Introduction & Objective: One of the important functions of the cornea is to maintain normal vision by refracting light onto the lens and retina. This property is dependent in part on the ability of the corneal epithelium to undergo continuous renewal. Ocular surface failure which follows a variety of endogenous and exogenous precipitating factors. the most common being: chemical trauma. https://www.roneverhart.com/Western-Digital-Re-WD6001FSYZ-6TB-7-2K-RPM-SATA-6Gb-s-128MB-3-5-Hard-Drive/