Effect of Systemic Ingestion of Vitamin and Trace Element Dietry Supplements on the Stability of the Pre-Corneal Tear Film in Normal Subjects

Abstract

Inadequate ingestion of specific vitamins and trace elements are commonly cited as pre-requisites in the development of some dry eyes. It is well documented that the health of the anterior eye is highly dependant upon diet. In particular, third world studies have identified vitamin A deficiency leads to non-wettability of the ocular surface in turn leading to severe desiccation (xerophthalmia), corneal scarring and a high risk of ocular morbidity. There are several indications that vitamin A is vital for the number, and hence secretory activity, of the conjunctival goblet cells ^1–3. Restoration of systemic vitamin A results in a rapid resolution of the dry eye state in the presence of sufficient protein². Certain systemic conditions with associated dry eye symptoms also allow other dietary factors to be identified as being important for the health or homeostasis of the tear film (e.g. zinc, manganese, niacin, vitamins B6 and C etc.) These are important in relation to the composition of the glandular secretions which constitute the tear film because their absorption either:

• i) directly or indirectly affects the composition or,

• ii) affects the transport of essential metabolites for the tear constituents^4–7.

In a diet-healthy normal population, xerophthalmia is not prevalent but the marginal dry eye (e.g. KCS) certainly is. It can be proposed that the marginal dry eye condition is due to sub-clinical marginal dietary imbalances. A far as we know, this has not been proven, this rationale has yet to be established on a scientific basis.