Serum Vitamin D Levels and Dry Eye Disease in Postmenopausal Women: A Case-Control Study at a Tertiary Care Center in Rural Haryana

Background: Despite the high prevalence of Vitamin-D insufficiency and high susceptibility to dry eye disease (DED) in postmenopausal women (PMW), correlation between DED and Vitamin D has not been explored in PMW in any Indian study.

Aims and objectives: To explore the correlation between serum Vitamin D levels in PMW with and without DED, in a hospital-based population in rural Haryana.

Materials and methods: Subjective (ocular surface disease index [OSDI] questionnaire) and objective clinical tests were undertaken for DED diagnosis. 25(OH) Vitamin D was measured in serum using enzyme-linked immunosorbent assay; insufficient (10-30 ng/ml) and deficient (<10 ng/ml). Descriptive statistics were analyzed by mean ± standard deviation for continuous and frequencies for the categorical variables; Student's t-test used to find out mean difference in Vitamin D levels; P < 0.05 was considered statistically significant.

Results: One hundred and forty PMW (60.1 ± 5.32 years) were included; Group-A (Controls; no DED; n: 70); Group-B (Cases; DED diagnosed by OSDI scores; n: 70); Subgroup-B1 (clinical tests negative; n: 30) and B2 (clinical tests positive; n: 40). There was no statistically significant difference in OSDI scores between B1 and B2. Significantly lower mean Vitamin D levels were found in cases (14.36 ± 4.08 ng/ml) as compared to controls (19.19 ± 6.4 ng/ml) (P = 0.001) and in B2 (13.15 ± 3.51 ng/ml) as compared to B1 (15.57 ± 4.66 ng/ml) (P = 0.01).

Conclusion: There were significantly low levels of Vitamin-D in clinically established DED. Evaluating Vitamin D levels as a part of the dry eye workup in PMW is recommended. OSDI scores were not aligned with the clinical test scores; questionnaire-based tests alone may not be sufficient for diagnosing DED.