Cataract in cats and dogs
What is a Cataract?
A cataract is an opacity (cloudy change) of the lens that avoids light to reach the retina. The crystalline (lens) can be compared to a camera, what means that it is used for focus. If the opacity is very small, there is no alteration of the vision. However when the entire lens becomes more cloudy, the image will be reduced to complete vision loss because the images will not reach the retina. Cataracts can develop in one or both eyes and can take a variety of appearances. The rate of progression is hard to predict and can be very slow or rapid, depending on underlying cause and breed.
Which Dogs/Cats are prone to Cataracts?
All dogs of all ages and breeds can develop cataracts, but they are more commonly found in Fox Terriers, American Cocker Spaniels, Havanese, Bichon Frise, Silky Terriers.
Certain cat breeds are more predisposed such as Persians, Birmans, Himalayans and Domestic Short Hairs.
Nuclear Sclerosis or Cataract?
When the geriatric age arrives, the lens will be hard, and the eyes will get a cloudy bluish-gray appearance. This normal change is called Nuclear Sclerosis or Lenticular Sclerosis. The condition is also seen in humans after 40 years old. At this age, people need glasses to read because the lenses are no longer soft enough to change the shape quickly for near vision. Comparing with people, dogs do not have a good near vision even when they are young, so nuclear sclerosis will not interfere with their near vision and will never be an issue for our pets.
On younger age, the lens is clear because the tissue fibres are perfectly organised, as the pet became older, more and more fibres are deposited until this organisation is lost. The capsule of the lens will not allow the expansion, and this compression will reduce the lens transparency and will give it a hard aspect.
The Vet utilises an ophthalmoscope to look deeper into the eye. If he can see all the way until retina, it means the nuclear sclerosis is present, if the retina is wholly or partially blocked, a cataract should be the cause and this also will tell you that your pet cannot see properly at this stage.
What Causes Cataracts?
Cataracts can be inherited (it is in the genes) or acquired. The acquired cataracts result from injuries to the eye such a trauma (cat claw damage or pellet gun) that lead to a rupture of the lens capsule. Or it can be caused by inflammation within the eye (uveitis), internal metabolic diseases that affect the eye, such as diabetes mellitus and age-related cataract like humans do. Most cataracts in dogs and cats are inherited and can occur at any life stage. A high incidence of cataracts in dogs is also often attributed to diabetes.
Are there types of cataracts?
Cataracts are classified by the age of onset (congenital, acquired or juvenile or senile), physical appearance of the cataract (location in the lens), state of development of the cataract (incipient, immature, mature, hyper mature or morgagnian), or cause (traumatic, metabolic, inherited)
How are cataracts treated?
To date, no medical treatment has been proven to prevent, slow the progression or reverse cataracts. Only surgery can restore the vision loss due to cataracts. The operation consists in lens removal and replacement of a plastic or acrylic lens. Cataract surgery has a good success rate, but a few additional tests are needed before deciding whether your pet is a good surgical candidate. One off the most determinating test involves the retina test. The retina is the structure at the back of the eye in charge to send images to the brain. If the retina is damaged, removing cataracts will not improve the pet’s vision.
See videos cataracts surgical procedure
What if cataract surgery is not done?
Most dogs blinded by cataracts can live perfectly if they live in a safe and stable environment and their eyes are not painful. However, sometimes they can develop a reactive inflammation inside the eye (Lens-induced uveitis) that must be medically treated. Otherwise, this condition will result in complications such as glaucoma (increased intraocular pressure), which can cause optic nerve damage.
The lens luxation is another problem related with untreated cataract. This also will lead to a glaucoma due to a blockage of natural fluid drainage. Glaucoma is a very painful condition showing in the form of a headache (sleepy and grumpy dog) and by the time most of the owners will only notice it when is too late for the pet. The destruction of the optic nerve has then already occurred causing a definitive blindness. At this stage, surgery is required to remove the eye, to allow the pet a painless continuation of his life, as glaucoma, as said, is very painful!
Can the cataract come back after surgery?
No, because all the lens fibres will be removed during the surgery. An uncommon problem that sometimes can occur after cataracts surgery is the progressive scarring of the lens capsule what results in some cloudiness and visual disturbances.
How Can I help to Preserve my dog´s Vision?
Normally cataracts cannot be prevented. However, there are some steps to reduce a vision lost:
Examine your pet´s eyes regularly
Take your pet to the vet if his eyes are red, cloudy, enlarged or you suspect he is having vision trouble.
Do not forget that:
Pets can develop both sclerosis and cataract,
Pets can see well if the cataracts are smaller or if only one eye is blind due a cataract.
In case of severe cataracts, they can develop a “memory map” in their familiar environment, so moving around your furniture will make life difficult for your dog. .