Vitamin D Deficiency Associated With Dry Eye Signs, Symptoms

Vitamin D Deficiency and Dry Eye

In addition to its well-known effects on bone and muscle, vitamin D plays a prominent role in gene regulation and is a potent immune modulator. It promotes innate immunity, indirectly regulates cytokine and immunoglobulin synthesis, and reduces inflammation.

Vitamin D deficiency (<20 ng/mL) and/or insufficiency (20-29 ng/mL) have been associated with a variety of health problems, from heart disease to ocular disorders such as optic neuropathy, myopia and AMD.

It has been shown that the cornea contains mRNA for vitamin D receptors and the enzyme that activates vitamin D (1 alpha-hydroxylase), as well as significant vitamin D concentrations. Experimentally, vitamin D is reported to enhance corneal epithelial barrier function.

These findings led researchers to examine whether vitamin D deficiency is related to dry eye and impaired tear function. The research team also asked whether dry eye is associated with the main symptoms of vitamin D deficiency: pain, fatigue and functional impairment such as muscle weakness (1).

Design & Methods

Fifty premenopausal women deficient in vitamin D (serum levels < 20 ng/mL) and 48 controls with serum vitamin D in the normal range (> 20 ng/mL) were included in this comparative study. Among the exclusion criteria was postmenopausal status, as hormonal changes may be associated with dry eye. Participants were assessed by Schirmer’s test, tear break-up time test (TBUT), ocular surface disease index (OSDI), Stanford Health Assessment Questionnaire (HAQ,) disability scale, fatigue severity scale (FSS), and visual analogue scale-pain (VAS-pain).

Results

Mean age did not differ between women with vitamin D deficiency and controls. Vitamin D level, Schirmer’s test and TBUT scores were lower, while OSDI, VAS-pain, HAQ and FSS scores were higher in the vitamin D deficient group than in the control group (all p< 0.001). In the vitamin deficient women, vitamin D level was negatively correlated with OSDI (p< 0.001), and positively correlated with Schirmer’s test and TBUT scores (p< 0.001 and p=0.001, respectively).

FSS (fatigue) was negatively correlated with both Schirmer’s test and TBUT scores (p= 0.038 and p= 0.002, respectively). VAS-pain was negatively correlated with TBUT scores (p= 0.023).

Of the vitamin deficient women, 52%, 74%, and 70% had dry eye according to the results of Schirmer’s test, TBUT, and OSDI respectively. The frequency of dry eye differed significantly between groups (see Table 3).

Comments

The finding of dry eye and impaired tear function in vitamin D deficient women could indicate a protective role for vitamin D in the development of dry eye, probably by enhancing tear film stability and reducing ocular surface inflammation, according to the authors. This could be of public health importance since the overall prevalence rate of vitamin D deficiency in US adults is estimated to be about 42%.

In the study, two of three major vitamin D deficiency symptoms correlated with dry eye parameters: fatigue with the amount of tears and the stability of the tear film layer, and pain with tear film layer stability.

Reference:

Yildirim P., et al. Dry eye in vitamin D deficiency: more than an incidental association. Int J Rheum Dis, Epub Aug 13, 2015.