Abstract
Abstract: :
Purpose: To determine whether vitamin E can prevent changes in the cornea and conjunctiva due to vitamin A deficiency. Methods: Male infant rats were fed a usual diet until 20 days of age and divided into two groups: Group 1 was fed a vitamin A deficient diet (A- rats). Group 2 was fed a vitamin A deficient diet and injected intraperitoneally with vitamin E, 15mg/week (A-E+ rats). At 13 weeks of age, the corneal and conjunctival changes of these rats were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results: The body weight of the A- rats was significantly lower than that of the A-E+ rats (P=0.0190, t-test comparison of means). The serum vitamin E level of the A- rats was significantly lower than that of the A-E+ rats (P=0.0448, t-test comparison of means). SEM showed more fine microvilli and clear cells in the most superficial epithelial layer of the cornea and conjunctiva in A-E+ rats than in A- rats. The surface of the cornea in A- rats was rough and uneven. Severe keratinization and many exfoliating cells were seen in the cornea and conjunctiva of A- rats, but these were rare in A-E+ rats. Numerous secretory granules were seen in the goblet cells of the conjunctiva of A-E+ rats, but in A- rats there was a total absence of conjunctival goblet cells. TEM showed severely keratinized corneal surfaces in A- rats, and dark wing cells and abnormal dense deposits were seen in the subepithelial layer, and the columnar appearance of the basal epithelial cells was lost. Abnormal vacuoles and dense bodies appeared in the basal portion of the basal cells in the corneas of A- rats, and the number of hemidesmosomes was decreased. Blood vessels were seen in the anterior stroma of the corneas of A- rats. On the other hand, the corneas of A-E+ rats were almost normal in appearance. The conjunctivae of A- rats had superficial epithelial keratinization, scarce goblet cells, and many abnormal dense deposits and dark cells, while in the conjunctivae of A-E+ rats there were numerous secretory granules in goblet cells and some dark cells. Conclusions: The present study suggests that vitamin E has a protective effect against the corneal and conjunctival damage caused by vitamin A-deficiency.
Keywords: 627 vitamin A deficiency • 472 microscopy: electron microscopy • 372 cornea: epithelium