Eyedrop Bottle Adaptor May Make Drops Last Longer

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Eyedrop bottles equipped with a novel adaptor proved effective in delivering smaller drops than bottles with a stock bottle tip.¹ The Nanodropper (Nanodropper) also increased the total number of drops per bottle, thereby theoretically extending the life of a one-month supply to around 2.5 months.

“There are real limitations to the way we deliver ophthalmic medications with standard eyedrop bottles,” said Leonard K. Seibold, MD, at the University of Colorado School of Medicine in Aurora. Some patients run out of drops too soon, have trouble affording drops, or experience excessive side effects. “These issues can collectively lead to poor adherence, which in turn can lead to poor outcomes and even vision loss, in the case of glaucoma. One way to alleviate some of these issues is through the consistent delivery of smaller eyedrops with less waste, while prolonging the life of a bottle. The Nanodropper bottle adaptor is one way to achieve this.”

ADAPTOR TIP. Placed on a stock bottle, a specialized adaptor tip delivers more and smaller drops.

Adaptor versus standard drop volume. In this experimental study, the team tested the volume-reducing adaptor, which twists onto a compatible stock bottle, on nine ophthalmic medications: six topical ocular hypotensive drugs, one steroid, and two artificial tears emulsions. They determined average drop volume and total number of dispensed drops from bottles with and without the Nanodropper. The adaptor decreased drop volume by an average of 62.1%. Mean drop volume was 39.8 ± 2.1 µL for stock bottles versus 15.1 ± 1.0 µL for the Nanodropper. What’s more, the adaptor delivered 2.6 times the total number of drops per bottle for all medications. Stock bottles of 2.5 mL dispensed a mean of 69.8 ± 4.9 drops compared with 184.1 ± 15.1 drops with the adaptor. The adaptor was similarly effective for solutions, suspensions, and emulsions.

Ideal drop volume still unknown. Despite these robust findings, the study did not provide data on the efficacy of smaller drops. Clinical trials will have to address that issue, said Dr. Seibold. “However, when you consider the limited volume of the tear film and conjunctival cul-de-sac, it is likely that drop volume greater than 20 µL provides no real additional benefit.” He said this may explain why drops almost always roll down the cheek, no matter how accurately they are placed.

Clinical trials will also be necessary to address patient adherence and satisfaction with the adaptor, as well as IOP-lowering efficacy in patients with ocular hypertension and glaucoma, and cost analyses for medication use with and without the adaptor, he said.

A potential bonus. While the issue of medical waste was not part of the study, Dr. Seibold noted that by reducing the amount of medicine lost with each drop applied, the Nanodropper may theoretically reduce medical waste by more than 50%. 

—Miriam Karmel

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1 St. Peter DM et al. Med Devices: Evid Res. 2023;16:71-79.

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Relevant financial disclosures—Dr. Seibold: None.

For full disclosures and the disclosure key, see below.

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