If glaucoma is allowed to remain untreated for as little as six hours, then your dog will be fully blind in that eye.It important that the dog is immediately seen by a vet who is fully knowledgeable in this subject. Most vets aren’t, or don’t appreciate the seriousness of the situation. This is an ACUTE condition requires urgent attention...

If your Shar-Pei is showing signs of eye irritation it is important that your Vet examines the eye thoroughly, closing, rubbing, discomfort, apparent bad vision, watery eyes, can all be attributed to a number of complaints some minor, some can be much more serious, Even behaviour where your Shar-Pei seems to have difficulty sometimes, at recognizing friends, or being easily startled, can be a pointer to eye problems including Lens Luxation.
Lens Luxation can be seen by any vet but needs a thorough eye examination instead of the quick diagnosis which so often only brings a tube of eye cream into use.

Primary Lens Luxation in the dog may be classified as Primary or Secondary. Primary Luxations, in which prior ocular disease cannot be identified, are commonly considered to be hereditary, and are thought to be due to weakened or aberrant lens zonules that rupture early in life.

A pedigree analysis of a family of 15 related Chinese Shar-Pei was carried out in the USA by members of the American College of Veterinary Opthalmology.  This pedigree analysis, included affected and non-affected dams, sires and offspring, and was compiled to document and characterize the occurrence, common clinical signs, and age of onset of Primary Lens Luxation while suggesting a possible mode of inheritance in the Shar-Pei.
Of the five offspring from the mating of an affected dam to two unrelated affected males, 100% of offspring were affected with bilateral primary Lens Luxations. Of the four viable offspring from the mating of the same affected dam to an unrelated, unaffected male, two dogs (50%) were affected.
The average age of onset of affected animals (seven) in this first generation was 4.9 years (range 3—6 years).
The six dogs in the second generation of the same pedigree line were 2-years-old at examination with none of these animals affected at the time of the study.
The most common presenting complaints were a unilateral change in ocular appearance (5 of 7 dogs) and subjective vision impairment (4 of 7 dogs). The most common clinical sign upon ophthalmic examination was iridodonesis (unilateral 4 of 7 dogs; bilateral 3 of 7 dogs) and the presence of an aphakic crescent (3 of 7 dogs). Gonioscopy and tonometry of severely affected eyes revealed a narrow or closed iridocorneal angle and ocular hypertension.

The study suggests that primary Lens Luxation occurs in the Chinese Shar-Pei, resembling the clinical condition (age of onset, clinical signs) found in the terrier breeds, the Border Collie, and the Tibetan Terrier.

Application of the phenotypic findings in this study to a Mendelian genetic model of inheritance suggests that primary Lens Luxation in the Chinese Shar Pei is inherited as a simple autosomal recessive trait.

There was also another study carried out by the Virginia- Maryland Veterinary Teaching Hospital (1990-1996), Out of the records of 55 Shar-Pei …11 were diagnosed as affected with Primary Lens Luxations.
 This study suggests that Primary Lens Luxation does appear in the Shar-Pei and seems to be Identical and consistent with the autosomal recessive condition characterized in the Tibetan Terrier, from  reports of Lens Luxations and sudden blindness in young adult Shar-Pei, it would seem that in the study area in the US, the condition is not uncommon, with 20% of Shar-Pei examined, showing that they were affected with Lens Luxations.

What is a Lens Luxation? With this disorder there is abnormal positioning of the lens within the eye. Normally the lens is suspended between the iris and the retina, held in position by the lens zonules (a bit like an upturned trampoline) and the adjacent vitreous (Soft jelly like substance inside the eye…see diagram). There can be partial (sub-luxation) or complete displacement (luxation) of the lens from its normal site, either forward into the anterior chamber of the eye (in front of the pupil) or backward into the vitreous.

		a) normal lens position b) anterior luxation forcing the iris forward. This results in a very shallow anterior chamber c) lens is partially through the pupil. If the lens touches the cornea, edema of the cornea will result d) complete anterior luxation. The anterior chamber is very deep as it contains the whole lens. Pupillary block is present.

Forward (anterior) Lens Luxation in particular, may cause an increase in the pressure within the eye (glaucoma), which if untreated leads to blindness.
Lens Luxation may be primary (inherited), in The Shar-Pei along with other breeds predisposed as listed below. Secondary luxation may occur in any breed as a result of trauma, inflammation, glaucoma or an intraocular tumour.  

How is Lens Luxation inherited?
The mode of inheritance is not defined.

What other breeds are affected by Lens Luxation?
 

What does Lens Luxation mean to your dog & you?
Inherited (primary) Lens Luxation occurs in young to middle-aged animals of 3 to 7 years. The lens usually displaces forward into the anterior chamber.  In older animals, the lens displaces more easily backwards into the vitreous space.

A lens that displaces forward into the anterior chamber will often cause increased pressure within the eye leading to glaucoma. This is an emergency, as increased intraocular pressure can cause blindness within several hours. Your dog will experience intense pain and tearing of the eye, as well as reduced vision. With these signs, your dog should see your vet immediately to prevent irreversible loss of vision.

Other signs of Lens Luxation are that your dog's eyes may appear asymmetrical to you or the affected eye may look cloudy. Sub-Luxations and Posterior Luxations may ultimately result in glaucoma as well.

In predisposed breeds, Lens Luxation often occurs in both eyes at the same time, or in the second eye within a few months of the first.

How is a Lens Luxation diagnosed?
With an Anterior Luxation, your Shar-Pei may show intense pain (rubbing, pawing at the eye), tearing and visual impairment associated with glaucoma. Alternately, your dog may show no clinical signs associated with the Lens Luxation (usually a Sub- or Posterior Luxation) and your vet may observe an ocular abnormality during a routine physical examination. He/she will examine your dog's eye with an ophthalmoscope and measure the intraocular pressure. This can usually be done with local anaesthetic drops placed in your dog's eye and causes no discomfort to them.

 For The Vet:

1. Physical Exam: may see blepharospasm, epiphora, central corneal edema
2. Opthalmoscopic Exam: may see increased or decreased anterior chamber depth, iridodonesis, aphakic crescent, central corneal edema; with anterior displacement the IOP is generally elevated. IOP (Intraocular pressure) of 50 mm Hg or more will lead to permanent optic nerve and retinal damage within hours if not relieved); IOP may be decreased due to uveitis caused by lens irritation.

How is a Lens Luxation treated?
Treatment depends on the location of the lens (anterior or posterior), the presence or absence of acute glaucoma, and the potential for vision. 

With sudden anterior Lens Luxation, your vet will immediately start medical therapy for glaucoma. The lens should be surgically removed as soon as possible.  If the intraocular pressure is elevated, then surgery is urgent to prevent permanent damage to the retina and optic nerve. Pressures over 50 mm Hg will cause such damage within hours.

For dogs with anterior Lens Luxation that have become blind, glaucoma can be treated by removing the globe of the eye (enucleation). This will eliminate the pain for your dog. It is also possible to inject the eye with a long lasting drug which will effectively reduce the pressure and any discomfort. There are also procedures that can be done that preserve the globe such as placing a prosthesis.

Posterior Luxated Lenses are difficult to remove surgically. As long as the lens can be maintained in that position, problems with vision are less likely. Long-term eyedrops can be used to keep the pupil small and the lens behind it.

It is possible to replace the removed lens with an artificial substitute, but this is not generally very successful, mainly due to the *design of the artificial lens (*The fixings on the lens are not good), however lens replacement in humans has a higher success rate due to a better design, an optical lens manufacturer in France has indicated that they would be prepared to manufacture a lens to the human design for use in dogs on request. 

Breeding advice
Primary Lens Luxation is assumed to be autosomal recessive. That is, each parent must at least be a carrier of the disorder. If a dog is affected, certain facts are known...... both parents are at least carriers and every offspring of the affected dog is a carrier. Affected dogs should not be bred and known carriers should be pulled from the breeding program.
However this condition often does not occur before 3 to 7 years of age, making it difficult to identify affected dogs before they are used for breeding.
(Secondary Lens Luxation is associated to trauma to the eye, such as puncture or injury, and is not hereditary)

Remember that quick diagnosis and rapid skilled treatment of Lens Luxation could save your Shar-Pei’s eyesight

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