Introduction

• A cataract is an opacification of the lens.
• May be primary (breed-related) or secondary due to disease (uveitis, diabetes, PRA).
• Developmentally staged as incipient, immature (tapetal reflex present), mature (no tapetal reflex/blindness) and hypermature (wrinkled lens capsule).
• Either congenital, eg Miniature Schnauzer, Boston Terrier, Welsh Springer Spaniel, at early age, eg Afghan Hound, German Shepherd dog or at later stage, eg Standard Poodle.
• Usually inherited (autosomal recessive).
• Inherited as incomplete dominant in Labrador Retriever, Golden Retriever (posterior subcapsular opacity).
• Good prognosis if phacoemulsification performed and if no other ocular structures involved.
• Early developing cataract: remove at an early stage either by irrigation, aspiration, extracapsular extraction or phacoemulsification → prevents lens-induced uveitis.

Pathogenesis

Etiology

• Genetic defects.
• Secondary to uveitis, involving changes such as:
  • Posterior synechiae.
  • Altered aqueous humor in uveitis.
• Radiation.
• Diabetes mellitus Diabetes mellitus.
• Hypocalcemia Primary maternal dystocia.
• Senile cataracts.
• Degenerating retina (PRA).
• Nutritional (milk replacers).

Predisposing factors

• Breeds at risk.
• Old age.

Pathophysiology

• Lens opacification is termed a cataract.

• Cross-linking of lens proteins causes lens opacification.

Timecourse

• Incipient cataracts can progress to immature, mature and hypermature stages, although these stages are not mutually exclusive.
• Nuclear cataracts may become relatively smaller with time as the lens cortex grows in size.
• Cortical cataracts almost always progress.

Diagnosis

Treatment

Prevention

Outcomes