Reduction of Eyedrop Volume for Topical Ophthalmic Medications with the Nanodropper Bottle Adaptor

PURPOSE: To determine the drop volume and total number of dispensed drops using the Nanodropper eyedrop bottle adaptor (Nanodropper, Inc.) compared to drops dispensed from stock bottles to potentially limit ocular toxicity of these eyedrops and prolong bottle use. PATIENTS AND METHODS: Six topical ocular hypotensive medications (5 solutions, 1 suspension), one steroid (suspension) and two artificial tears emulsions were selected for this study. An analytical balance was used to determine the mass per 10 drops with and without the volume-reducing adaptor and repeated until the bottles were completely emptied. The density of each product was determined using the calculated density. The average drop volume and number of drops per bottle for the nine medications were compared with and without the adaptor with paired t-testing. RESULTS: When all medications were assessed, the drops delivered with the adaptor were 62.1% smaller than eyedrops administered from standard bottles. Compared to stock bottle eyedrops, which had a mean volume of 39.8 ± 2.1 μL, the adaptor resulted in drops with a mean volume of 15.1 ± 1.0 μL, p<0.0001. The adaptor delivered 2.6x the number of drops dispensed from a standard 2.5 mL bottle (184.1 ± 15.1 drops with adaptor and 69.8 ± 4.9 drops from stock bottle, p<0.0001). CONCLUSION: The Nanodropper eyedrop bottle adaptor can significantly reduce drop volume and increase the overall number of drops dispensed compared with stock eyedrop bottles. Further studies are needed to elucidate the clinical impact of utilizing decreased drop volume with direct comparison to current standards of care.