Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. Many wearers of contact lenses use lubricating drops to ease the discomfort they feel with the lens, but how effective are these drops? Here’s lead author of the September 2024 Cochrane review, Barbara Caffery from Toronto Eye Care in Canada, to tell us about the evidence.

Barbara: Thank you Mike. Discomfort is one of the more common symptoms experienced by contact lens wearers, and it may be reported as lens awareness, dryness, or generalized irritation. Estimates of how many wearers are affected vary widely, from 13% to 75%, but we know it is a major contributing factor to people discontinuing contact lens wear. Practitioners and patients often turn to over-the-counter lubricating drops, but little is known about the success of these drops, what (if any) type of drop is best, whether these drops should be prescribed routinely before the onset of symptoms or signs, and what dosage is appropriate. Practitioners strive to make evidence-based decisions for their patients, hence the need for our synthesis of the evidence in this Cochrane Review.
We looked for randomized trials that had tested lubricating drops to reduce contact lens discomfort and recorded changes in discomfort using a validated questionnaire or a common scale at one to four weeks of follow-up. We were also interested in objective signs of discomfort, including corneal staining with fluorescein and redness of the conjunctiva.
After searching extensively through May 2024, we found seven randomized trials involving 463 adults. These had been done in France, Spain, Canada, and the USA. Four trials allocated participants to either lubricating drops (one used saline) or no treatment, while the other three compared the effects of lubricating drops to saline. The trials show that lubricating drops may reduce patient-reported contact lens discomfort compared to no treatment but that there was no clear difference between lubricating drops and saline. For the objective outcomes, there was no evidence of a difference in changes in the corneal fluorescein staining or conjunctival redness scores for drops compared to no treatment, and none of the studies reported microbial keratitis or inflammatory corneal infiltrates.
Overall, we found the quality of evidence to be very uncertain. This was because of the use of non-validated instruments for measuring discomfort and an inability or lack of clarity about whether trial participants knew which group they had been allocated to. Also, one trial compared treated and non-treated subjects only at the end of the study, and one trial did not provide results for the untreated control group.
In summary, we’ve shown that, currently, there is very low certainty evidence that lubricating drops may improve contact lens discomfort as compared to no treatment and that lubricating drops are likely to result in little to no difference in their effect on contact lens discomfort compared with saline.

Mike: Thanks Barbara. If listeners would like to learn more about this evidence, you can find the review online at CochraneLibrary.com with a search for ‘lubricating drops for contact lens discomfort.’