Abstract
Purpose Dry eye disease (DED) is associated with decreased visual function, such as deterioration in reading speed. Changes in visual function in individuals with meibomian gland dysfunction (MGD), which is commonly associated with evaporative DED, have not been well studied. This study evaluated best-corrected visual acuity (BCVA) and reading speed in individuals with and without MGD. Methods In a 22-day, prospective, noninterventional, multicenter (three sites) clinical study (NCT01979887), eligible adults (age ≥40 years with no uncontrolled ocular or systemic disease other than MGD) were classified into one of three cohorts (non-MGD, mild/moderate MGD, and severe MGD) based on meibum quality scores, ocular symptom scores, and Schirmer test results. Visual function tests included BCVA in the study eye and reading speed evaluated using the International Reading Speed Texts (IReST) tool with both eyes refracted for best correction at 40 cm. The average of measurements from days one and 22 was used for analysis, and nominal p values were reported. Results Seventy-five individuals were assigned to the cohorts (25 per cohort). Overall, the mean age of the subjects was 54.5 years, and 66.7% (50/75) were women. Mean Schirmer (without anesthesia) test scores in the study eye ranged from 16.4 to 18.6 mm among cohorts, indicating that, on average, the subjects were not aqueous deficient. Mean BCVA was 89.9, 88.3, and 82.7 letters in the non-MGD, mild/moderate MGD, and severe MGD cohorts, respectively (p= 0.046 severe vs mild/moderate MGD; p= 0.094 severe MGD vs non-MGD). Mean IReST reading speed was slower in the severe MGD cohort (146.0 words/min) than in the non-MGD (164.2 words/min) and mild/moderate MGD (167.8 words/min) cohorts, and the difference between the mild/moderate and severe MGD cohorts was significant (p= 0.046). Conclusions Tear film stability is important for the maintenance of visual performance. Both BCVA and reading speed were reduced in patients with severe MGD. For patients with MGD (as defined in this protocol) and visual complaints, reading speed testing in the office may be beneficial to detect patients' difficulty with visual tasks in everyday life.