Lens Luxation in Dogs

In normal circumstances, the lens is usually hovering between the colored part of the eye and the clear part of the back of the eye. The suspensory ligaments and zonules hold it all in place. If the zonules are broken, then the lens becomes partially dislocated and will fall into the front of the pupil’s anterior chamber, shifting from its usual position or being completely put out of place. When the lens is detached, it can go through two different processes. Anterior luxation is when it falls into the front of the pupil’s anterior chamber. Posterior luxation is when it falls into the back of the eye. If you notice any sign that your dog’s eyes have suddenly changed or he seems to be squinting a lot, a veterinarian visit is warranted.

The movement of the lens of the eye whether into the posterior or anterior chamber is described as lens luxation.

Partial dislocation or subluxation can be easily detected during an eye exam at the veterinarian. However, most symptoms are seen when the lens falls into the front of the pupil’s anterior chamber. The signs are not so apparent with posterior luxation. Some of the general signs are:

• Sudden change in the way your pet’s eyes look; in fact, eyes may look as if they are turning white
• Pain while squinting or keeping the eyes closed
• Increased tears
• Inflammation of the eyes, showing cloudiness and possibly redness
• Reluctance to exercise
• Depression

There are both primary and secondary causes that are indicative of the origin of lens luxation. The primary cause of lens luxation is heredity, causing the degeneration of the suspensory or zonular fibers. This occurs mostly in Terrier dogs such as:

• Tibetan Terrier
• Wire Haired Fox Terrier
• Smooth Haired Fox Terrier
• Scottish Terrier
• Welsh Terrier

In addition to Terriers, the condition can also be found in the Australian Cattle Dog, Border Collie, Shar-Pei and occasionally in other dog breeds.  Both eyes are often affected.

If the condition is secondary lens luxation, this occurs after your dog has experienced an eye disorder. Usually, only a single eye is affected. The condition might be related to:

• Inflammation
• Eye trauma
• Glaucoma
• Idiopathic

The veterinarian will first examine the anterior chamber of the lens for an appropriate diagnosis. The veterinarian may also look at the cavity floor of the vitreous. Other diagnostic examination would include, but not limited to:

• Complete eye evaluation
• Tonometry for detecting glaucoma
• Fluorescein staining – this eliminates corneal ulcer
• Use of a slit lamp during examination to check the positioning of the lens locally and the deepness of the anterior chamber
• Evaluating the front of the eyes for inflammation
• Retinal exam
• Blood count
• Serum biochemistry
• Immunologic exam
• ERG or Electroretinogram to check the dog’s vision

Additionally, an ultrasound may reveal clues to the extent of the luxation, particularly in the case of a partial dislocation.

Lens luxation is treated according to how the lens in the eyes is located. The veterinarian has to also see if glaucoma is present. The objective is to lower the pressure inside the eyes. The veterinary specialist will also want to surgically remove the luxated lens in the anterior chamber, if there is likelihood that the vision can be saved. The veterinarian will also treat underlying causes. 

An acute luxation is an emergency and treatment should be administered immediately. The first thing that the veterinarian will do is evaluate the eye for vision possibility. Your dog could go blind if the increased pressure and luxation has gone for more than 48 hours without treatment. The increased pressure also causes pain. The optic disc and retina will appear healthy if there is no severe glaucoma or if the luxation is acute. The veterinarian could save your dog’s vision in such case with surgery. 

Other treatment options could include:

• Controlling glaucoma and anterior uveitis
• Removing the eye if there is pain
• Surgically removing the lens in the front chamber, though complications may remain such as inflammation

After the initial treatment, the dog’s eye pressure has to be closely monitored. Medications should be administered according to the veterinarian’s instructions. Schedule a follow up visit to the veterinarian as advised. There is a chance of secondary complications; if your dog seems to be uncomfortable or in pain contact the clinic for an appointment.