Describe the epidemiology.
Leading cause of visual impairment and blindness in the world
Prevalence of acquired cataracts: increases with age
> 80 years: ∼70 %
40–80 years: ∼17.5 %
Sex: ♀ > ♂
List causes for acquired cataracts (> 99%).
Age-related cataract (> 90%)
As a result of ocular diseases (complicated cataract)
Renal insufficiency (dialysis)
Previous retinal detachment
After intraocular surgeries
After vitrectomy (especially after silicone oil is inserted)
After filtration surgery in glaucoma
Glucocorticoids (local and systemic)
Miotics (cholinesterase inhibitors)
Chronic alcohol and tobacco use
Traumatic (traumatic cataract)
Bruise injuries (contusion cataract)
Physically related conditions
Radiation (x-ray, radioactive radiation)
Excessive sunlight or UVB exposure
High-voltage current, lightning
Infrared radiation (glassblower's and glass worker's cataract)
Posterior capsule opacification (PCO; or secondary cataract): clouding of capsule sections after extracapsular cataract extraction
List causes for congenital cataracts (<1%).
Hereditary congenital cataracts
Caused by TORCH infections (esp., rubella)
Associated with the following comorbidities/syndromes:
Trisomy 21 (in early childhood)
Neurofibromatosis type 2
How to classify cataracts?
Cataracts are generally classified according to etiology (as above). Age-related cataracts can also be classified according to where they form in the lens (morphology) or how advanced they are.
Cortical cataract (anterior/posterior): the most common type of cataract; characteristically originates at the outer layer of the lens and grows towards the center, forming a wedge-shaped opacity
Nuclear cataract: a type of cataract that affects the center of the lens, appearing as a yellow-brown discoloration of this area
Subcapsular cataract (anterior/posterior): a type of cataract that manifests directly under the lens capsule; usually in the posterior lens (rapidly progressive) but can also occur in the anterior lens
Stages of progression
Early stage of cataract progression
Red reflex is still present, allowing for visualization of the retina.
Advanced stage in cataract progression
Red reflex is absent.
There is a white-yellow discoloration of the lens due to complete clouding.
Vision can be reduced to mere light perception.
End stage of cataract progression
There is a complete white clouding of the lens due to liquification of the cortex.
The nucleus often sinks in the cortex and appears brown.