Eye drop instillation capability and hand function in glaucoma patients

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Patients who need to instill therapeutic eye drops have historically had difficulties getting the drops to hit their mark. However, a recent study found that, given the use of repetitive exercises before drop instillation, that difficulty may decrease and improve the successful instillation of eye drops, according to first authors Madeline Kate Weber and Paula Newman-Casey, MD, from the University of Michigan, who reported their results at the American Glaucoma Society annual meeting in Huntington Beach, CA.

Weber and Newman-Casey cited a previous study that reported that about 33% of patients with glaucoma patients have difficulty with successfully instilling their eye drops,¹ which emphasizes the need to investigate ways to improve the success rate.

The researchers commented, “There is a gap in our understanding of the specific challenges glaucoma patients encounter when instilling eye drops, especially regarding sensorimotor factors such as hand function.”

To better understand and possibly overcome this problem, the investigators conducted a pilot study to assess eye drop instillation performance and hand function in glaucoma patients who instilled daily medicated eye drops. The results then were compared to healthy controls who did not use daily eye drops.

The parameters that the investigators looked at were the location and the number of the dispensed eye drops and if there was contact between the bottle containing the drops and the ocular adnexa. Each participant underwent 18 instillation trials.

The following tests were performed: function and dexterity using grip strength and pinch force, the grooved pegboard test, and the arthritis hand function test.

Twenty patients with glaucoma (mean age, 76.6 ± 5.6 years) and 68 controls (mean age, 72.8 ± 5.6) participated in the study.

The analysis indicated that the proportion of successful drop instillations into the eye did not differ significantly between the glaucoma patients and control groups (0.95 vs 0.90, respectively; p=0.26); however, the glaucoma patients used fewer drops on average per trial (1.25 vs 1.41; p=0.05).

The results also showed no significant difference between the groups in the number of times the medication bottle touched the ocular adnexa.

One significant difference was that the glaucoma patients had weaker mean grip strength (21.1 vs 27.9 kg; p=0.03) and pinch force (4.6 vs 6.1 kg; p=0.02) and required more time to complete the grooved pegboard (116 vs 84 seconds; p=0.005) and arthritis hand function (146 vs 121 seconds; p=0.02) tests.

“Our findings indicated that although glaucoma patients are likely to have motor deficits due to older age, through repetitive practice of daily eye drop application, patients can improve their technique and overcome these motor deficits. These data demonstrate the potential utility in an individualized approach to teaching eye drop instillation the first time medicated eye drops are prescribed,” the investigators reported.

The take-home message is that even though the patients demonstrated worse hand function, they ultimately overcame that deficit with repetitive trials and successfully instilled their medication in the eyes. This indicated that an individualized approach to patients can improve the patients’ ability to correctly instill their drops.

Reference:

1. Hennessy AL, Katz J, Covert D, et al. A video study of drop instillation in both glaucoma and retina patients with visual impairment. Am J Ophthalmol. 2011;152:982-8.