A Cochrane review included 1 randomised trial with a cross-over design with 29 subjects. The study compared the use of an eye drop device to a standard bottle in people with rheumatoid arthritis suffering from persistent dry eyes. The proportions with observed difficulties when using the device to squeeze out drops and getting the drops in the eyes were 10% and 14%, respectively, compared to 52% and 52% when using the standard bottle (RR 0.22, 95% CI 0.06 to 0.62, NNT 3; RR 0.27, 95% CI 0.1 to 0.71, NNT 3, respectively).
The proportions of participants reporting difficulties with squeezing the bottle, controlling the number of drops, and aiming the drops when using the device were 40%, 44%, and 46% respectively, while using the standard bottle the proportions with difficulties were 72%, 84%, and 76% (RR 0.56, 95% CI 0.31 to 0.99, NNT 4; RR 0.61, 95% CI 0.37 to 1, NNT 4; RR 0.60, 95% CI 0.37 to 0.98, NNT 4, respectively). 17 out of 29 participants felt the device was very useful, and 9 that it was moderately useful. None of the 29 participants touched their eye with the bottle tip when using the dispenser device, whereas 22 (76%) of them did when using the standard bottle.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and lack of blinding).