Cataract

• Rare.
• Cause: inherited (juvenile or later onset), or secondary to systemic disease or ocular abnormality (eg uveitis).
• Signs: cloudy eye, blindness.
• Diagnosis: signs, ophthalmology.
• Treatment: surgical removal of lens.
• Prognosis: good following surgical removal of lens (with or without intraocular lens implantation).
  Print off the owner factsheet Cataract Cataract to give to your client.

• Persian Persian longhair, Himalayan, Birman Birman, and British shorthair British shorthair where cataract may be inherited.

• If removal of the lens is indicated.

Inherited

• Uncommon - if occurs is usually congenital.
• Posterior polar suture line opacity (Y suture area).
• Nuclear cataract.

Metabolic

• Very rare (much more so than dog).
• Diabetes mellitus Diabetes mellitus (but cataract not seen at the same incidence as in diabetic dogs).
• Hyperparathyroidism Primary hyperparathyroidism.
• Secondary nutritional cataract  .

Secondary

• Uveitis Anterior uvea: traumatic uveitis.
• Lens luxation   Eye: lens luxation  .
• Penetrating wound, eg cat scratch (often focal associated with focal posterior synechia).
• Generalized progressive retinal atrophy   Retina: degeneration  (very rare).

General

• May be associated with Chediak-Higashi syndrome Chediak-Higashi syndrome.

• Diabetes mellitus   →   increased lens glucose   →   accumulation of insoluble sugars with osmotic potential   →  water influx  →   cataract but not seen in cat as frequently as dog.
• Uveitis   →  inflammation  →   cataract.
• Trauma   →   free radical formation (possibly)   →   cataract.
• Generalized progressive retinal atrophy   →   complex mechanisms (lipid peroxidation biproducts giving cataract (but not in cat as in dog))   →   cataract.

Subsequent progress

• Cataract development varies: cortical cataracts may progress, capsular lesions are usually stable.

• Very variable: diabetic cataracts often progress rapidly; post-trauma cataracts develop at very varying rates.

• Cloudy eye.

• Grayness in the eye.

Ophthalmoscopy

• Retina obscured on direct ophthalmoscopy Ophthalmoscopy: direct.
  Set ophthalmoscope on zero.

• Nuclear sclerosis - older animals, does not compromise vision, retina visible but concentric rings in cortex due to refractive index changes.

• Phacoemulsification Phacoemulsification: - early operation when eye still has vision avoids secondary problems, eg lens -induced uveitis   →   higher success rate.
• Should only be performed by veterinary ophthalmologist.
  Surgery not appropriate for inflammatory disease. May be successful for traumatic disease if performed early, eg within days of injury.

• Good following surgery if underlying disease controlled.

• Standard reasons Standard reasons for failure in a treatment.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Remillard R L, Pickett J P, Thatcher C D et al (1993) Comparison of kittens fed queen's milk with those fed milk replacers. Am J Vet Res 54 (6), 901-907 PubMed.
• Curtis R (1990) Lens luxation in the dog and cat. Vet Clin North Am Small Anim Pract 20 (3), 755-773 PubMed.
• Quam D D, Morris J G, Rogers Q R et al (1987) Histidine requirement of kittens for growth, haematopoiesis and prevention of cataracts. Br J Nutr 58 (3), 521-532 PubMed.
• Whitley R D, Moore C P (1984) Advances in feline ophthalmology. Vet Clin North Am Small Anim Pract 14 (6), 1271-1288 PubMed.

Other sources of information

• Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology .2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4