McCune Animal Hospital





Cataracts and Glaucoma – Seeing the Connection


Cataracts or opacity of the lens are one of the most common eye disorders in both humans and animals. While the exact incidence is unknown, cataracts represent one of the most common causes of blindness in dogs. Cataracts are often described as a haziness” or “cloudiness” in the eye that may or may not be associated with loss of vision. As the cataracts progress, the lens may take on a “crystalline” appearance and the pet may experience complete blindness.


There are six primary causes of cataract formation:


q   Hereditary – By far the most common reason; over 42 breeds of dogs are affected.

q   Inflammatory –Common cause in the cat; uveitis and infections of the eye can lead to cataract formation.

q   Metabolic – Diabetes mellitus can cause irreversible cataracts.

q   Traumatic – Blunt trauma and penetrating injuries of the eye can cause cataracts.

q   Nutritional – Puppies and kittens fed hand-replacement diets that are deficient in required amino acids.

q   Toxic – Electric shock, radiation therapy, and certain drugs.


Cataracts are classified based on their Stage of Development:


q   Incipient – Small opacities in the lens causing no clinical loss of vision. Often progress in near future.

q   Immature – More generalized opacity of the lens. Vision is often affected to some degree. Surgery is often indicated.

q   Mature – Dense opacity of the lens resulting in near total vision loss. Surgical removal of the cataract strongly encouraged.

q   Hypermature – “Wrinkled” lens capsule; blindness; danger of loss of the eye. Possibly too late for surgery.

q   Resorbing – Lens is degenerating and often leads to uveitis. Surgery is usually not recommended due to advanced state.


Treatment involves surgical removal of the cataract, often utilizing ‘laser surgery’ by a Board=certified veterinary ophthalmologist. Our staff veterinarians will make appropriate treatment recommendations and/or referrals for your pet.


Glaucoma is defined as an increase in the pressure of the eye or intraocular pressure (IOP). It is one of the most frequently misdiagnosed eye conditions. Glaucoma is a progressive and insidious disease that is often undiagnosed in companion animals until significant loss of vision occurs. Most pet owners will not notice a loss of vision until both eyes are affected.


Any inflammation of the eye and support tissues can cause an increase IOP. Any pet that has cataracts or red eyes should be checked for glaucoma. High IOP causes retinal damage by decreasing blood supply to the retina. Glaucoma that persists for as short as 24-hours usually results in irreversible blindness. Cataracts can cause glaucoma by physically blocking or slowing the fluid drainage channels thereby resulting in higher IOP>


Measuring IOP has never been easier. Our hospital is fortunate to have the latest Mentor Digital Applanation Tonometer that allows us to quickly and painlessly measure your pet’s IOP. This is the same instrument used by human ophthalmologist in hospitals worldwide. If your pet has cataracts, uveitis or other abnormalities of the eye, checking for glaucoma is often indicated to help prevent permanent blindness or vision loss. Pets with cataracts should be carefully monitored to detect subtle increased in IOP that may indicate surgery or medical therapy. Early detection and treatment is our only change to save a pet’s vision if glaucoma and/or cataracts develop