At DWR Veterinary Specialists, our Ophthalmologists routinely accept referrals from vets, of pets who have suddenly lost their vision to a greater or lesser extent.
In many cases, the pet suffers from a disease for which there is no cure or straightforward treatment and they become visually impaired or irreversibly blind.
The following information will give you more details on the causes of blindness. We also have a page dedicated to some of our brave blind patients.
Causes of blindness
There are many diseases that cause blindness in dogs and cats; some of which may be treatable, such as cataract that you can read more about here, and others such as retinal diseases are untreatable. Some diseases even require the removal of one or both eyes (enucleation) due to the pain it causes the pet, such as end stage glaucoma (high pressure in the eye).
Some of these diseases occur with rapid onset, like Sudden Acquired Retinal Degeneration Syndrome (SARDS), glaucoma or optic neuritis, whereas others cause a slow and gradual loss of vision, as in Progressive Retinal Atrophy (PRT).
- Ocular tumours can affect intraocular (e.g. iris) and extraocular tissue (e.g. conjunctiva, eyelids).
- Cataracts are opacities (cloudy areas) of the part of the eye called the lens. They can affect a small area of the lens (called an incipient or immature cataract) or the majority of the lens (a mature cataract). The latter can cause visual impairment/blindness as the animal cannot see through them.
- Uveitis is inflammation of the middle layer of the eye, called the uvea or uveal tract. It can cause eye pain and changes to vision.
- Glaucoma is a neurodegenerative disease that can affect one or both eyes and occurs when there is increased intraocular pressure inside the eye that damages the retina, which is the structure at the back of the eye and the optic nerve, resulting in blindness.
- Sudden Acquired Retinal Degeneration Syndrome (SARDS) can affect a dog’s retina and leads to sudden and irreversible blindness. The disease is incurable, and the reasons for it are poorly understood, but autoimmune and neuroendocrine mechanisms are thought to be involved.
- Progressive Retinal Atrophy (PRA) is a group of inherited diseases affecting many breeds of dogs and cats, leading to progressive incurable degeneration of the retina. Initially, it shows as partial vision loss (night blindness) and later progresses to total irreversible blindness. In addition, as the retina degenerates, it releases substances that can cause cataract formation.
- Retinal detachment describes a situation when a thin layer of tissue (the neuroretina) at the back of the eye pulls away from the layer of blood vessels that provides it with oxygen and nutrients. It can affect dogs and cats and leads to partial or total blindness.
- Optic neuritis is inflammation of the optic nerve affecting one or both eyes and leads to sudden onset of blindness. The optic nerve can be seen in the retina as an oval/triangular disc which connects to the brain. As a result of this connection, diseases of the brain can cause inflammation of the optic nerve and the retina.
Further reading:
Bedard, K. M., Myrna, K. E., & Diehl, K. A. Preliminary evaluation of effect of two visual aid devices on navigation in blind dogs. Journal of Small Animal Practice. 2020. doi:10.1111/jsap.13120
Hamzianpour et al. Bilateral enucleation in dogs: A review of owner perceptions and satisfaction. Veterinary Ophthalmology, 2018. doi: 10.1111/vop.12623