felis - Articles
Eye: lens luxation
Introduction
- Cause: lens luxation occurs when there is breakdown of the supporting lens zonules.
- In cats, lens luxation usually occurs secondary to other intraocular disease, in particular uveitis.
- Anterior lens luxation is associated with corneal damage and secondary glaucoma.
- Diagnosis: gross ocular and ophthalmoscopic examination should reveal above signs.
- Treatment: surgical lens extraction and treatment of other intraocular disease.
- Emergency treatment is rarely required (in contrast to dog).
- Prognosis: fair if treatment prompt and any other intraocular disease adequately controlled.
Presenting signs
- Lens in anterior chamber.
- Corneal opacity.
Age predisposition
- Most common in cats aged 7-9 years.
Breed/Species predisposition
- Siamese Siamese predisposed.
Pathogenesis
Etiology
- Primary luxation:
- Congenital:
- May be associated with microphakia.
- Hereditary
- Inheritance as a dominant trait possibly as a result of mutation in the FBN1 gene has been reported.
- Congenital:
- Secondary luxation:
- Uveitis Anterior uvea: traumatic uveitis.
- Glaucoma.
- Trauma.
- Cataract Cataract.
- Neoplasia.
Predisposing factors
General
- Pre-existing intraocular disease:
- Uveitis Uveitis: viral.
- Glaucoma Glaucoma.
Pathophysiology
- Lens luxation occurs when there is complete 360° breakdown of the lens zonules.
- Subluxation occurs when there is incomplete breakdown of the lens zonules.
- Breakdown of lens zonules may be a result of:
- Congenital or inherited weakness.
- Inflammatory damage.
- Globe stretching (glaucoma).
- External trauma.
- Cataract (increased lens weight).
- Damage from intraocular neoplasia.
- The lens may luxate anteriorly into the anterior chamber or posteriorly into the vitreous.
- Anterior lens luxation is most common and leads to further complications:
- Corneal edema:
- Owing to direct damage to corneal endothelium and compromise of pump mechanism responsible for keeping cornea relatively dehydrated and clear.
- Secondary glaucoma:
- Pupillary block from presence of lens and/or vitreous within pupil.
- Compromise of aqueous outflow via iridocorneal angle.
- Corneal edema:
- Retinal detachment Retina: detachment is another common long-term complication following lens luxation.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Maggs D J (2009) Feline uveitis. An 'intraocular lymphadenopathy'. J Feline Med Surg 11 (3), 167-182 PubMed.
- Townsend W M (2008) Canine and feline uveitis. Vet Clin North Am Small Anim Pract 38 (2), 323-346 PubMed.
- Payen G, Hänninen R L, Mazzucchelli S et al (2005) Primary lens instability in ten related cats: clinical and genetic considerations. JSAP 52 (8), 402-410 PubMed.
- Sansom J (2000) Diseases involving the anterior chamber of the dog and cat. In Practice 22 (2), 58-70 VetMedResource.
- Molleda J M, Martín E, Ginel P J et al (1995) Microphakia associated with lens luxation in the cat. JAAHA 31 (3), 209-212 PubMed.
- Olivero D K, Riis R C, Dutton A G et al (1991) Feline lens displacement - a retrospective analysis of 345 cases. Prog Vet Comp Ophthalmol 1 (4), 239-244 VetMedResource.