INDIVIDUALISED THERAPY FOR GLAUCOMA PATIENTS

In addition to considering adherence, which is often poor for patients using topical glaucoma medications, ophthalmologists should also consider bottle exhaustion and refill rate when individualising therapy, Daniel B Moore MD told the 2011 annual meeting of the American Academy of Ophthalmology. About one-quarter of glaucoma patients surveyed at the University of Washington Eye Institute reported running out of eye drops before they were allowed to refill them at least once a year, with about eight per cent running out five or more times. Patients with visual acuity of 20/60 or less, no medication insurance, and those requiring an interpreter during medical visits were significantly more likely to report exhausting eye drop supplies on a regular basis.

“About eight per cent of patients in our study routinely exhausted eye drops early, making this an important cause of medical non-compliance,†Dr Moore said.

The cross-sectional non-randomised study involved 241 consecutive glaucoma patients with prescribed topical glaucoma therapy in both eyes who were stable, self-administered drops, and had no therapy changes in the prior three months. Interviewers administered a brief survey at office visits, asking subjects how many medications they took, how often they thought they ran out, and why they thought they ran out. Median age of study participants was 67.7 years; 53 per cent were male; and mean visual acuity and Humphrey visual field index were logMAR 0.135, or about 20/30. Mean duration of treatment was 7.6 years, and the mean number of drop bottles was two.

Overall, 72.9 per cent reported not running out of drops, while 10.8 per cent said they ran out once or twice a year, 7.1 per cent three or four times a year, 2.1 per cent five to seven times a year, 1.2 per cent eight to 11 times, and 5.0 per cent ran out always. Of those who reported running out, insufficient amount in the bottle was the leading reason given at 28.1 per cent, followed by more than one drop coming out at 21.9 per cent, inability to hold the bottle steady at 12.5 per cent, can’t see tip of bottle at 10.4 per cent. Drop size, bottle problems, missing the eye and miscellaneous reasons were also reported.

Poor visual acuity was the most significant risk factor. Dr Moore hypothesised that poor vision inhibits hand-eye coordination and may result in poor aim and drop size control. He noted that research has shown both are issues in topical medication adherence.

The relationship between the need for an interpreter and adherence is more complex, Dr Moore suggested. While research shows that in the US, non-English speaking patients may not seek medical attention until poor vision is apparent, one study also shows that they have higher compliance with clinic visits as open-angle glaucoma suspects. An analogous increase in medication adherence may help explain more-frequent bottle exhaustion in this population, he suggested. However, the study did not examine compliance rates among patients who did not report frequent bottle exhaustion.

Lack of insurance has frequently been associated with lower therapy adherence. Medication costs are a significant barrier, particularly among patients from less-affluent backgrounds, Dr Moore noted.

Age, sex, years of eye drop use, number of eye drops and bottles, presence of arthritis, number of co-morbid medical conditions and indices of visual fields were not significant risk factors in this study. The guidance this study contributes is valuable, but further research is needed to confirm or generalise the findings, Dr Moore said.