الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Cornea has an important barrier function and is responsible for the majority of the eye’s refractive power. The corneal epithelium acts as a water tight seal and an impediment to pathogenic organisms. Since the corneal epithelium is exposed, it is susceptible to common ocular pathologies such as abrasions and corneal epithelial defects Healthy corneal epithelial cells are regenerated from stem cells at the limbus, with an average life span and self-renewal rate of 7 to 10 days Therefore, an acute epithelial defect in healthy cornea usually heals within 7 to 14 days. Resistant corneal ulcers are defined as corneal defects with a minimum area of 2 mm2 that continue without improvement for more than 2 weeks despite conventional treatment.