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In an effort to provide a comprehensive analysis of the effect of vitamin D on eye health, researchers in Hong Kong set out to conduct a systematic review of the topic. Although some studies were hampered by significant limitations, they found evidence of an association between vitamin D and age-related macular degeneration (AMD), diabetic retinopathy (DR), and dry eye syndrome (DES).1
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IMPACT ON AMD. Although evidence from cross-sectional studies suggests that vitamin D may protect against AMD development, this effect is small or may only apply to specific populations. This image was originally published in the ASRS Retina Image Bank. James B. Soque, CRA, OCT-C, COA, FOPS, and Pamela Weber, MD. Exudative Macular Degeneration, Prominent Plaque – FA Early. Retina Image Bank. 2012; Image Number 1186. © The American Society of Retina Specialists.
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Study rationale. “Because vitamin D participates in a wide variety of actions [in the body], it is important for maintaining our [overall] health,” said Jason C. Yam, MD, at the Chinese University of Hong Kong. “We hypothesized that vitamin D is important for ocular health.” Indeed, a number of recently published studies have investigated the relationship between serum vitamin D levels and ocular disease.
Findings and limitations. Dr. Yam and his coauthors searched two databases and found 162 published studies eligible for their review. Of 27 studies on AMD, 17 reported an association with vitamin D. In addition, 48 of 54 studies reported a link with DR, and 25 of 27 studies reported an association with DES. The available evidence for an association with other ocular disease is limited.
However, as Dr. Yam noted, “Currently, there is not any standardized protocol for conducting vitamin D research” in ophthalmology. For instance, different studies had different cut-off levels for vitamin D deficiency and insufficiency. Given the varying analysis methods used, as well as the inconsistent findings for some ocular diseases, “it is difficult for us to draw a conclusion on whether vitamin D has a role in some ocular diseases,” Dr. Yam said.
Need for standardization. In the future, researchers will need to carefully consider different potential confounders such as sunlight intensity and duration of exposure, Dr. Yam noted. Thus, “before conducting more studies, we may need a standard protocol and questionnaire for collecting the data and accounting for confounding factors.”
—Jean Shaw
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1 Chan H-N et al. Int J Mol Sci. 2022;23:4226.
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Relevant financial disclosures: Dr. Yam—None.
For full disclosures and the disclosure key, see below.
Full Financial Disclosures
Dr. Bellsmith NIH: S; Research to Prevent Blindness: S.
Dr. Galor AstraZeneca: C; Dompé: C; Eye Cool: C; Novartis: C; Ocular Therapeutix: C; Tarsus: C.
Dr. Scott Allergan: S; NEI: S; Regeneron: C,S.
Dr. Thomas NIH: S; Research to Prevent Blindness: S.
Dr. Yam None.
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