At a glance
- Retinal detachment
- Dry eye
- Corneal ulcer
Cats are susceptible to several eye problems, which have the potential to impact on their vision (either short-term or permanently). Some eye conditions are due to an underlying (and sometimes undiagnosed) medical condition. All eye (ocular) changes should be investigated by a veterinarian as soon as possible.
Image courtesy of Kirsten
Uveitis is an inflammation of the uvea, the pigmented layer that lies between the inner retina and the outer fibrous layer composed of the sclera and cornea. It is one of the most common eye disorders in cats and can be potentially very serious.
There are many possible causes of uveitis in cats which include immune-mediated disorders, diabetes, metabolic disorders, cancer, trauma, infection (viral, bacterial, fungal or parasitic), high blood pressure and idiopathic (no known cause)
- Pain (squinting, sensitivity to light, excessive watering, third eyelid elevation)
- Swelling of the eyeball
- Changes to the iris
- Abnormal pupil shape
- Eye discharge
- Dull or cloudy appearance to the front of the eye
- Inflammation can cause the eye to become softer (hypotonic)
The goal of treatment is to address the underlying cause as well as relieve symptoms.
- Topical anti-inflammatory drugs to reduce inflammation.
- Topical atropine to dilate (enlarge) the pupils, this helps to reduce pain and stops the inflamed iris sticking to the pupil.
- Analgesics (pain relief).
Also known as hard eye, glaucoma is an increase in the intraocular pressure (IOP), leading to damage to the optic nerve, which connects the eye to the brain. Any damage can cause partial or full blindness.
Glaucoma is often secondary to uveitis (above), other causes include lens subluxation (displacement of the lens), trauma, diabetes, infection, advanced cataracts, and eye tumours.
- Eye enlargement
- Blepharospasm (abnormal contraction of the eyelid muscles)
- Dilated (enlarged) pupil(s)
- Vision loss
- Topical medications to increase fluid drainage and reduce aqueous humour production.
- Steroids: To reduce inflammation.
- Cryosurgery: To freeze a portion of the ciliary body which reduces the production of aqueous humour.
- Treat the underlying cause, if secondary.
If treatment fails to bring down the IOP, it will be necessary to remove the eye.
Retinal detachment is where the retina, the layer of light-sensitive tissue at the back of the eye detaches or pulls away from the underlying layer of blood vessels.
The most common cause is hypertension (high blood pressure), other causes include blood clotting disorders, diabetes, kidney disease, glaucoma, hyperviscosity syndrome, exposure to toxins, uveitis cataracts and lens luxations.
Retinal detachment isn’t painful, and it is quite easy for the condition to go unnoticed. It may occur in one (unilateral) or both eyes (bilateral). When both eyes are affected, it is generally due to an underlying systemic disease.
- Sudden blindness or reduced vision, the cat is bumping into furniture or walls
- Dilated pupils which don’t respond when a light is shone into them
- In some cases, hemorrhage in the front of the eye may be seen
The goal of treatment is to address the underlying issue as well as repair the retina if possible.
- Cryopexy is a procedure in which the ophthalmologist uses extreme cold to freeze the retina around the tear. This causes the area to swell and forms scar tissue when it heals. It is this scar tissue that seals the retina to the wall of the eye.
- Scleral buckle surgery: The surgeon places a piece of silicone to the sclera (the white portion of the eye) to push the sclera towards the break or tear in the retina, the fluid is drained, and the tear is frozen during this process.
- Pneumatic retinopexy: The surgeon injects an air or gas bubble into the centre of your eye, to push the retina back in place. The tear is then lasered or frozen to seal it up.
- Vitrectomy: The vitreous is removed from the eye and replaced with a gas bubble which pushes the retina back in place against the wall of the eye keeps allowing it to heal. The tear is then repaired by cryosurgery or laser.
The role of the lens role is to focus light onto the retina. It is predominantly made up of water and proteins in layers like an onion. A cataract is a clouding/opacity of the lens which occurs when protein within the lens clumps together.
The amount of light which reaches the retina reduces in cats with cataracts. Similar to the view from a frosted window. Over time, as the cloudiness increases, the cat’s vision deteriorates.
The most common causes are due to the natural aging process. However, trauma, inflammation, electric shock, metabolic disorders, poor nutrition, certain drugs, and toxins can all lead to the formation of cataracts.
- Blue/grey cloudy appearance in the pupil(s) of the eye.
- Affected cats may bump into furniture or be more reluctant to explore as their vision declines.
- Phacoemulsification – Surgery to remove the lens and replace it with an artificial one.
- Extracapsular lens extraction – Surgical removal of the entire lens if it is too solid to be break up, or the practice doesn’t have the necessary equipment for phacoemulsification.
In some cases, the cat may not be a suitable candidate for surgery, anti-inflammatory and antibiotic drops can relieve inflammation.
A corneal ulcer is an open sore of the cornea, which is the transparent dome-shaped layer covering the front of the eye.
Scratches, which are common in young cats can damage the outer layer of the cornea. Cells quickly repair this damage.
Erosion of the cornea, typically involving more than one layer is known as a corneal ulcer or ulcerative keratitis. It can occur as a result of injury or trauma (such as rubbing an itchy eye), infection (such as fungal infection, herpes or calicivirus), chemicals, damage due to structural abnormalities such as entropion, dry eye (lack of tear production) and foreign body. Secondary bacterial infection can occur once the cornea has become damaged, further complicating the problem.
- Sensitivity to light
- Cloudiness of the cornea
- Excessive watering of the eye
- Eyelid spasms (blepharospasm)
- Atropine to dilate the pupil and relieve pain as spasms of the ciliary muscle (which controls the dilation and constriction of the pupil) cause pain in the already damaged cornea. Unfortunately, as the pupil is dilated, the eye becomes more sensitive to light; therefore it is important to provide the cat with a dark room to retreat to if necessary.
- Severe corneal ulcers will necessitate the eye be protected while the ulcer heals. This usually involves suturing the eyelid shut for several days which is medically known as a tarsorrhaphy.
Dry eye syndrome is a condition characterised by insufficient watery tears reaching the surface of the eye which leads to dryness of the cornea and the conjunctiva. As a result, they become irritated and inflamed due to the lack of lubrication and moisture.
Herpesvirus is the most common cause of dry eye in cats. Other causes include trauma, immune-mediated inflammation or destruction of the tear glands, inflammation of the eyelid, certain drugs, damage to the facial nerve which activates the tear glands, removal of the third eye to treat cherry eye, congenital.
- Excessive blinking
- Thick, stringy mucoid discharge particularly around the rim of the eyes
- Painful red eyes
- Reluctance to open the eyes
- Swollen eyelids
- Dry, dull and opaque appearance to the cornea
- Sensitivity to light (photophobia)
The goal of treatment is to increase tear production and replace tears as well as addressing the underlying condition where necessary.
- Cyclosporine is an immune modulating medication which can suppress immune system inflammation of the tear glands.
- Artificial tears three times a day to keep the eye moist and lubricated.
- Antibiotics to treat secondary bacterial infections.
- Topical corticosteroids to treat eye inflammation.
- Cats who don’t respond to treatment may require parotid (salivary) duct transposition surgery. This involves moving the parotid duct which is located in on either side of the cheeks up towards the eyes so they can act as additional tear ducts. Saliva and tears are very similar in composition. While this surgery is usually successful, eye drops may still be required.
Also known as pinkeye, conjunctivitis is a common eye disease characterised by inflammation and pinkness of the conjunctiva, the pink membrane which covers the front of the eyeball and the inside of the eyelids. It can affect one eye (unilateral) or both eyes (bilateral) and covers a broad range of possible conditions.
The most common causes include feline herpesvirus, chlamydophilia, coronavirus, and mycoplasma.
- Ocular (eye) discharge
- Red and swollen conjunctiva
- Meaty appearance to the eyes
- Pawing and rubbing at the eye
- Third eye protrusion
Mild cases of conjunctivitis may only require flushing of the eye with a saline solution. Find and treat the underlying cause as well as conjunctivitis.
- Eye irrigations and warm saline soak.
- Anti-inflammatory eye drops.
- Antibiotic eye ointment or systemic antibiotics.
- Topical or systemic anti-viral medications such as Famciclovir.
- L-Lysine for cats with herpesvirus.
- Artificial tears.
- Supportive care.
Blepharitis is an inflammation of the eyelid margins and surrounding skin and in some cases, the Meibomian glands, which are tiny glands on the eyelid margin which secrete an oily substance to keep tears within the eye.
There are several causes which include parasites, infection (viral, bacterial, fungal), eyelid abnormalities, allergies, immune-mediated, trauma, irritants, inflammation and unknown (idiopathic).
- Eye discharge which may contain pus, mucus or watery discharge
- Irritated, watery eyes
- Eyelid redness (hyperemia)
- Inflammation of the eye margins
- Thickening of the eyelids
- Hair loss
- Pawing the eyes due to irritation
- Sensitivity to light (photophobia)
- Inflammation of the cornea
- Squinting or spasmodic blinking (blepharospasm)
The goal of treatment is to address the underlying cause, where possible, which can include the following:
- Corticosteroids to reduce inflammation.
- Topical or oral antibiotics.
- Antiviral eye drops.
- Anti-fungal medications such as itraconazole or ketoconazole.
- Surgery to correct eyelid abnormalities or tumours.
- Immunosuppressive therapy for cats with pemphigus.