Sealyham Terrier Health Information Central



Lens Luxation: a brief overview

By George Packard, director, Institute for Genetic Disease Control (GDC)

[Every effort has been made to ensure accuracy of information.  However, this is not a substitute for prompt veterinary care.  Any similarity to other publications is unintentional. Published online at, 12/7/10]

Download PDF version

What is Lens Luxation?

Lens Luxation is a genetic disease caused primarily by a defective gene that controls the strength of the fibers (zonules) that hold the lens in place.

At this point, we need to assume that almost every Sealyham is at some risk for lens luxation. The best way to know for sure is to have your tested with the Lens Luxation DNA test [ LensLuxationDNATest.aspx] to find out whether he is at risk for being affected by the disease. If he is at risk, have your dog's eyes examined every year by your vet as part of his routine exam, or by a veterinary ophthalmologist (CERF exam).

If the DNA test shows that your dog is not carrying the mutated gene which causes Lens Luxation, then you would not need to continue to have his eyes examined for Lens Luxation.

The condition can happen suddenly, and owners need to be alert to symptoms as well. (See below for symptoms).

The lens is held in position behind the iris by very fine fibers. If a dog inherits from both parents a copy of the mutated gene that causes lens luxation , there is a very high probability that those fibers, in both eyes, will weaken and break. A dog with the genes for lens luxation may not become affected until the age of 4-8.

The lens at first will move from its normal position (called subluxation). If the fibers break, the lens will slip, or luxate, from position, and may move either forward or backward inside the eye.

When the lens slips from position it often blocks the flow of fluid in the eye, and the resulting rise in pressure may cause glaucoma which will result in irreparable damage to the retina and optic nerve within 72 hours.

If the eye is not damaged by glaucoma, most dogs will still have some vision even with the lens surgically removed. In many cases, the lens in the second eye may be still partially attached, and drug therapy to treat the glaucoma may help to slow the luxation of that lens.

Symptoms of Lens Luxation

Call your vet immediately if your dog shows any of the following:

  • Excessive pus-like matter in the corner of the eye
  • Indications of pain or discomfort in the eye
  • Changes in the inside appearance of the eye

Revised 12/7/10



Copyright 2008-2024, American Sealyham Terrier Club