Detection of ocular surface abnormalities in experimental vitamin A deficiency

Hypovitaminosis A is the major cause of childhood blindness in many developing countries. Unfortunately, serum vitamin A levels do not accurately reflect liver stores, and there is no good objective test for detecting early, physiologically important deficiency. The purpose of this study was to determine if we could detect ocular surface abnormalities in the eyes of vitamin A-deficient rabbits at early stages of xerophthalmia. Cellulose acetate filter strip impressions were taken serially from the bulbar conjunctiva of vitamin A-deficient rabbits every two weeks, beginning eight to 12 weeks before keratinization of the corneal or conjunctival epithelium was clinically apparent. The percentage of light microscopic fields containing goblet cells decreased, and the percentage of fields containing enlarged epithelial cells increased in a linear fashion, beginning at least four to six weeks before the clinical changes. The results indicate that this technique may be of potential usefulness as a screening tool for early xerophthalmia.