Katarakt

Cataracts are an opacification or thickening of the lens within the globe and are the leading cause of blindness in the world.

Clinical presentation

Visual deterioration occurs with increasing degrees of severity, and left untreated may present as complete blindness. The diagnosis is made clinically.

Pathology

Etiology

Common causes include:

• old age (most common)
• congenital (see: congenital cataract)
• post-traumatic
• diabetes mellitus (osmotic)
• radiation
  • e.g. 'radiation-induced cataract'  in the interventional radiologist

Radiographic features

Ultrasound

Ocular ultrasound is performed when there is suspicion of posterior globe pathology but funduscopic visualization of the back of the eye is obscured by the opaque lens.

• increased lens wall thickness and echogenicity

CT

Especially useful in acute cataract formation with increased fluid within the lens as in traumatic and osmotic cataract (hyperglycemia) as well as unsuspected lens injury. The affected lens is hypodense compared to the contralateral lens with a mean density difference of about 30 HU . 
CT is not the investigation of choice for the lens as the x-rays may worsen lens opacification.

Treatment and prognosis

Treatment is surgical extraction of the lens nucleus from its capsule and replacement with an intraocular lens implant into the native lens capsule (the presence of an implant instead of the native lens is called pseudophakia).

Siehe auch:

• künstliche Augenlinse in der Magnetresonanztomographie
• künstliche Augenlinse in der Computertomographie
• Operation des Grauen Stars
• MRI after cataract operation

und weiter:

• MRT OP Grauer Star
• Leukokorie
• Sonographie des Auges
• traumatic cataract