Progressive Retinal Atrophy, also known as retinal pigment epithelial dystrophy (RPED), is part of a group of genetic degenerative eye diseases that affect the retina. Although it is more common in dogs it is also found in cats especially Persians, Abyssinian, some shorthairs and Siamese cats.
The disease causes vision impairment, which eventually leads to blindness. Progressive Retinal Atrophy appears in both male and female cats and is either a dominant or recessive trait (autosomal trait). This disease is similar in nature to Retina Pigmentosa in humans.
In Abyssinian cats there are two forms of the disease, if it is present at birth or shortly thereafter it is a genetic autosomal dominant gene. If it occurs in middle age it is genetic autosomal recessive gene.
What happens is that the retina pigment's epithelium is unable to facilitate a neuron called a photoreceptor, which in turn is then not able to go through the process of phototransduction.
Phototransduction is the process from beginning to end where light enters from the environment and goes through a process to convert that light into what we actually see. The condition leads to degeneration of the photoreceptor, eventually leading to blindness.
It is believed that a vitamin E deficiency may also contribute to the degeneration.
Decreased night vision (Nyctalopia)
Pupils become dilated
Opaque or Cloudy lens
Papillary Light Reflex (reduction of pupil size because of light shining into the eye or an object coming close to the eye)
Visual examinations of the cat whereby black pigmentation can be see around the retina. Electronretinography - measures the electrical activity of the retina, whereby tiny electrodes are placed on the cornea. Fundoscopy - is an instrument that measures the shrinking blood vessels it measures decreased pigmentation of fundus of the eye, which is the interior surface of the eye that houses the retina and other ocular mechanisms. It also examines the tapetum lucidum - a layer behind or within the retina that is responsible for light reflection especially in the evening or dark. It can also inspect an atrophied optic disc (also known as the blind spot).
It is sad to say that there is no cure for Progressive Retinal Atrophy nor is there any method to slow down the disease at present. On a good note, cats are extremely adaptable and can get around quite easily, unless their environment changes. For example things like furniture are suddenly moved around on them. They are not familiar with the new placement and will bump into them or become very timid, not wanting to explore.
Even though in recent years there is a DNA test being perfected to detect Progressive Retinal Atrophy in dogs, no such test is available at this moment for cats.
The best prevention method today for cats is to have them spayed and neutered, that way they are unable to pass on the gene. If your cat develops this disease you should notify the breeder immediately so that the lineage can be traced and flagged for the disease as well.
If your cat has been diagnosed with Progressive Retinal Atrophy know that it can live comfortably to old age providing it does not have any other fatal disease. Just make sure you provide a stable comfortable home and lots of love.