Please read this information carefully. If you have any questions or concerns about the procedure, we would be happy to discuss them with you.
What is a cataract?
A cataract is a clouding of the crystalline lens inside the eye. The lens is a clear structure that focuses light onto the back of the eye in the same way that a camera lens focuses light onto a film. A cataract develops when the normally transparent lens becomes cloudy and hard, so that light cannot pass through it, and the eye becomes blind.
What can be done about it?
Surgery can be performed to remove the cataract. The technique used is called phacoemulsification, and is the same treatment as that used for cataracts in people.
A small probe is placed into the eye through a small incision. A window is made in the lens capsule (the lens capsule is a transparent bag that holds the lens in place inside the eye, see diagram) and the cataract is gently broken down and removed via the probe. Because the structures inside the eye are so small, we perform the surgery with the aid of an operating microscope.
Following removal of the cataract, we will usually place an artificial lens (lens implant) inside the lens capsule. An artificial lens allows the eye to focus almost as normal. In some cases, however we will not place an artificial lens. In such cases, the eye is still visual but will not be able to focus quite as well; still, most animals cope extremely well and have good functional vision.
How successful is the operation?
Phacoemulsification success rates are around 85-90%. This is very good, but still means that 10-15% of operations can have complications, which may arise during the surgery or at a later date. Some complications can be successfully treated by long-term eye medication but in a few cases permanent blindness can occur and in very rare instances enucleation (removal of the eye) may be necessary. The most serious complications include bleeding into the eye, inflammation and eye pain, retinal detachment and glaucoma. Usually, however, the cataract surgery is successful and a good degree of vision is restored, which greatly improves the quality of life of the patient. Also remember that without surgery the eye will remain blind and may also develop serious and painful problems such as inflammation and glaucoma, which may preclude surgery at a later date.
Can the cataract form again?
The cataract itself cannot reform as the lens has been completely removed. However a type of scarring can develop within the lens capsule, and may cause reduced vision; this is known as ‘after-cataract’. This is also a common problem in people, and precautions are taken to minimise the risk of ‘after-cataract’. Very occasionally, a second operation is required to remove the scarring.
If I want to go ahead, what is the timescale for the surgery?
We may want to give a course of eye drops for a week or so prior to the operation. Your pet will then be admitted to the hospital the day before the operation is scheduled, so that they get used to the environment, and can receive pre-operative eye drops. The following day the operation is performed under a general anaesthetic. We will often perform an ultrasound scan of the eye and a test called an ERG (which checks that the retina is working) immediately before the operation. The operation itself usually takes around 45-60 minutes per eye. Most patients stay in the hospital for 3-4 nights following surgery so that we can monitor their eyes frequently and apply post-operative eye drops.
What happens after the operation?
A course of tablets (antibiotics and anti-inflammatory/pain-relievers) and eye drops are prescribed for several weeks following the cataract surgery. A typical post-operative treatment plan would be a long course of eye drops (e.g. 5x daily for 2 weeks, then 4x daily for 4 weeks, then 3x daily for 4 weeks, then 2x daily etc) plus tablets twice daily for 4 weeks. This is a guide and treatment regimes may vary. It is vital that the instructions are followed precisely. If treatment is stopped early, irreversible damage to the eye may develop. The animal will need to be handled gently for one to two weeks, and discouraged from vigorous play and exercise. An Elizabethan-style collar may be needed for a week or so. Post-operative check-ups are also required. Again, it is vital that these are performed so that we can check for any complications. Typically, we may need to re-examine a case 1, 2, 4 and 8 weeks post-operatively, then at 3 to 6 monthly intervals if possible. Again, this is a guide, and check-up times will vary between patients. If you have travelled far, then your own vet may be able to perform some of the later check-ups.
Davies Veterinary Specialists, Manor Farm Business Park, Higham Gobion, Herts SG5 3HR 01582 883950
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