 In developing countries, children afflicted by Vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes, which may persist lifelong.In ophthalmology, a corneal ulcer usually refers to having an infectious cause while the term corneal abrasion refers more to physical abrasions.Corneal ulcers are extremely painful due to nerve exposure, and can cause tearing, squinting, and vision loss of the eye.