Common Disorders

There are many eye disorders that affect our dogs, and we’ve listed some of the more common ones here. We are not veterinarians, and are offering an overview only, not as a diagnostic tool. Please see your veterinarian if you suspect any of these or other eye disorders in your dog.

This website is not substitute for a veterinarian examination.

Please click here to view a glossary of terms.


Cataracts affect the lens of the eye, causing a film to form. In early stages, it often affects sight very little, and is usually more treatable. As cataracts mature, they cause worsened vision. Often confused with cataracts is a condition called nuclear sclerosis. This is a hardening and greying of the lens in older dogs. This is not a cataract, and does not affect vision. Cataracts can be treated surgically, and often restore sight, especially in early stages. However, not all dogs regain sight from cataracts. If you suspect your dog has cataracts, please see your veterinarian.

More information: Animal Eye Care, petMD, Veterinary Vision


Glaucoma is an increased pressure in the eyes. Fluid within the eye builds up and does not drain properly. Glaucoma causes blindness by damaging the optic nerve and by decreasing blood flow to the retina. This increased pressure can cause pain Glaucoma can be treated by eyedrops or surgically. The type of surgery depends on whether the dog will be able to retain any vision. Unfortunately, often the dog is already blind in the affected eye by the time the glaucoma is detected. Often the other eye is at risk for developing glaucoma, so vets may prescribe eyedrops to delay this from happening.

More information: Veterinary Vision, petMD

Progressive Retinal Atrophy (PRA or PRD)

PRA (also known as PRD) is an inherited disease of the retina, which is a tissue that surrounds the inside of the eyeball and works much like film in a camera. Often the first symptom is their dog becoming “night blind”, or having difficulty seeing in low light. Over time, the pupils become dilated, and owners may notice a glow from the dog’s eyes. The rate of progression varies from dog to dog, but blindness does come eventually. However, PRA is painless.

More information:   Veterinary Vision, Animal Eye Care, petMD

Suddenly Acquired Retinal Degeneration (SARDS)

SARDS is a disease of the retina that causes blindness quickly, within a matter of days to weeks. Owners of dogs who develop SARDS may report noticing an increase in thirst and urination and weight gain in their dog. SARDS may also be associated with Cushing’s disease, which is the production of excess hormones from the pituitary gland that can cause a host of symptoms in dogs. SARDS is not painful. Please look at these links to learn more about SARDS.

  • Helpful tips for dog owners
  • Research Article – SARDS diagnosis strategies and therapy options
  • Report on a study findings examining the role of the immune system in SARDS
  • Additional reading on SARDS

Other Causes


Diabetic dogs can live healthy lives. Unfortunately, a common complication of diabetes in dogs is cataracts (cloudy lenses). In fact, 75% of dogs develop cataracts and blindness in both eyes within one year of being diagnosed with diabetes. The cataracts develop very quickly — sometimes overnight! If untreated, the cataracts cause intraocular inflammation called Lens-Induced Uveitis (LIU) that harms the eyes by causing glaucoma (increased intraocular pressure). If the LIU is uncontrolled and glaucoma develops, cataract surgery might not be possible. Glaucoma causes a chronic headache (similar to a migraine). Once it is apparent that cataracts are forming, it is important to have your pet examined by a veterinary ophthalmologist as soon as possible. For more information, please visit the sites below.

  • Diabetes and eye conditions
  • Managing diabetes in dogs
  • AKC’s article on symptoms and treatment of Diabetes in Dogs

Corneal Ulcer

A corneal ulcer is a break in the outer layer or epithelium of the cornea. Uncomplicated ulcers, although initially painful, should heal in 3 to 4 days with appropriate treatment. Those ulcers that persist longer than this period of time often prove to be complicated ulcers. Please visit the links below to learn more.

Corneal Dystrophy

In most breeds, corneal dystrophy appears as gray-white, crystalline or metallic opacities in the center of the cornea or close to the periphery. These opacities may affect any layer of the cornea, the epithelium (outer layer), the stroma (the thick, middle layer), or the endothelium (the inner layer). The opacities are usually oval or round and are sometimes doughnut-shaped. Please visit the links below to learn more.

  • The different types of corneal dystrophy and treatment options
  • Pet MD’s article on corneal dystrophy

Retinal Dysplasia

Retinal dysplasia is a type of retinal malformation. The word “dysplasia” simply means “a defective development of an organ or structure”. Retinal dysplasia occurs when the 2 primitive layers of the retina do not form together properly. Mild dysplasia manifests as folds in the inner retinal layer. These are called “retinal folds”. In “geographic” retinal dysplasia there are larger areas of defective retinal development. In the severe form of dysplasia, the 2 retinal layers do not come together at all and retinal detachment occurs. Retinal dysplasia is not progressive. It is a congenital defect and animals are born with as severe a condition as they will ever get. Please click here to learn more about the symptoms and treatment of retinal dysplasia .

Dry Eye (KCS)

Keratoconjunctivitis sicca (KCS) or “dry eye” describes the changes in the eye which result from lack of tear production. To understand “dry eye” it is helpful to know how tears help keep the cornea healthy. The cornea is the optically clear portion of the eye that allows entry of light into the eye. Like all living tissue, the cornea requires a supply of oxygen and energy to remain healthy. Oxygen and nutrients are supplied to most tissues by the blood that moves through the area in blood vessels. The healthy cornea has no blood vessels, if it did it wouldn’t be clear, so the oxygen and nutrients are supplied through the three-layered ‘tear film.’ Please click on the links below for additional information.

  • Research article on current treatment methods
  • Today’s Veterinary Practice article on KCS
  • PetMD article
  • Treatment tips for KCS

Cherry Eye

A prolapsed gland of the third eyelid (or “cherry eye”) is thought to be associated with a laxity of a small ligament which holds the gland in a normal position behind the third eyelid. The gland is a tear producing gland, and produces about 30% of the tears, while the main orbital lacrimal gland produces the rest. Dogs that have had the gland of the third eyelid surgically excised have a greater risk of development of a dry eye (KCS) than dogs with intact third eyelid glands. It is thought that should the main orbital lacrimal gland be damaged later in life that there is no “backup” for tear production. Dry eye is a serious eye condition that is difficult to treat, and requires lifelong treatment which may be costly. If the chance of the development of a dry eye can be lessened by tacking the gland back into a normal position so that it stays functional, then this is the most desirable way of handling “cherry eye”.

  • Learn more about cherry eye
  • Treatment options for cherry eye

Lens Luxation

The lens can either become loosened (subluxated) or completely detached (luxated). When the lens completely tears free of its zonular attachments and falls forward into the anterior chamber, we call this an anterior luxation. It is also possible for the lens to luxate posteriorly into the vitreous body. Since lens luxation may cause glaucoma, and since glaucoma may cause lens luxation it is important to determine which disease came first. When lens luxation occurs secondarily to glaucoma, it usually occurs late in the disease once the elevated pressure within the eye has caused the sclera to stretch, and the zonular ligaments to tear. This does not occur until long after vision has been lost. In such a case, attention must be given to resolving the pain with glaucoma. To learn more please visit the links below.

  • VCA’s article on lens luxation
  • Signs and treatment options

Double Merle, Double Dapple, Double Harlequin, Lethal White (Preventable)

Merle is a distinctive color pattern for some breeds, such as Australian Shepherds, Dachshunds, Collies and Shelties, and the double merle genetic defect can be found in any dog with the merle or dapple coat. Double Merles are also called lethal whites (a term used to refer to the more politically correct double merle (MM) gene, or homozygous genetic defect). In other words, when two merle dogs are bred together, a genetic defect will be created in some of the litter, and this defect will cause them to be blind and/or deaf.  The affected puppies in the litter will also be colored mostly or completely white. More information can be found here and here. Please click here to learn how this condition can be prevented.

Horner’s Syndrome

Horner’s syndrome is not uncommon and occurs in dogs, cats, horses and many other species. The symptoms generally include a sunken in eye (enophthalmia) with a small pupil (miosis), a droopy upper eyelid (ptosis) and a prominant third eyelid. Horner’s syndrome must be differentiated from Uveitis which also produces a constricted pupil and a droopy looking eye.

  • VCA’s article on horner’s syndrome in dogs
  • Symptoms, diagnosis, and treatment


Uveitis is a viral infection which can often occur in horses and humans, but rarely in dogs. Uveitis means “inflammation of the uvea”, or the middle layer of the eye. The uvea consists of three structures: the iris, the ciliary body, and the choroid. The iris is the colored structure surrounding the pupil, visible in the front of the eye. The ciliary body is a structure containing muscle and is located behind the iris which focuses the lens. The choroid is a layer containing blood vessels that line the back of the eye and is located between the inner visually sensitive layer, called the retina, and the outer white eye wall, called the sclera. Inflammation occurring in any of these three structures is termed “uveitis”.