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Blindness in animals can be caused be the result of environmental adaptations over time, or due to various conditions of the eyes. [1] Many blind species have been able to adapt, [2] navigate and survive in their environment by relying on their other senses. Some species are born without eyes such as the kauaŹ»i cave wolf spider, olm and the ...
Symptoms include sudden permanent blindness, but may occur more slowly over several days, weeks or months, [3] dilated pupils. Pupillary light reflexes are usually reduced but present; the slow phase mediated by melanopsin in retinal ganglion cells is retained.
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.
Some tests have revealed that myopia in some animals can be improved with eye drops containing zinc, by increasing the activity of superoxide dismutase (SOD). [7] The rhesus monkey's vision amplitude reduction is noticeable in its second decade of life; however the condition does not impede normal functioning.
There are many diseases known to cause ocular or visual changes. Diabetes , for example, is the leading cause of new cases of blindness in those aged 20–74, with ocular manifestations such as diabetic retinopathy and macular edema affecting up to 80% of those who have had the disease for 15 years or more.
This test could eliminate progressive retinal atrophy from the English Shepherd.
Retinal dysplasia is an eye disease affecting the retina of animals and, less commonly, humans. It is usually a nonprogressive disease and can be caused by viral infections, drugs, vitamin A deficiency, or genetic defects. Retinal dysplasia is characterized by folds or rosettes (round clumps) of the retinal tissue.
In 1632, Vopiscus Fortunatus Plempius examined a myopic eye and confirmed that myopia was due to a lengthening of its axial diameter. [157] The idea that myopia was caused by the eye strain involved in reading or doing other work close to the eyes was a consistent theme for several centuries. [101]