Squamous metaplasia, membrane

Epidermal keratinization and mucous membrane squamous metaplasia respond to both oral and topical vitamin A therapy. Vitamin A exists in three forms retinol, retinal, and retinoic acid.VitaminA increases the mucous production of goblet cells and perhaps the aqueous and lipid components of the tears as well. Tretinoin is a normal metabolite and the carboxylic form of retinol. Retinol is present in tears and the lacrimal gland appears to be its major provider. Retinoic acid has been shown to be effective in ocular surfece disorders such as squamous metaplasia by reversing the corneal and conjunctival keratinization and improving epithelium wound healing rate. 

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