What The Retina Does
The thin delicate retina that lines the back of the eye registers images for transmission to the brain. Behind the thin retina is the choroid, a pigmented tissue covered in branches of blood vessels. Also behind the retina is a glistening opaque reflective layer of cells called the tapetum lucidum.The yellow-green colour you see in flash photos of your pet is a reflection of light from these layers. (In our eyes the reflection is of course red.
Inherited Retinal Degeneration In Dogs - Progressive Retinal Atrophy -Pra
This is a common inherited eye condition, recognised in over 90 breeds. Retinal cells die and blood vessels in the choroid shrivel, leading to blindness. The first sign of diminishing sight is usually night blindness. This progresses to lack of confidence jumping down or walking down stairs. Complete blindness is usually inevitable.
Diagnosis and treatment
The disease is diagnosed by ophthalmologic examination. There is no treatment.
As with hereditary cataracts, there are examination schemes to certify that breeding individuals are free from signs of PRA. Even more important is the knowledge that several previous generations are free of late onset PRA. DNA tests are now available.
Both trauma and disease, either acquired or inherited, can cause the retina to detach from its epithelium. Vision is affected but not lost.
Diagnosis and treatment
A detached retina is seen on ophthalmologic examination. Detached retinas can be reattached by laser surgery
Sight Tests And Handling Blindness
A pet that has gradually gone blind may remain perfectly confident on its own, well-memorised territory. As a sight test, slightly rearrange the furniture in one of your rooms, allow your pet in, and with the room darkened watch what happens. Repeat this with the lights on. A completely blind pet will do no better with the lights on than in the darkened room while partly sighted pets are more confident when light is good. Shining a light in your pet's eye may cause the pupil to constrict but that alone does not mean it sees let alone sees well.
How a pet handles blindness varies not only with its own personality but also with its owners. While some people and pets cope just fine, others don't. We have known blind dogs that run confidently with their jogging owners and others with no interest in life once sight has been lost. The decision on how to manage a blind pet is one that only you and your dog, with our help, can answer.