Dry eye symptom questionnaires show adequate measurement precision and psychometric validity for clinical assessment of vision-related quality of life in glaucoma patients

PURPOSE: To ascertain the presence of Dry Eye Syndrome (DES) in patients being treated for glaucoma, using subjective and objective methods and to examine DES impact on their quality of life (QOL). METHOD: A cross-sectional study was conducted by employing 156 glaucoma patients recruited from treatment centers in the Cape Coast Metropolis in Ghana. All the participants underwent dry eye examination and completed the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ), the Dry Eye-related Quality of Life Score (DEQS) and the Ocular Surface Disease Index (OSDI). Comparisons of the clinical tests, NEI VFQ-25 subscale item and composite scores and scores of DEQS and OSDI were made among subgroups divided according to the presence of dry eye symptoms or signs. Multivariate logistic regression analysis was performed to investigate the factors that influence DES related-QOL among the patients. RESULTS: The study involved 156 subjects with a mean age of 47.88 ± 16.0 years and made up of 81 (51.9%) females and 75 (48.1%) males. A One-Way ANOVA was conducted, and the F-statistic (F) indicated that there was a significant difference in the mean scores of the groups. There were significantly lower Tear break-up time (TBUT) values found in the group with definite dry compared with the group without DES and the group that was symptomatic with no signs DES in both eyes, [(F(3,151) = 13.703, p<0.001 (RE): (F(3,152) = 18.992, p<0.001 (LE)]. Similar results were found for Schirmer test (ST) [(F (3,151) = 28.895, p<0.001 (RE): (F (3,152) = 17.410, p<0.001 (LE)]. There was statistically significant difference in the mean composite score (64.93 ± 20.27) for the NEI VFQ-25 and sub-scale score of ocular pain, which was significantly lower in the group with definite dry as compared to other sub-groups (F(3,152) = 4.559, p = 0.004). OSDI scores of the group with definite dry eye (47.69–19.17) and the group that was symptomatic but with no signs (38.90–22.44) were significantly higher than those without dry eye and those that were asymptomatic but had a sign (F(3,152) = 17.896, p<0.001), with a similar trend occurring in the groups with relation to DEQS scores (F(3,152) = 8.775, p<0.001). There was a strong correlation between the DEQS and the OSDI questionnaires, and a weak correlation between the DEQS and the NEI VFQ-25 questionnaire after adjusting for all other factors (all p < 0.01). CONCLUSION: The study established a high presence of DES and consequently low DES related-QOL in glaucoma patients. Dry eye questionnaires are able to discriminate those who have definite dry eye from the other groups, showing its appropriateness for clinical use in glaucoma patients. Ocular surface evaluation should be conducted among glaucoma patients on topical anti-glaucoma therapy to ensure the timely detection and treatment of signs and symptoms of DES and improvement of dry-eye related QOL.