Cataracts
What is a cataract?
A cataract is an opacity of the lens that prevents light from reaching the retina, which means cataracts lead to vision impairment. Cataracts can develop in one or both eyes and have a variety of causes.
A cataract can take on a variety of appearances. Most owners note a cloudy or white to blue appearance to the eye. The cataract might start as small dots or white lines that progress to include larger areas of the lens or the eye may appear to turn cloudy overnight. The rate of progression is difficult to predict and can vary by underlying cause.
What causes cataracts?
Cataracts can be inherited or acquired. Many dog breeds are known to have cataracts that are inherited – meaning it is in their genes. This is an important consideration for breeding dogs. Acquired cataracts can result from causes such as injury, inflammation, and internal metabolic diseases that affect the eye (such as diabetes mellitus). Dogs also get age-related cataract like humans do. No matter what the cause of cataract, the only definitive treatment is removal.
What is the treatment for cataracts?
To date, no known eye drop or medical treatment has been proven to slow progression, prevent formation or reverse the changes caused by a cataract. Surgical removal of a cataract is the only currently available and effective treatment that can restore vision in animals and humans.
What should you do if you suspect a cataract?
If you suspect that a cataract is forming in one or both of your pet’s eyes, call Eye Care for Animals.
Animals and arrange to have your pet examined by one of our veterinary ophthalmologists.
A complete ocular exam involving all structures of the eye is required to fully evaluate the cataract and determine the prognosis for surgery. If a cataract is not completely filling the lens, we can examine the retina and other parts of the eye with relative ease. If a cataract is complete, we are not able to examine the back of the eye – specifically the retina. A few additional tests are recommended before determining whether your pet is a good candidate for cataract surgery. The earlier we examine a cataract case the sooner we can treat vision threatening inflammation in the eye that often occurs with cataract formation. Thus, the earlier we see your pet the better.
What do we examine?
We evaluate each eye for the extent and density of cataract formation, rapidity of change, presence and severity of ocular inflammation and extent of vision loss. We may recommend additional testing from your primary veterinarian to determine that your pet is in good physical health and if he/she is a good candidate for general anesthesia. Based on these findings, we will make recommendations on whether or not to pursue surgery.
We recommend cataract surgery for those patients whose vision is significantly impaired by cataract progression. It is a common misconception that a cataract must “ripen” or mature before cataract surgery can be performed. This is not the case. In fact, surgery to remove immature cataracts generally carries a post-operative prognosis and decreased chance of post-operative complications. It is important also to remember that cataract removal surgery is an elective procedure. While removing cataracts generally improves the quality of life in pets, many pets have very satisfactory lives with vision impairment. Your pet’s health, your goals, your finances, your availability, and many other factors should be considered before making a decision.
If we recommend surgery in both eyes, we also discuss with you how we will proceed. In general, we recommend cataract surgery on both eyes simultaneously to reduce anesthetic risk to your pet and improve post-operative outcomes. It also tends to be more cost efficient. There are occasions when we might opt to stage the surgeries, operating first on the most impaired eye. Surgical recommendations are made on a pet by pet basis. The final factor in determining whether your pet is a candidate for cataract removal surgery involves retinal testing. The retina is the structure at the back of the eye that transmits images to the brain. If the retina is not in good condition, removing cataracts will not improve your pet’s vision. The retina is tested in two ways: functionally and structurally. To test the retina’s function, we perform a non-invasive procedure called an electroretinogram (ERG). If the ERG is normal, we perform an ocular ultrasound to make sure there are no holes, tears, or detachments of the retina. These tests generally required your pet to be with us for about half a day. These procedures are not painful, but mild sedation may be used if your pet is nervous. We recommend having these tests performed within 2 to 3 weeks before surgery.
What does cataract surgery involve?
Cataract surgery is performed on an outpatient basis after an initial preoperative period (three to five days) when a few medications are administered at home to prepare the eyes. Your pet will be admitted to the hospital on the morning of the surgery to allow time for IV catheter placement and administration of more eye drops at frequent intervals. Your pet should not be fed breakfast on the morning of surgery – UNLESS he/she is a diabetic. Diabetic pets should get ½ the normal breakfast and ½ the normal insulin – unless otherwise specified by one of our doctors.
For cataract (and any other) surgery, we use the most advanced anesthetic agents and monitoring equipment available. During the surgery, our technicians carefully monitor your pet’s respiration, heart rate, and blood pressure. The actual surgical procedure takes approximately 30 to 40 minutes and the general anesthesia typically lasts 45 to 60 minutes. The procedure involves first making a very small incision at the top corner of your pet’s eye. Small surgical instruments are used to remove a small circular portion of the clear lens capsule that surrounds the cataract. Next, we use a state of the art “ultrasonic vacuum” to remove all of the cataractous lens fibers. Once the lens fibers are removed, an artificial lens, designed specifically for dog or cat eyes, is placed into the lens capsule. There are occasions when the artificial lens cannot be placed because the lens capsule is torn or unstable. Even if an artificial lens is not able to be placed, your pet will still have vision after surgery. He or she will be mildly far-sighted but able to see much better than with a cataract. The final step involves closing the surgical incision. The size of the incision in the eye needed for this procedure is generally less than half of a centimeter.
During post-operative and anesthetic recovery, we continue to closely monitor your pet. Usually, patients are ready to be discharged from the hospital approximately two to three hours after surgery. We will call you after your pet has recovered from anesthesia to set up a specific discharge time. To protect your pet’s eyes after surgery, your pet’s eyelids might be partially sutured to serve as a temporary bandage. If so, we remove these eyelid sutures ten to 14 days after surgery. He or she will also need to wear a cone or e-collar.
Postoperatively, we will want to recheck your pet 4 to 6 times in the first couple of months. You will continue to administer topical and/or oral medications, which we gradually taper to a low-level maintenance regimen. The use of these medications is critical to the success of surgery by helping to prevent infection and to control postoperative inflammation.
What are the complications of cataract surgery?
With the advent of new therapeutic drugs and microsurgical techniques, the success rate of cataract surgery has improved dramatically in recent years. On occasion, despite our best efforts to prevent them, complications can arise in approximately 5 -10% of patients. These potential complications include the following:
- Breakdown of the tissue or suture material (incision dehiscence)
- Infections at the surgical site, which may extend to other internal and/or external areas of the eye
- Corneal ulcerations
- Corneal scarring, vascularization, or mineralization
- Inflammation inside the eye (uveitis)
- Glaucoma (elevated intraocular pressure)
- Retinal detachment or degeneration
- Bleeding inside the eye (hyphema)
- Displacement of the intraocular lens implant
Some of these complications can lead to discomfort and blindness, but many of them can be successfully treated and managed with early intervention. Adherence to the post-operative medication and recheck schedule is critical to minimizing risk of complications.
What will my pet be able to see after surgery?
The surgical removal of a vision-impairing cataract can result in a dramatic improvement of functional vision. Some dogs need more time to adjust than others, but most notice their pets are seeing well within 2 weeks after surgery. The implantation of an intraocular lens will bring your pet’s vision back to as close to normal as possible. As previously stated, pets that do not receive intraocular lenses will still have vision, but their near-vision, depth perception, and visual acuity will be reduced but still much better than with cataract. Some owners may not notice this difference unless their dog performed work or tricks requiring high visual acuity prior to cataract formation.
Can the cataract come back after surgery?
No. Because we remove all of the lens fibers during surgery, the cataract cannot come back. In some cases, progressive scarring of the capsule that surrounded the lens may result in some cloudiness and a recurrence of visual disturbances many years from the time of cataract surgery. This is uncommon, but if it does occur in your pet, we can attempt to remove this scar tissue with a non-invasive laser procedure, that may be available at some locations.
