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Cataracts in Dogs

What is a Cataract?
What is not a Cataract?
Why did my dog develop a Cataract?
How are Cataracts treated?
How well will my dog see after Cataract surgery?
Why is Cataract surgery so expensive?
What if Cataract surgery is not done?
What is involved in having Cataract surgery performed on my dog?
What are the risks involved with Cataract surgery?

What is a Cataract?

Mature Cataract Immature Cataract
Like a camera, eyes have a clear lens inside them that is used for focusing. A cataract is any opacity within a lens. The opacity can be very small (incipient cataract) and not interfere with vision. It can involve more of the lens (immature cataract) and cause blurred vision. Eventually, the entire lens can become cloudy, and all functional vision lost. This is called a mature cataract.



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What is not a cataract?

Normal geriatric dog eye,
with normal Nuclear Sclerosis
All geriatric dogs develop a hardening of the lens (Nuclear Sclerosis) that causes the lens to have a greyish appearance.

This is not a cataract, and does not usually interfere with vision.

The photo to the right shows a normal geriatric dog eye, affected by normal Nuclear Sclerosis.

Why did my dog develop a Cataract?

  • Most cataracts in dogs are inherited. The cataract may develop rapidly over weeks, or slowly over years, in one or both eyes.
  • Like humans, dogs also develop cataracts with age (often after 8 years of life).
  • Cataracts can also develop in dogs with diabetes mellitus or in orphan puppies on an artificial milk replacer diet.

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How are Cataracts treated?

Once a lens has developed a cataract, there is no known method to make the lens clear again. Immature and mature cataracts can be treated by surgically removing them.
Canine Intraocular Lens (IOL) and a Penny

The procedures and equipment used to remove cataracts in dogs are the same as those used in humans. A small incision is made in the eye and a hole is made in the capsular bag that holds the lens. Phacoemulsification is then performed, in which a special probe ultrasonically emulsifies and removes the cataract. After the entire lens is removed, an artificial replacement lens, called an intraocular lens or IOL, is placed in the bag. The eye is closed with extremely small sutures. Because even the slightest damage to structures in the canine eye can have disastrous effects, the surgery is performed under high magnification using an operating microscope. If both eyes are affected, usually both eyes are operated on at the same time.

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How well will my dog see after Cataract surgery?

After successful cataract surgery dogs see close to normal. However, we cannot give dogs perfect vision. This is because only a handful of different IOLs are available for dogs and an exact replacement of the original lens is not possible. Furthermore, dogs have more inflammation in their eyes after surgery than humans and therefore have more scarring. This scarring does slightly decrease vision. Most owners notice a tremendous increase in their pet's vision after cataract surgery, but they can still detect certain visual difficulties.

After surgery, cataracts cannot recur. However, some dogs can have decreased vision years after cataract surgery due to formed scar tissue, glaucoma, or retinal detachment. In rare instances, placement of an IOL is not possible. These dogs still see better, but are more far-sighted and objects are still out of focus. The cornea does two thirds of the focusing of the eye, so vision is still present but not perfect if the lens (which does one third of the focusing) cannot be replaced.

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Why is Cataract surgery so expensive?

Cataract surgery is expensive because it requires specialized equipment and training. The instruments and equiptment used for cataract surgery in dogs are the same type used for cataract surgery in people. Furthermore, you are paying for the advanced training of a board-certified veterinary ophthalmologist.

When people have cataract surgery, they usually pay very little for it, because insurance picks up most of the tab. This is not the case in veterinary medicine. The pet owner pays 100% of the cost of health care for their pet.

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What if Cataract surgery is not done?

Immature and mature cataracts cause a serious reactive inflammation inside the eye (Lens Induced Uveitis, or LIU) that must be medically treated, whether or not surgery is performed. Cataract surgery is an elective procedure. If surgery is not performed, lifetime anti-inflammatory eye drops are required, as well as periodic eye re-examinations. LIU can lead to complications such as glaucoma or a detached retina, and LIU decreases the success rate of cataract surgery. There is a best window of time in which to perform surgery. The earlier the cataract can be removed, the better.

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What is involved in having Cataract surgery performed on my dog?

The first step is to have your pet examined by Dr. Terri McCalla at Animal Eye Care to determine if your pet is a good candidate for surgery. A preoperative blood profile, comprehensive physical exam, and assessment of anesthetic level of risk are then performed by your family veterinarian. If your pet "passes" these tests, electroretinography (ERG) and gonioscopy testing is scheduled at our hospital, as inpatient procedures. They are performed under sedation, and cause no discomfort. ERG testing evaluates retinal function, as it is vital that the retina (the "film in the camera") is working, in order to perform cataract surgery. Gonioscopy evaluates the drainage angle of the eye to determine if the eye(s) are at increased genetic risk of developing glaucoma postoperatively. If they are, additional medications will be prescribed and these medications may be administered for your pet's lifetime. Ultrasonography of the eye(s) is also performed at another veterinary hospital. Some patients require ultrasonography and not ERG testing. Gonioscopy is sometime performed on the day of cataract surgery.  

If your pet "passes" the ERG test and/or ultrasound test(s), surgery can be scheduled. The eyes require 3 days of intense medication immediately preceding the surgery day. On the day of surgery, your pet will need to arrive at the hospital early in the morning to receive intensive eye treatment before surgery. The surgery is performed and your pet goes home the same day. Your pet will not have eye patches. Vision usually improves during the first week, but the return of vision sometimes takes up to 2-3 weeks. Most dogs exhibit minimal to no pain after surgery. Your pet will require oral medication and several kinds of eye drops 3 to 4 times a day for the first few weeks after surgery, and on a lesser frequency for several months post surgery. Your pet MUST wear a cone-shaped restraint collar (E collar) the first 2 weeks after surgery to prevent self-trauma to the eyes. We also ask that you bring your pet back for reexaminations at 1 day, 5 to 7 days, 2 to 3 weeks, 6 weeks, and 3-4 months post surgery, and every 6-12 months thereafter. This reexamination schedule may change if there are post-operative complications.

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What are the risks involved with Cataract surgery?

Cataract surgery is a highly successful procedure, but there are risks. Chances of the pet having improved vision after surgery are high for most patients (90%-95%). But 5% to 10% of dogs will not regain good vision due to complications, and may actually be permanently blind in one or both of the operated eyes.
 

  • Scar tissue. All dogs develop some intraocular scar tissue. Excessive scar tissue will limit vision.
  • Glaucoma. Glaucoma (increase in eye pressure) occurs in 30% of all dogs who have cataract surgery, usually within the first 24 hours after surgery. Most of these pressure increases are temporary and quickly resolve with treatment. Glaucoma not only can cause complete vision loss, but also may require the need for additional medications or surgery. It can be painful and cause LOSS OF THE EYE if uncontrolled.
  • Retinal detachment. While re-attachment is sometimes possible, the success rate is low and this complication usually results in complete vision loss.
  • Intraocular Infection. While it is rare, it can cause LOSS OF THE EYE (i.e. surgical removal of the eye) as well as complete vision loss.

Therefore, your pet has these risks if Cataract surgery is performed:

  • Development of a complication. This could result in poor to no vision, or in the most severe case surgical removal of the eye (which is rare).
  • General anesthesia. Anesthesia safety has progressed tremendously during the last 5 years. However, even healthy pets CAN DIE UNDER GENERAL ANESTHESIA. We take anesthesia seriously and use the safest medications at Animal Eye Care. All pets are monitored extensively by our surgical staff. All pets receive electronically assisted ventilation and monitoring of their blood oxygenation, carbon dioxide levels, respiration, temperature, heart function, and blood pressure. See Anesthesia Section.

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