Is my pet a good candidate for cataract surgery?
Cataract surgery is an involved and intricate surgery. We need to make sure that your pet is healthy and is free of any problems that might interfere with the success of cataract surgery. In some older dogs we may recommend that your local veterinarian decided whether your pet requires a physical examination and preoperative blood & urine tests, and in some cases chest x-rays and heart examination.
Age alone is not a deterrent to cataract surgery. With the use of modern anaesthetic agents cataract surgery has been successfully performed on dogs and cats as old as 19. One concern with older dogs is that their retinas may also have age related degeneration. In some older dogs the surgery goes well, the eye is clear, the retina is healthy on ophthalmoscopy, but the vision is poor, and we suspect poor brain function in these cases. In some cases these older dogs can be treated with new drugs that help with senility.
Diabetic dogs make excellent candidates for cataract removal. The increased sugar levels in the lens make the cataract softer and easier to remove with the new technique of phacofragmentation. Diabetic patients can have problems as their wound healing is slower and they are more prone to infection. This is overcome by using more sutures to close the wound than we normally use, and by giving postoperative antibiotic tablets.
Cases in which there has been pre-existing reaction against the cataract (lens induced uveitis) tend to have poorer success rates. This reaction will increase the risk of more inflammation after surgery, glaucoma, retinal detachment, bleeding and cloudiness in the eye. We will assess your animal’s eye so we can give you an indication as to the expected prognosis.
When is the best time to operate?
In the past cataract surgery was usually delayed until the cataract had matured and the patient had become totally blind. We now know that surgery is considerably more successful if the cataract is removed before it matures. We now decide to remove the cataract if it is likely to progress. This can usually be predicted by considering the animal’s age, breed, and the size and location of the cataract. In some cases the most predictable thing about cataracts is that they are unpredictable.
Caption: Cataract Machine with instruments
Allowing the cataract to grow and mature will reduce the success rate for a number of reasons. Firstly more mature cataracts are more likely to develop uveitis (inflammation) which can lower the success rate by as much as 20 to 30%. Secondly more mature cataracts can cause vitreous degeneration which may lead to cloudiness in the jelly of the eye. Thirdly the risk of retinal detachment is increased. Fourthly the capsule which holds the lens can become cloudy and opaque.