Dog - Lens Luxation

The lens is the transparent structure within the eye which assists focusing. It is a flattened sphere which is held in place by tiny ligaments around its circumference.

In some dogs, particularly terrier breeds, the ligaments can break down allowing the lens to dislocate from its normal position. It can fall backwards into the eye - posterior luxation - where it rarely causes discomfort. If it falls forwards - anterior luxation - it blocks the drainage of fluid from the eye allowing a build up of pressure. This is glaucoma which is a painful, blinding condition difficult to treat.

If the lens dislocates forward emergency treatment is required to reduce the risk of permanent damage to the eye. This usually entails specialist surgery so we will probably refer you to a veterinary ophthalmologist for this.

What signs will my dog show?

When the lens dislocates into the anterior (front) chamber it becomes very painful so the dog will close its eye. The eye will look red and cloudy and it is likely to have a watery discharge.

What does surgery involve?

This is performed by specialists and the dog will require general anaesthesia. Once the eye has been prepared for surgery it is opened with an incision near or through the clear cornea and the dislocated lens is removed. The eye is closed with sutures which are absorbable and do not need to be removed.

What is the postoperative care?

Your dog may have to be hospitalised for a few days after surgery for careful monitoring, treatment and rest. Once home it is vital that your pet is kept as quiet as possible and not allowed to jump, or to run up and down stairs. A protective collar may be necessary. Lead exercise only is allowed for a few weeks. Remember the eye has been opened and it does take time to heal. The veterinary ophthalmologist who performs the surgery will provide further post-op instructions.

Eye medication will be dispensed and it is important that instructions are carefully followed. If you have any problems at all it is important that you call us without delay.

Will my dog be able to see again?

The aim of the surgery is to alleviate discomfort and save vision as much as possible. If the lens has been dislocated for any length of time the chance of restoring vision is reduced although hopefully some sight will be restored. Cases treated sooner result in better vision but it will never be as good as prior to the lens dislocating since the eye can no longer focus on objects.

Are there any complications?

Complications can occur. These include persistent glaucoma (increased pressure within the eye) despite the fact the lens has been removed. This complication can be difficult to treat successfully although some patients respond well to certain drugs applied as eye drops.

Another potential complication is retinal detachment. The retina (light sensitive surface) is dislodged as the lens has moved forwards. These eyes often remain sightless but they are usually pain free.

What causes lens luxation?

Weakness of the lens ligaments is known to be hereditary in several terrier breeds (e.g. Jack Russell Terrier, miniature English Bull Terrier, Tibetan Terrier) and also the Border Collie. Therefore, in these breeds if one lens has luxated, it is almost certain that the same thing will happen to the other eye at a later date. It is important that you watch for any signs of discomfort or change in appearance of the eye. Call us immediately if you are at all concerned. Occasionally the lens can luxate as a result of other damage in the eye - long standing glaucoma or severe trauma to the eye are examples. In these cases surgical removal of the entire eye may be necessary since removing the lens only would not cure the underlying problem.

How quickly does the lens luxate?

Before the lens falls out of position completely it can 'wobble' as some of the ligaments break, with a few still remaining to keep it loosely in place. This is what is known as sub-luxation of the lens. The eye still looks normal to the owner, and causes the dog no pain. A specialist veterinary ophthalmologist is able to detect such lens instability. Some veterinary ophthalmologists choose to operate on these subluxated lenses before they dislocate completely since this avoids the pain and glaucoma that can follow total anterior luxation. However others prefer to leave them until the lens has fully luxated since the potential complications are still present if the lens is operated on when subluxated. In some dogs, treatment with eye drops can reduce the risk of glaucoma while the lens is subluxated but there is no known treatment to prevent the unstable lens from fully dislocating eventually

What happens if the lens falls backwards instead of forwards (posterior luxation)?

When the lens falls into the back of the eye it causes little or no discomfort. These cases can sometimes be monitored or treated with drops rather than requiring emergency surgery. The surgery is technically very demanding and the risk of complications greater. The lens is not fixed in the back of the eye so it can still move around in the eye and can sometimes fall forwards, converting into an anterior luxation. This can be followed by discomfort and blindness as already described and surgical removal is then urgently required.

What is the prognosis?

The prognosis for all cases of lens luxation is guarded. This very serious ocular (eye) disease can result in pain and blindness. Sometimes the eye needs to be removed if it has become badly damaged with the dog blind and in pain. If inherited the other eye is always at risk, and regular specialist monitoring is essential to provide the best long term outlook for the dog.

If you have any queries, please do not hesitate to contact us.