Many patients struggle to correctly instill their eye drops, especially those with low vision.1 This study examined whether a nose-pivoted delivery device (NPDD) could improve drop instillation in patients with visual acuity worse than 20/60 or with visual fields worse than 20 degrees in the better seeing eye. The NPDD is a silicone alignment aid with a sleeve that fits around the eye drop bottle and an extended portion that rest on the bridge of the nose stabilizing the bottle over the ocular surface during drop instillation.2
Thirty participants were recruited, and video recorded self-administering drops of artificial tears in both eyes using their usual technique. A short teaching session was then provided including advice on a traditional eye drop instillation technique and instruction in how to use the NPDD. Participants were then asked to instill eye drops using the traditional technique and using the NPDD, with the order randomized. Videos were graded and primary success defined as an eye drop reaching the eye without the bottle touching the eye or periocular surface.
At baseline a high proportion of participants struggled instilling drops, with an eye drop reaching the ocular surface in only 64%. Forty percent touched the ocular or periocular surface with the bottle tip, and a mean of 2.4 drops were dispensed per instillation attempt. Use of the NPDD improved successful drop delivery from 52% to 76% (P = 0.013) and reduced medication wastage. Contact between the bottle tip and eye or periocular region decreased to only 14% and contact with the eye decreased from 21% to 0%. In addition, 73% of participants preferred the NPDD to the traditional method and this figure was 94% among those who reported difficulty using eye drops. There was also an improvement in ease-of-use scores, self-perceived success, and all participants would recommend the device to others.
The proportion of eye drops successfully reaching the eye was actually lower using the nose-pivoted delivery device, though this was not statistically significant (64% versus 59%)
Although the NPDD improved success, improvement was driven by the reduction in contact between the bottle tip and eye. The proportion of eye drops successfully reaching the eye was actually lower using the NPDD, though this was not statistically significant (64% versus 59%). The high proportion of patients with low vision unable to deliver an eye drop to the eye highlights the need of improved methods of drug delivery in this vulnerable population, who are likely at high risk of further functionally significant visual loss if they are not receiving medications as intended.
While the NPDD reduced bottle tip contact, improved patients' perception of ease of use and confidence in eye drop self-administration, the failure to increase the proportion successfully delivering a drop to the ocular surface is disappointing. A bottle tip touching the ocular surface may have no detrimental effect on treatment efficacy but successful drop delivery to the ocular surface is essential. The study importantly highlights difficulties in eye drop administration as a major barrier to effective glaucoma treatment and clinicians should be aware of this common limitation of topical therapy, especially when considering treatment options in those with low vision.
Although in this small study the NPDD did not improve the proportion of patients with low vison able to successfully deliver a drop to the ocular surface, patients were extremely satisfied with the device and preferred it to their traditional drop instillation method. It would be interesting to explore if longer periods of practice using the NPDD improve performance as in the current study participants were only permitted a few minutes with the device.