October 2015

 

NEWS & OPINION

 

Delving into vitamin D, eye health studies


 
   

Delving into vitamin D, eye health studies

The number of studies focusing on vitamin D and eye conditions ranging from AMD to dry eye to glaucoma is still small. Here are details on 3 recently published studies in the ophthalmic literature to provide a flavor of whats been reported so far.

Vitamin D, AMD, and genetic risk

In a study published online in August, researchers, led by Amy E. Millen, PhD, University at Buffalo, Buffalo, N.Y., worked with the premise that vitamin D deficiency has been associated with increased odds of AMD.1 They then analyzed if the association is modified by a genetic risk for AMD and what association there may be between AMD and single-nucleotide polymorphisms of genes associated with vitamin D transport, metabolism, and genomic function.

Researchers included 913 postmenopausal women who were part of the Carotenoids in Age-Related Eye Disease Study and had available vitamin D concentrations. The women were also evaluated for AMD signs via fundus photographs. A 6.7-fold increased odds of AMD was observed among women with deficient vitamin D status, the researchers wrote. These women also had 2 risk alleles for the CFH and CFI genotypes.

Vitamin D and IOP

In a study published last year and led by Dr. Krefting, researchers examined associations between vitamin D levels and intraocular pressure (IOP).2 Healthy Caucasians with high or low vitamin D levels were recruited from a population-based study and had their IOP measured. Subjects with low D levels were randomized to receive vitamin D3 capsules of 20,000 IU twice a week or a placebo. The IOP was measured 6 months later. The IOP in 87 participants with low D levels did not differ from the IOP in the 42 participants with high D levels. Based on the results, the researchers said that vitamin D did not appear to play a role in the regulation of IOP.

However, Dr. Krefting believes it would be of interest to explore these findings further. One idea is to investigate if there is a relationship between IOP and levels of vitamin D among those persons with an elevated IOP. It also would be of great interest to do a randomized controlled study to see if there is a link between vitamin D levels and the rate of progression among patients with glaucoma, he said.

Dry eye, vitamin D, and a Mediterranean diet

Researchers at the Miami VAMC and Bascom Palmer Eye Institute, led by Dr. Galor, examined in a May 2014 study if a Mediterranean diet and vitamin D levels affected dry eye syndrome.3 The Mediterranean diet focuses for the most part on plant-based, healthy eating.

Nearly 250 male patients (mean age, 69 years) from the Miami Veterans Affairs eye clinic with normal eye health participated in the study and filled out a food frequency questionnaire as well as a Dry Eye Questionnaire. Researchers also measured levels of 25-hydroxy vitamin D and various dry eye parameters.

Adherence to a Mediterranean diet was positively associated with a risk for dry eye syndrome. Vitamin D levels had a small but favorable effect on the presence of dry eye symptoms.

We didnt find anything that exciting, Dr. Galor said. She and her fellow researchers were considering the need for a clinical trial but decided not to pursue it. She thinks omega-3 supplementation may be more of a superstar within ocular surface disease health going forward.

References

1. Millen AE, Meyers KJ, Liu Z, et al. Association between vitamin D status and age-related macular degeneration by genetic risk. JAMA Ophthalmology. 2015 Aug 27. [Epub ahead of print] 2. Krefting EA, Jorde R, Christoffersen T, Grimnes G. Vitamin D and intraocular pressureresults from a case-control and an intervention study. Acta Ophthalmol. 2014;92:345349.

3. Galor A, Gardener H, Pouyeh B, Feuer W, Florez H. Effect of a Mediterranean dietary pattern and vitamin D levels on dry eye syndrome. Cornea. 2014;33:437441.

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