The root cause of contact lens discomfort can run the gamut, from improper care to dry eye, allergies, environmental factors and even infection. Refitting symptomatic monthly contact lens wearers with a daily disposable option may reduce symptoms related to contact lens discomfort, but new research now suggests that reduction may be due, in part, to a placebo effect.

The study included 31 monthly contact lens wearers who were about 23 years old and symptomatic based on results of the Contact Lens Dry Eye Questionnaire 8 (CLDEQ-8). The participants were placed into two groups: 14 patients who were prescribed daily disposable lenses and 17 individuals who were masked to the fact they were wearing their regular monthly lens. The investigators assessed the patients at one month, at which time the monthly lens wearers were given daily disposables and evaluated again one month later. Researchers recorded symptoms with the CLDEQ-8 and global rating of change scale (GRCS), and evaluated non-invasive tear break-up time, conjunctival hyperemia, fluorescein staining and lid wiper epitheliopathy.

After one month of wearing daily disposables, the study group showed an improvement of -39.6±25.8% in CLDEQ-8 and 31.3±14.6 points in the GRCS, although they had no changes in clinical tests.

In the control group, symptoms improved significantly after wearing the masked monthly contact lens: CLDEQ-8 improged by -26.1±31.0% and GRCS was 14.9±17.0. However, researchers observed a worsening in bulbar (26.5±40.0%) and limbal hyperemia (21.6±34.7%), and an improvement of -19.1±37.0% in lid wiper epitheliopathy. When the control group was fitted with the daily disposable, patients had improvements in GRCS (20.5±25.5), non-invasive tear break-up time (37.9±42.3%) and conjunctival staining (-47.1±59.9%).

Although daily disposable lenses can improve patients’ wearing experience, “clinicians and researchers must be aware of the existence of a placebo effect when assessing the effectiveness of any CL refitting,” the researchers concluded.