Types of Cataract

Cataracts are typed by where in the lens the clouding sits and why it developed - the type shapes symptoms and speed.

By location in the lens

• Nuclear cataract: clouding of the lens center - the commonest age-related type; slowly hardens and yellows, distance vision fades first, reading may briefly improve ("second sight")
• Cortical cataract: spoke-like white wedges from the lens edge inward - glare and contrast problems dominate; common in diabetics
• Posterior subcapsular cataract: a plaque at the back of the lens - the most visually aggressive; reading and bright-light vision suffer early, glare is severe; linked to steroids and diabetes; progresses in months, not years

By cause

• Age-related (senile): the great majority
• Diabetic (metabolic): earlier onset, faster progression - sugar control slows it
• Traumatic: after eye injury, even years later
• Steroid-induced: long-term steroid use
• Congenital/infantile: present at birth or developing in childhood - the vision-developing years make timing of treatment critical
• Secondary: after eye inflammation (uveitis), other eye surgery, or radiation
• Radiation and electrical injury cataracts: occupational and rare

Maturity grading (what the surgeon means)

• Immature: partial clouding, vision reduced but usable
• Mature: whole lens opaque - no useful vision
• Hypermature: the lens starts leaking or shrinking - now surgery becomes more urgent and more complicated; waiting this long costs the eye

The classical sorting

Classical texts typed lens-clouding disease by stage and pupil appearance (timira, kacha, linganasha with color descriptions), and separately listed the surgically approachable ones from the unapproachable - a type-and-operability sorting two millennia old.

One-line summary

Nuclear cataracts fade distance slowly, cortical ones scatter glare, posterior subcapsular ones steal reading fast - and hypermature cataracts are the penalty for waiting too long.