Role of vitamin A in the healing process of alkali caused corneal injury of adult male albino rat: Histological and immunohistochemical study

Abstract

Background and Aim: Alkali burn of the cornea is considered as the most dangerous injury to the eye. It causes cornealinfection, ulceration, perforation, neovascularization (NV) and opacification. Vitamin A is necessary for the normal growth and differentiation of epithelium; it is expected to promote the mechanical repair of corneal epithelial defectsThe present study is planned to investigate the effect of vitamin A eyegel on wound healing of the corneal alkali burn in rats. Materials and Methods: A total of thirty male albino rats were used. Rats were divided randomly into four groups: Group I,the control group; included three rats, received distilled water. Each of group II, III, IV included 9 rats: their central corneas of the right eyes were injured by contacting them with filter paper saturated with 0.01 m NaOH for 45 seconds. Group II, the non-treated group, injured and received distilled water. Group III, the antibiotic treated group, received antibiotic eye drops (lincomycin hydrochloride eye drops) 3 times per day for 3 days. Group IV, vitamin A treated group, received the same course of antibiotic and vitamin A eye gel (Hypotear gel 1000 IU/g) three times per day. for 3 days. The eyeball was taken out, rapidly fixed and processed for light microscopic, immunohistochemical and morphometric studies. Specimens were taken after 24,48 and 72 hr. post-injury for tissue preparation and study of structural changes and immuno-histochemical analysis using Ki67 (detection of cellular proliferation) and transforming growth factor – beta (TGF-β) which is one of the most critical growth factors in establishing the pathologic lesion after corneal alkali burn. Results: Hematoxylin and eosin stained sections showed rapid healing of corneal ulcer in vitamin A treated group, with absence of neo-vasculariztion and inflammatory cellular infiltration. Immunohistochemical results showed that the use of vitamin A enhance cell proliferation (detected with Ki67) and decrease the expression of TGF-β which is one of the most critical growth factors in establishing the pathological lesion after corneal alkali burn.Conclusions: Vitamin A eye gel helped rapid healing of corneal alkali burn. This effect may be due to its anti-inflammatoryeffect and stimulation of cell proliferation.