PLL – Primary Lens Luxation

What is Primary Lens Luxation?

The lens of the eye normally lies immediately behind the iris and the pupil, and is suspended in place by a series of fibers, called zonular ligaments. It functions to focus light rays on the retina, in the back of the eye. When partial or complete breakdown of the zonular ligaments occurs, the lens may become partially dislocated (Lens Subluxation) or fully dislocated (Lens Luxation) from the lens’ normal position. PLL occurs when the lens spontaneously detaches from its normal residence within the pupil, leading to reduced visual acuity. Anterior lens luxation is when the lens falls forward and posterior lens luxation is when the lens falls backwards in the eye.

Primary Lens Luxation is a heritable disease in many breeds, including many terrier breeds (Jack Russell, Bedlington, Fox, Manchester, Miniature Bull, Scottish, Sealyham, Welsh, West Highland White), Tibetan Terrier, Border Collie, Brittany Spaniel, German Shepherd and Welsh Corgi. In these breeds, spontaneous luxation of the lens occurs in early adulthood (most commonly 3-6 years of age) and often affects both eyes, although not necessarily at the same time. Primary Lens Luxation is caused by an inherent weakness in the zonular ligaments which suspends the lens.

Lens Luxation can also occur secondary to other primary problems of the eye, including inflammation, cataracts, glaucoma, cancer, and trauma.

What is the Significance of Lens Luxation?

Lens Luxation can lead to inflammation (Uveitis) and Glaucoma (increased intraocular pressure). This can result in painful, teary, red eyes that may look hazy or cloudy. Both Uveitis and Glaucoma are painful and potentially blinding diseases if not identified and treated early.

How is Lens Luxation treated?

In all cases, a thorough eye exam by your veterinarian or a veterinary ophthalmologist is required, with careful evaluation for uveitis and glaucoma. If detected early, surgical removal of the lens can be beneficial. Medical treatment of inflammation and glaucoma in the form of topical and oral medications can relieve much of the discomfort associated with this disease.

Test Results

  • Normal: This dog has tested normal/clear for the mutation known to cause Primary Lens Luxation (PLL) in this breed. It can only transmit the normal/clear gene to its offspring.

  • Carrier/Low Risk: This dog has tested as a carrier/low risk for the mutation known to cause Primary Lens Luxation (PLL) in this breed. This means the dog has one normal/clear copy and one mutated copy of the gene, and has a slight (5-10%) risk of developing Primary Lens Luxation. Either the normal/clear copy or the mutated copy of the gene can be transmitted to its offspring.

  • Affected/High Risk: This dog has tested as affected/high-risk for the mutation known to cause Primary Lens Luxation (PLL) in this breed. It is at risk for developing clinical symptoms of PLL at some point in its lifetime, usually between 4-8 years of age. It can only transmit the mutated copy of the gene to its offspring.

About PLL

When signs & symptoms develop in affected dogs
Signs of this disease typically first appear in adulthood (3-8 years on average).

How vets diagnose this condition
Your veterinarian will examine your dog’s eyes carefully and determine if it is an anterior or posterior luxation. They may run additional tests to check for secondary complications.

How this condition is treated
Surgical correction by a veterinary ophthalmologist is necessary if the lens falls forward (anterior lens luxation). No treatment may be required except careful monitoring if the lens falls backward (posterior lens luxation).

Actions to take if your dog is affected
The best care you can provide your dog is seeking the expert opinion of your veterinarian for an accurate diagnosis and determining whether or not a specialty consult for surgery is required.

More information
This mutation was first identified in the Jack Russell Terrier, Lancashire Heeler, and the Miniature Bull Terrier.

Gene name

Inheritance type

Farias et al 2010 , Gould et al 2011

Information from OFA and Embark Testing Websites supplied by the University of Missouri-Columbia College of Veterinary Medicine.

A genetic test is not a diagnosis.

This genetic test does not diagnose a disease.

Please talk to your vet about your dog’s genetic results, or if you think that your pet may have a health condition or disease.