Study: Vitamin D (2015, 2016) & Dry Eyes
Learn more about dry eyes.
A large study evaluated more than 17,000 patients older than 19 in Korea. They were selected randomly from the Korean National Health and Nutrition Examination Survey 2010-2012. The researchers associated low levels of vitamin D with greater incidence of dry eye syndrome.
Note: another study also investigated a large sample from the same survey, and found only a weak connection between vitamin D and dry eye syndrome. However this study did not take into account many factors including gender, region of residence, other health conditions, and amount and type of exercise.
Researchers: S.Y. Yoon, et al
Published: Low Serum 25-Hydroxyvitamin D Levels Are Associated with Dry Eye Syndrome, PLoS One, January, 2016
Researchers found not only that dry eye syndrome is associated with low levels of vitamin D, but that the evaporative type of dry eye syndrome is linked to specific changes in the structure of the cornea.
They found that the density of corneal nerve cells was lower in patients with dry eye; that corneal nerve cells were shorter and thinner, and total area covered by nerve cells was less. In addition, the branch nerves supplying the cornea were also less dense.
Researchers: R. Shetty, et al
Published: Corneal Dendritic Cell Density Is Associated with Subbasal Nerve Plexus Features, Ocular Surface Disease Index, and Serum Vitamin D in Evaporative Dry Eye Disease, BioMed Research International, February, 2016.
Because it is known that the cornea contains receptors to recognize vitamin D and an enzyme catalyst for vitamin D, researchers wanted to know whether the vitamin is also tied to dry eye syndrome.
Scientists assessed the eye condition of 50 women (not menopausal) who were deficient in vitamin D. They used a number of standard tests that measure relevant information including the OSDI test, a standard measure of chronic dry eye, a test of eye pain, a health assessment questionnaire, and a scale which assesses the impact of fatigue on one's life.
Compared to control, the patients with vitamin D deficiency had markedly poorer results for all of these scales - with 52% having dry eye, 74% having weaker general health, and 70% having chronic dry eye.
Symptoms of dry eye: inadequate tear film, unstable tear film, and pain were coorelated with deficiency of vitamin D.
Researchers: P. Yildirim, et al.
Published: Dry eye in vitamin D deficiency: more than an incidental association. International Journal of Rheumatic Disease, 2015.