Abstract
Purpose:
Serum 25 hydroxy vitamin D (25[OH]D) levels have been suggested to play a protective role against age-related macular degeneration (AMD) by suppressing inflammation and angiogenesis, two of the key mechanisms involved in AMD. However, the association is inconsistent in human studies. We examined the association of 25(OH)D levels with AMD in a sample of Asian adults.
Methods:
We conducted a population-based case-control study. AMD cases were Chinese, Malay and Indian adults aged 40-80 years who participated in the Singapore Epidemiology of Eye Diseases Study (2004-2011) and had any AMD (n=605, early = 548, late=57). Controls (n=1,265) were selected from the same study cohorts matched for age within a 5-year interval, gender and ethnicity. AMD was graded from retinal photographs according to the Wisconsin Age-Related Maculopathy Grading System. Serum 25(OH)D levels and parathyroid hormone (PTH) were measured using electrochemiluminescence Immunoassay. The association between 25(OH)D and AMD was examined using unconditional logistic regression models adjusted for age, sex, ethnicity, smoking, body mass index, blood pressure, total and high-density lipoprotein cholesterol and additionally for PTH levels.
Results:
AMD cases and controls had similar levels of 25(OH)D (mean (SD) = 24.3 (10.6) vs. 23.7 (11.5) µg/mL; p=0.2). Overall, 25(OH)D levels were not found to be associated with AMD in multivariable models. Compared to the lowest quartile of 25(OH)D (Q1, 4.0-15.3 ug/L), the multivariable odds ratio (95% confidence interval) of any AMD in Q4 (>31.1 ug/L) was 1.29 (0.94-1.78) and was 1.13 (0.82-1.57) additionally adjusting for PTH. No significant associations were observed when 25(OH)D was analyzed in clinically relevant categories (<10, 10-20, 20-30, ≥30 ug/L) or as a continuous variable and there was no interaction by smoking status (P-interaction-0.7) in the association between 25(OH)D and any AMD. In addition, there was no significant association of 25(OH)D with either early or late AMD or drusen or pigment lesions.<br />
Conclusions:
Elevated levels of serum 25(OH)D were not found to be associated with AMD in this population-based sample of Asian adults.