-inferiority for cycloplegia and constriction percentage. However, investigators determined that the small differences noted between the 2 methods were clinically insignificant. 

“Replacing standard eye drops with small volume eye drops has the potential to decrease medical waste, decrease local and systemic toxicity, and extend the number of doses of diagnostic and therapeutic ocular medications for both physicians and patients,” according to the study authors.  

Study limitations include a strict non-inferiority margin of 10% loss of treatment effect, dark irises among a majority of the cohort, failure to mask staff and participants, and failure to objectively measure systemic side effects and local irritation.