What is a Cataract?
A cataract is an opacity/cloudy change to the lens that blocks light from reaching the retina. Cataracts can develop in one or both eyes and in severe cases, can lead to blindness. Some cataracts may develop very quickly and result in overnight loss of functional vision.
Cataracts can vary greatly in appearance, ranging anywhere from small hazy dots that don't affect vision to complete whitening of the lens. Cataracts often progress to affect larger areas of the lens. However, some cataracts remain the same size and never affect vision. Unfortunately, it is often very difficult to predict if and how quickly a cataract will progress.
What Causes Cataracts?
Cataracts can be inherited as a genetic condition or can occur due to eye injury, infammation inside the eye, retinal disease, internal disease (such as diabetes mellitus) or may simple be attributed to age related changes. On occasion, it is difficult to determine a specific cause for your pet's cataracts.
What Is The Treatment For Cataracts?
To date, no known medical treatment has been proven to slow, prevent or reverse cataract formation. Therefore, the only treatment for cataracts is surgical removal, as is commonly performed in 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 us at Eye Care for Animals to have your pet examined by one of our veterinary ophthalmologists.
As cataracts progress, they are more likely to cause a secondary complication such as glaucoma, inflammation and/or retinal detachment. It is important that your pet's cataract be evaluated early, as an ophthalmologist may be able to prevent such problems from occurring. In addition, as a cataract progresses, the success rate of surgical removal declines. A veterinary ophthalmologist would be able to discuss the specifics regarding your pet's cataracts and overall prognosis for surgery.
Note that not all cataracts require surgery. If your pet’s vision is not significantly impaired, surgery may not be necessary at this time.
What Do We Examine?
We evaluate each eye to determine the size, location, and density of the cataract(s). In addition, we assess the overall health of the eye and search for signs of ocular inflammation, glaucoma, retinal detachments, and other changes that are commonly associated with cataracts. During our exam, we can also estimate the extent of your pet's vision loss.
Often, we are unable to evaluate any structures behind the cataract. In this case, an ERG (Electroretinogram) and ocular ultrasound are usually necessary to help determine the eye(s) candidacy for surgery. Specifically, the ERG determines how well the retina is functioning while the ultrasound allows us to visualize the back half of the eye. Both these tests are non-invasive.
Before surgery, we evaluate each patient’s general health status to help ensure that they can tolerate anesthesia. In so doing, we routinely assess blood work and repeat a physical examination. If these reveal any concerns, we may recommend additional diagnostic testing prior to surgery.
What Does Cataract Surgery Involve?
Cataract surgery is performed on an outpatient basis. We typically ask that you bring your pet in the morning so that they can be appropriately re-evaluated and prepared for surgery. Once your pet has recovered from anesthesia, we will call you towards arranging a pick up time. At the time of pick-up, we will go over medication and recheck instructions in great detail.
We use highly advanced anesthetic agents and monitoring equipment for all our surgeries. In addition, one of our experienced technicians will be closely monitoring your pet throughout the procedure.
The surgery involves placing a pen-shaped instrument into the eye that uses ultrasound energy to breakdown the lens fibers, which it then vacuums out of the eye. Once the lens is removed, an artificial lens implant, designed specifically for a dog, cat or horse is implanted into the remaining lens capsule/shell. The required incision site is generally less than 1/2 of a centimeter and is closed with hair-like sutures which dissolve. Following surgery, we often partially suture your pet’s eyelids for added protection as the eye heals. These sutures are removed 2-3 weeks after surgery. We may also recommend that your pet wear an e-collar to prevent self-trauma as the surgical site heals.
Post-operatively, you will be instructed to administer both topical and oral medications, which will eventually be tapered to a low-level maintenance regimen. The use of these medications is critical to the recovery and success of surgery by helping to prevent infection and control postoperative infammation.
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. However, despite our best efforts to prevent them, several potential complications can and do arise in approximately 5 - 10% of patients. These potential complications include the following:
- Break down of the tissue or suture (incision dehiscence)
- Infections at the surgical site, which may extend to other internal and/or external areas of the eye (intraocular/extraocular infections)
- Corneal ulcerations
- Corneal scarring, vascularization, or mineralization
- Inflammation inside the eye (uveitis)
- Glaucoma (elevated intraocular pressure)
- Retinal detachment or degeneration
- Ocular or orbital pain, secondary to uveitis, glaucoma or infection
- Eyelid rubbing
- Bleeding inside the eye (hyphema)
- Excessive tearing
- Displacement of the intraocular lens implant
- Some of these complications can lead to discomfort and blindness.
What Will My Pet Be Able To See After Surgery?
Occasionally, our patients have improved functional vision by the time you pick them up from surgery. However, some patients may take several days before vision returns. In generally, an artificial lens implant will greatly improve the accuracy with which your pet will see after surgery.
In some cases, we opt not to place an intraocular lens implant. In these dogs, visual images will be slightly larger and less distinct than normal. In addition, they will be unable to focus on nearby objects, which often manifests as having difficulty with depth perception. However, these patients retain functional visional and tend to compensate very quickly.Can The Cataract Come Back After Surgery?
Because we remove all of the lens fibers during surgery, the cataract does not come back. In some cases, progressive scarring of the capsule that once surrounded the lens may result in a recurrence of cloudiness. However, such changes rarely affect functional vision.
If you have any questions about cataracts or are concerned that your pet might have cataracts, please do not hesitate to call us at Eye Care for Animals.
