A cataract is any opacity within the lens of the eye. The lens is a disc-shaped structure that is suspended in the eye by tiny ligaments behind the iris (the coloured part of the eye). It is normally clear to allow light to enter the eye, and it helps to focus that light on the retina. The lens is made up of highly organized cells called lens fibers and is covered by a thin clear capsule that is about the consistency of cellophane.
Cataracts occur when there is damage to the lens fibers. Cataracts may come in many shapes and sizes. They can be small and may not significantly interfere with vision, or they may take up a larger portion of the lens causing obstruction of the light entering the eye and, therefore, blindness.
Cataracts may progress through several different stages. Often proteins will leak from the lens causing inflammation inside the eye. This can cause discomfort and complications such as glaucoma, retinal detachment and degeneration, all of which may cause permanent blindness.Q. What causes a cataract?
In general, cataracts are the result of biochemical damage to the lens fibers which may occur due to several factors:
In order to determine the answer to that question, your dog will need to have his/her eyes evaluated by a veterinary ophthalmologist. We need to determine that your pet will have a reasonable chance of vision after the surgery has been performed. In addition to an eye examination, some diagnostic tests will be required.
Typically an electroretinogram (ERG) is performed to assess the function of the retina, and occasionally, an ultrasound of the eye may be required.
|A dog's eye following cataract surgery|
If your pet is deemed an appropriate candidate for cataract surgery, a date will be set for the surgery. Because cataracts cause inflammation inside the eye, you will need to treat your pet with a topical anti-inflammatory drop twice daily after diagnosis of the cataracts.
Please note that your pet should not be bathed or groomed for several weeks after surgery: plan to have any necessary grooming done before the surgery date. Skin infections and dental disease can increase the risk of infection after cataract surgery. Skin infections must be resolved prior to surgery. If your pet has dental disease, a dental cleaning should be performed at least four weeks prior to the scheduled cataract surgery. It is therefore recommended that you have your pet's skin and teeth evaluated by your veterinarian before surgery is even considered.
If your dog is diabetic: Diabetic dogs should be well regulated prior to surgery, and a urinalysis must be done at your veteirnary clinic one week prior to your surgery appointment. This is important as surgery will not be performed if your pet has ketones in the urine or a urinary tract infection. These conditions will require treatment prior to surgery.
Your pet will be examined the day prior to cataract surgery (usually a Monday). Pre-operative bloodwork and an ERG will be performed. If results of these tests are within normal limits, the surgery will be completed the following day. The morning after surgery, your pet will require a re-evaluation.
Therefore, you should expect to visit the WCVM Veterinary Medical Centre on three consecutive days. Your pet will usually not be hospitalized at night and will be allowed to spend the evenings at home (or in the hotel) with you during this period of time.Q. What is phacoemulsification?
Cataract surgery involves removal of the lens fibers. In order to access the lens, an incision is made in the cornea and a round hole is torn in the front of the lens capsule.
A small, pen-like instrument is introduced into the eye and through the hole in the lens capsule. This instrument produces ultrasonic vibrations that break up the lens material (phacoemulsification) as it simultaneously vacuums this material to remove it from the eye.
After the lens fibers are removed, a lens implant may be inserted into the lens capsule. The lens implant is not necessary for vision but significantly improves near vision. At the completion of the procedure, the cornea is then closed with tiny sutures that absorb over the next four weeks.
Following cataract surgery, you will have a lot of work to do to help achieve a good outcome for your pet. For the first three weeks after surgery, a protective Elizabethan collar (cone) must be worn at all times to prevent self-mutilation and accidental ocular trauma. Patients must be severely restricted in their activities and avoid any running, jumping, excess barking or rough-play.
Several different types of eye drops (usually four types) will need to be administered four times daily for the first three weeks and then the frequency of administration will gradually be reduced. Many dogs will remain on anti-inflammatory eye drops once to twice daily for several months following surgery. Some will require them for life.
Q. What's involved in follow-up care?
In most cases your pet will be discharged into your care during the afternoon of surgery. You will be required to return for a follow-up appointment the next day. Further follow-up times will be decided on an individual basis, but the appointments are typically scheduled for the following dates:
Postoperative success rates for vision following canine cataract surgery are about 80 per cent for the first two and a half years. However, regardless of the surgical method used to remove the cataract, several postoperative complications can develop. Some of these complications lead to permanent blindness and ocular pain. In those cases, further surgery will be required to remove the eye or to place an intrascleral prosthesis.
To make an appointment with the veterinary ophthalmologist, you will need a referral from your veterinarian for an assessment. Your veterinarian can complete and send in an ophthalmology referral form after which you may contact us to book an assessment.
Small Animal Clinic:
Large Animal Clinic: