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Xerophthalmia (from Ancient Greek xērós (ξηρός) meaning "dry" and ophthalmos (οφθαλμός) meaning "eye") is a medical condition in which the eye fails to produce tears. It may be caused by vitamin A deficiency, [ 1 ] which is sometimes used to describe that condition, although there may be other causes.
Vitamin A in the form of retinoic acid is essential to normal epithelial cell functions. Severe vitamin A deficiency, common in infants and young children in southeast Asia causes xerophthalmia characterized by dryness of the conjunctival epithelium and cornea. Untreated, xerophthalmia progresses to corneal ulceration and blindness. [19]
Vitamin A deficiency is the most common cause of blindness in developing countries. The WHO estimated in 1995 that 13.8 million children had some degree of visual loss related to VAD. [ 10 ] Night blindness and its worsened condition, xerophthalmia , are markers of Vitamin A deficiency; collections of keratin in the conjunctiva , known as Bitot ...
Infected cats typically contract conjunctivitis within a 2-5 day incubation period. [12] Clinical signs of infection are hyperaemia of the nictitating membrane (severity varies), blepharospasm, and discharge from the eye. [7] [12] [13] The infection is not deadly, but if left untreated may cause blindness and pain for the cat. [14]
A rare predominantly black cat with odd eyes. The odd-eyed colouring is caused when either the epistatic (recessive) white gene or dominant white (which masks any other colour genes and turns a cat completely solid white) [3] or the white spotting gene (which is the gene responsible for bicolour coats) [4] prevents melanin granules from reaching one eye during development, resulting in a cat ...
Another vision problem, diabetic retinopathy, is the leading cause of blindness in adults and is caused by damage to the retina from high blood sugar levels. What’s more, risk factors for NAION ...
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception.In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. [6]
Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs and, more rarely, cats. Similar to retinitis pigmentosa in humans, [1] it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness.