Separation of the Inner Lining of the Eye in Dogs

The retina sits against the back wall of the eye. When your dog sees something, that image is focused by the cornea and the lens onto the retina, much like a projector will focus an image on a movie screen. The retina of the eye can become detached from the underlying retinal pigment epithelium (RPE) for many reasons, ranging from genetic predisposition to physical trauma. Retinal detachment can affect one or both eyes, and can involve full or partial detachment. Although partial detachment can sometimes be treated with medication or surgery, full detachment of the retina generally causes blindness in the affected eye.

A retinal detachment is a condition in which the inner lining of the eye, the retina, separates from the underlying structure. This is a serious condition.

Symptoms of retinal detachment can occur in one or both eyes. Depending on the cause of the detachment, onset could be sudden or may take several days to manifest. Symptoms can be nearly indistinguishable from the symptoms of retinal degeneration, which is the death of the cells of the retina, rather than separation.

• Acute onset blindness
• Asymmetrical pupils
• Bloodshot eyes
• Dilated pupils
• Hemorrhage of the eye
• Impaired day vision (hemeralopia)
• Impaired night vision (nyctalopia)
• Ocular discharge 
• Progressive vision loss
• Pupils nonresponsive to light
• Shiny reflection of the eyes, may be greenish

Types 

The retinal detachment will be classified as either macula off, meaning that the macula (the pigmented center of the retina) is fully detached or macula on, meaning that it has not yet fully detached.

• Rhegmatogenous is a tear or break in the retina leads to the accumulation of fluid, causing a detachment of the retina from the retinal pigment epithelium or RPE
• Non-rhegmatogenous is a tear or break that is not complete
• Exudative is damage to the underlying RPE causes fluid to collect underneath the retina, which then pushes it away from the RPE
• Tractional is when the vitreous of the eye contracts, pulling the retina away from the underlying RPE without causing any breaks or tears

There are many factors that can cause a retina to detach from the RPE in your dog’s eye. They could include:

• Eye infections which can be viral, bacterial or fungal
• Genetic predisposition (Australian Shepherd, Bedlington Terrier, Bichon Frise, Border Collie, Cocker Spaniel, Collie, English Springer Spaniel, Labrador Retriever, Miniature Poodle, Miniature Schnauzer, Samoyed, Shetland Sheepdog, Shih Tzu are prone)
• Glaucoma and other degenerative diseases
• High blood pressure
• Hyperviscosity syndrome (a disorder in which the blood becomes too thick, causing small blood vessels in the eyes to rupture)
• Inflammation of the eye
• Injury to the eye
• Ocular surgery
• Poisoning
• Poor environment during fetal development
• Tumors

Your veterinarian will get your dog’s medical history and complete a physical examination, paying special attention to the eyes. A complete blood count, biochemistry profile, and urinalysis will be done to check for any underlying causes such as undiagnosed infections, hormonal imbalances or toxins. An x-ray may also be recommended in some circumstances. Most general practice veterinarians will refer you to a veterinary ophthalmologist at this point in the diagnostic procedure. 

Veterinary ophthalmologists have the proper diagnostic equipment to run further tests, and will examine the retina by direct or indirect ophthalmoscopy. Pupil dilation is usually recommended for this test, but there are rare circumstances that make dilation inadvisable. Specialized ocular ultrasounds can also give the eye specialist better information on damage to the structure of the eye or eyes. If the retina is removed from the eye due to blindness or pain a microscopic evaluation of the eye tissue samples may give additional information about the origin of the disorder.

The prognosis of visual preservation will depend somewhat on the underlying cause of the detachment as well as the severity. It is important to see the ophthalmologist as soon as possible as there are some medical and surgical treatments that become less feasible with time. 

If the retina is fully detached it is rare for the patient to recover vision in the affected eye or eyes. Dogs usually adjust well to partial and even full vision loss with minimal physical or psychological distress. Your veterinarian may recommend removing the detached retina from the eye completely as leaving it in the eye causes an increased possibility of infection or glaucoma.

 If the retina is only partially displaced there are some methods that can help restore vision to the eye. Retinal reattachment surgery will be indicated in cases of breed disposition, physical trauma or if a tear is present. This disorder can often be reversed by addressing the underlying cause, however. Medications to treat the eye and underlying conditions may be given orally or topically, and in some cases even injected directly into the eye. Reversal is often seen in cases such as infection or hypertension with these treatments as well as possible dietary changes.

If surgery was required, you will want to keep your pet in a calm and quiet environment. Make sure that you complete all medications given by your veterinarian, even if visible symptoms disappear. This helps ensure that no reoccurrences of the underlying conditions will follow treatment. If the retinas were detached or had to be removed your dog will be blind in the affected eyes. 

Blindness in one eye usually causes a minimal impact to life quality. You will want to be aware that your dog may startle and snap more easily when approached on its blind side, especially in the first few weeks. If your dog has lost vision in both eyes they can still lead a full and satisfying life with just a few considerations, such as blocking access to potential dangers like stairs or pools and not rearranging objects in their environment without showing them the new arrangement.