Cataracts are an opacification of the lens in the eye that may cause blindness. They are relatively common in dogs, resulting from various causes, including a genetic/hereditary basis. Pets with hereditary cataracts should not be bred. Improved microsurgical techniques have increased the success rates of restoring vision to affected animals.

Many eye problems are managed by a general veterinarian. However, if the regular veterinarian believes that the patient would benefit by the skills and experience of a specialist, the doctor will refer the patient to a veterinary ophthalmologist for care. 

Some typical problems that are referred to a veterinary ophthalmologist may include: cataracts, glaucoma, retinal diseases, severe injuries, and cancer of the eye. 

What is it?

• The lens is a living ocular tissue that, when healthy, is transparent. A normal lens helps focus light on the retina, a light sensitive nerve tissue located in the back of the eye. A cataract is an abnormality of the lens in which an opacity, or a cloudy change in the tissue, scatters light. Hence, the normal composition of the lens is disrupted and its transparency is lost. If a large portion of the lens becomes a cataract, it prevents formed light from reaching the retina, causing poor vision.
• A cataract can assume a variety of appearances such as small spots, a cracked-ice appearance, a diffuse milky haze, a "pearl-like" sheen, or white streaks. The cataract may initially affect a small area and progress to involve a larger portion of the lens. Rate of progression is difficult to predict, though it tends to be more rapid in younger animals. Cataracts may develop in one or both eyes.
• WHAT CAUSES CATARACTS? Most cataracts in dogs have a hereditary basis. Cataracts can also result from injury to or inflammation in the eye, or systemic diseases that have an affect on the eyes. Diabetes is the most common disease associated with cataracts in dogs. Although it may be difficult to name the specific cause of cataracts, generally those cataracts that develop in the eyes that are free of signs of disease (whether ocular or systemic) are assumed to be inherited. Poor nutrition is an uncommon cause of cataracts, but has been suspected in some young dogs.

Pertinent Anatomy

• The cornea is the clear window of the front of the eye.
• The Iris is the colored portion of the eye that controls the amount of light that is allowed into the eye.
• The Lens (as mentioned above) focuses the image on the retina
• The retina is the "electric" portion of the eye that converts the image into electrical signals that then are passed to the brain for assimilation of the image that is viewed.

What should you do if a cataract is suspected?

• First arrange to have your pet examined by a veterinary ophthalmologist. Although the lens is an important component of the visual system, a complete eye examination is necessary. Early examination is always recommended. 
• The health of the retina and other parts of the eye should be evaluated prior to the formation of complete cataracts. If the cataract is entirely mature, the area behind the lens may not be able to be examined directly. Therefore, in many cases an electroretinogram may be recommended to evaluate the retina. 
• The cataract will be classified by cause, area of involvement, and stage of progression. Not all cataracts lead to blindness, and incomplete cataracts may not impair vision significantly. Cataract surgery may be recommended if a pet has experienced vision loss.

Treatment

• Medical remedies have been inaccurately advertised as effective for the treatment of cataracts. There is no proven medical treatment known to reverse or slow the progression of, or prevent the formation of a cataract. Some promoted agents actually worsen the cataracts rather than improve the condition. 
• Surgery is the only known treatment both in animals and humans, and often provides a return of functional vision to pets.
• Indications for surgery:
  • Once the cataract has progressed to blindness in the affected eye, cataract surgery is often recommended. If one eye has a completely formed, vision-impairing cataract, and the opposing eye has a rapidly developing cataract, some veterinary ophthalmologists recommend surgery before the second cataract is complete. Surgery has been performed successfully on dogs and cats between 6 months and 18 years of age. The pet’s general health is evaluated before cataract surgery.
• Surgical procedure:
  • The various surgical procedures available for the dog are demanding and require meticulous and precise microsurgical techniques. Surgery is performed using an operating microscope and sophisticated microsurgical instruments. Two techniques are currently used to remove cataracts from the eye. One method involves making a large incision into the eye and removing the lens.
  • A newer method (termed phaco-emulsification) allows for a smaller incision, and may provide a better outcome for some animals. This procedure involves placing a small ultrasonic instrument into the eye (see illustration just above). This instrument generates about 40,000 tiny vibrations per second to fragment the cataract. The lens material is then aspirated out of the eye, much like a small intraocular vacuum. This sophisticated technique has been associated with a higher success rate for many cataract surgery patients.
  • Both techniques involve the removal of the damaged lens material. Artificial lenses can be positioned in the eye in place of the damaged lens before the completion of surgery. Pets usually benefit from cataract surgery with or without artificial lens implantation. The decision to place an intraocular lens in the eye should be discussed with your veterinary ophthalmologist.
  • Intraocular lenses are recommended in most dogs. An intraocular lens can be placed to improve the pets’ vision; however pets can still see without lens implants (see illustration to right - intraocular lens is in place). An artificial lens restores the vision to as close to normal as possible. Lens implants are available at Michigan Veterinary Specialists and are used with routine cataract surgery. In certain cases, instability of the lenses or inflammation may prevent the placement of an artificial lens. The specifics regarding your pets individual case will be discussed in detail with your doctor prior to surgery regarding lens implantation. Most pets can see and conduct routine activities following cataract surgery. 

Potential Complications

• The success rate in cataract surgery has improved markedly in the recent years with the advent of newer medications and microsurgical techniques. Although the success rate has risen dramatically, there are still several complications that need to be anticipated to prevent them. 
• Intraocular bleeding, elevation of intraocular pressures (glaucoma), post operative inflammatory response causing adhesions and scarring, retinal detachment, self-trauma, and infections are possible complications which may result in vision loss. 
• The risk of anesthesia is minimal. 
• The risk associated with surgery will be explained to you before the surgery is scheduled. 

Prognosis

• Our ophthalmology team has an excellent track record of successful cataract surgery
• It is essential that the retinal function be carefully evaluated prior to surgery to make sure that your pet will have vision after surgery.