The eye consists of various elements among which:
- the retina, a kind of "screen" that lines the bottom of the eye and receives the images
- and the lens, a lens that ensures the convergence of light rays on the retina.
The cataract corresponds to an opacification of the lens, normally perfectly transparent. This condition is common in dogs.
The symptoms associated with cataract are directly related to loss of transparency of the lens:
Initially, only a careful examination of the eye of the animal allows to observe a slight white, bluish reflection. No visual impairment is noticed.
In more advanced cases, the lens becomes more and more opaque, until it becomes totally white. The vision of the animal gradually decreases until total blindness. The owner notices that his dog begins to bump regularly on obstacles placed on his way, that it remains prostrate ... Some animals even seem to become aggressive (the blinded dog does not see, in fact, more people approaching Of him and can respond sharply, surprised when it is touched).
Various complications can be associated with cataracts:
- Dislocation of the lens: the lens detaches from the suspensory ligament which usually holds it in place and tilts forward or backward
- Glaucoma (pathological increase in intraocular pressure)
- A uveitis (inflammation of the internal structures of the eye)
Origin of cataract
The appearance of a cataract can have various causes:
These are the most common causes of this condition. The lens may then be normal at birth but a genetically programmed cataract will inevitably develop.
This condition appears in young dogs and some breeds are predisposed:
American Cocker Spaniel (age between 2 and 5 years), Poodle (between 2 and 3 years old), Husky, Labrador, Beagle, Bobtail ...
The stage of development of this form of cataract may vary from eye to eye.
Related to aging or senile cataracts:
As the name suggests, it concerns elderly animals (from 8 years in dogs, 12 years in cats)
With age, the lens gradually loses its suppleness and transparency, resulting in a progressive loss of vision. This type of cataract mainly affects dogs. It affects both eyes and evolves very slowly (over several months or even years)
Associated with diabetes:
The excess glucose associated with diabetes leads to disturbances in the metabolism of carbohydrates, which are themselves favorable to the appearance of a cataract in 2 diabetic dogs in 3.
The condition is then bilateral and sometimes very rapid. It can give rise to a significant secondary inflammation of the internal structures of the eye (phacolytic uveitis)
An abnormality occurs during the development of the embryo in the belly of its mother and the child is born with the cataract. This can then be associated with other malformations.
Medicinal or toxic
Following a trauma
In this case, only one eye is reached
Secondary to inflammation:
Uveitis (inflammation of the internal structures of the eye) can cause the appearance of a cataract. This phenomenon is common in cats.
Cataract is an irreversible pathology:
In the early stages of development, drug therapy can be put in place to slow the aging of the lens.
In the more advanced stages, with a significant visual loss, only the surgery allows the animal to recover a correct vision.
- The procedure consists in the removal of the cataract lens (the envelope containing it is partially left in place) thus allowing the passage of light rays back to the retina.
As the lens is not innervated, the operation is not very painful.
- In some cases, the installation of an artificial implant, which will replace the "natural" lens that is the crystalline lens, can be proposed.
- The surgery allows the operated animal to recover the vision in a few days, which is very interesting especially for young animals in which the cataract evolved very quickly and who lost the sight very brutally (for example in cataract hereditary Or diabetic)
- Several eye drops will have to be instilled in the eye operated during the two months following the intervention and regular checks will be carried out by the veterinarian.
However, surgery is only possible for animals in which the other structures of the eye are perfectly intact.
Before any intervention, your veterinarian will:
- An assessment to ensure that the animal is able to undergo general anesthesia (control of cardiac, renal, etc.)
- Electroretinographic examination:
This examination, carried out under general anesthesia, makes it possible to check whether the retina of the animal is still functional or not.
Indeed, any surgery of the lens is perfectly useless if the retina that receives the images and transmits them to the brain via the optic nerve no longer plays its role.
- A complete ophthalmological examination:
Any inflammation of the other structures of the eye will be sought because it contra-indicates intervention on the cataract lens.
Thus, the presence of glaucoma or uveitis (which, as we mentioned above, may be secondary to cataract) prevents surgery, at least in the immediate future.
Cataract is a very common condition in our pets, especially in dogs.
Stages associated with severe visual impairment can be treated surgically, with current interventions with excellent results when any contraindications to surgery have been previously ruled out. These results are even better when the surgery is performed early. Do not hesitate to inform your veterinarian of any abnormalities you may notice in the eyes of your companion.