I am very fortunate to practice in a setting where my patients’ full medical history and drug therapy is readily available via their electronic health record (EHR). I have noticed that many patients (including myself) have been prescribed oral vitamin D supplements (cholecalciferol) to boost their serum levels of vitamin D. This brings up a separate discussion: Why is there such a common deficiency of vitamin D in our patients, and is this a lifestyle challenge?

The Studies

The association between dry eye disease (DED) and vitamin D deficiency has been established in more than one study (Yildirim et al, 2016; Demirci et al, 2018). Recent data demonstrated that vitamin D deficiency may lead to dry eye, causing conjunctival squamous metaplasia and loss of goblet cells on the ocular surface (Dikci et al, 2020).

In addition, a March 2019 study in Cornea investigated the efficacy of topical carbomer-based lipid-containing artificial tears (CLATs) and sodium hyaluronate (HU)—for patients who had DED—based on serum D levels and cholecalciferol supplementation (Hwang et al, 2019). The participants were divided into the vitamin D deficient (VDD) group and the non-VDD group according to their serum vitamin D levels. In these study subjects, the Ocular Surface Disease Index (OSDI) and visual analog pain scale scores of both VDD and non-VDD groups decreased after application of topical CLATs and HU compared with baseline values. Tear breakup time (TBUT), corneal fluorescein staining score, and lid hyperemia in the VDD group remained unaffected by topical CLATs and HU, whereas those in the non-VDD group were improved.

The data of this study suggest that the effect of topical CLATs and HU was dependent on serum vitamin D levels. The authors conclude that cholecalciferol supplementation enhanced the efficacy of topical treatment and may be a useful adjuvant therapy for patients who have DED refractory to topical lubricants.

Furthermore, one meta-analysis of observational studies was conducted to elucidate the overall relationship between vitamin D and DED in the adult population (Askari et al, 2020). A total of 14 studies out of 252 met the inclusion criteria and were included in this systematic review and meta-analysis. Serum D3 was lower in DED subjects compared to healthy ones. In the final analysis, vitamin D correlated significantly with OSDI. The meta-analysis authors conclude that serum vitamin D was at a significantly lower level in DED patients and was correlated with OSDI but with no other DED parameter. These findings add to the existing literature supporting the concept that nutrition, especially vitamin D, plays an important role in human eye health.

Vitamin D Testing?

Summarizing, the research indicates that the eyes of patients who have better vitamin D levels feel better, and artificial tears seem to work better for these patients.

Should vitamin D serum testing be part of our DED workup? Is vitamin D supplementation prophylactic for DED? Hopefully our own clinical data and observations, along with targeted research, can answer these questions. Until then, I plan to explore this avenue of nutritional therapy for my ocular surface disease patients. CLS

For references, please visit www.clspectrum.com/references and click on document #298.