Comparison of blood levels of vitamin B12, folic acid, riboflavin, and homocysteine in keratoconus and healthy subjects.

PURPOSE: To evaluate blood levels of vitamin B12, folic acid, riboflavin, and homocysteine in keratoconus (KC) and healthy subjects. SETTING: Eskisehir Osmangazi University, Eskisehir, Turkey. DESIGN: Cross-sectional study. METHODS: 100 KC patients (patient group) between the ages of 18 to 35 years and 200 healthy individuals (control group) in the same age range were included in the Eskisehir Osmangazi University Hospital Eye Clinic between October 2019 and March 2020. In all cases, a complete ophthalmologic examination and corneal tomography evaluation with a Pentacam Scheimpflug camera were performed. In blood samples, vitamin B12 and folic acid levels were measured using an electrochemiluminescence immunoassay analyzer, and homocysteine and riboflavin levels were measured using high-performance liquid chromatography. Chi-square tests were used in the analysis of categorical variables, and Mann-Whitney U and Kruskal-Wallis tests were used in the analysis of numerical variables. RESULTS: Homocysteine (13.0 ± 6.6 vs 12.1 ± 5.4 µmol/L, P = .190), vitamin B12 (313.5 ± 119.4 vs 322.9 ± 128.3 pg/mL, P = .619), and folic acid (7.0 ± 2.7 vs 7.4 ± 2.9 ng/mL, P = .230) levels were not different between KC (100 eyes of 100 subjects) and control (200 eyes of 200 subjects) groups. The mean riboflavin level was 84.0 ± 21.8 µg/L in the patient group and 183.6 ± 74.3 µg/L in the control group, with a significant difference between the 2 groups ( P < .001). Riboflavin levels were below 180 µg/L in 99% (n = 99) of the cases in the KC group and 53.5% (n = 107) in the control group ( P < .001). CONCLUSIONS: Low blood riboflavin levels in KC patients may be a possible risk factor in the pathogenesis of KC.