Overview
This lecture explains the classification of cataracts, with a particular focus on age-related (senile) cataracts, their risk factors, morphologic types, and maturation stages.
Definition and Origin of Cataract
- Cataract is the loss of lens transparency due to opacification, causing cloudiness.
- The term "cataract" comes from the Greek word for waterfall, reflecting its cloudy appearance.
Classification of Cataracts
- Etiological classification:
- Congenital (developmental) cataracts arise during lens formation, often stationary and partial.
- Acquired cataracts develop after lens formation due to various triggers and usually progress, covering the entire lens.
- Morphological classification:
- Capsular (at capsule), subcapsular (just beneath capsule), anterior/posterior subcapsular, cortical (cortex), nuclear (nucleus), and polar (at poles, anterior or posterior).
Senile (Age-Related) Cataracts
- Most common acquired cataract, typically occurs after age 50.
- Universal in those over 70; earlier onset linked to UV exposure, poor diet, dehydration, and smoking.
- Risk factors include age, diabetes (earlier onset, commonly nuclear type), hereditary factors, UV exposure, and certain metabolic disorders.
Stages of Maturation of Senile (Cortical) Cataract
- Stage of Lamellar Separation: Fluid accumulates between lens fibers, causing separation and grayish pupil appearance; reversible.
- Stage of Incipient Cataract:
- Opacities form with clear spaces; two types:
- Cuneiform (wedge-shaped, peripheral, slow central progress)
- Cupuliform (saucer-shaped, central, rapid visual loss, mainly near vision)
- Stage of Immature Cataract:
- Partial lens opacification; iris shadow present due to clear lens areas.
- Intumescent cataract may occur (lens swells), risk for phacomorphic glaucoma.
- Stage of Mature Cataract:
- Entire cortex opacified, pearly white "ripe" appearance; no iris shadow.
- Stage of Hypermature Cataract:
- Morgagnian: Cortex liquefies, mobile nucleus sinks.
- Sclerotic: Cortex shrinks, capsule wrinkles, possible lens/iris tremulousness.
Stages of Nuclear Senile Cataract
- Begins in nucleus, spreads outward slowly; color changes from gray to yellow to brown (brunescence).
- Hard, dense cataracts; rare reddish or black varieties exist.
Key Terms & Definitions
- Cataract — loss of lens clarity due to opacification.
- Senile cataract — age-related lens opacity, progressing with age.
- Lamellar Separation — initial separation of lens fibers by fluid.
- Intumescent cataract — swollen lens due to fluid absorption.
- Phacomorphic glaucoma — glaucoma secondary to swollen cataractous lens.
- Iris shadow — crescentic shadow seen in immature cataracts with clear lens areas.
- Morgagnian cataract — hypermature cataract with liquefied cortex and sinking nucleus.
- Brunescence — brown discoloration of nuclear cataract.
Action Items / Next Steps
- Review the anatomy of the lens, focusing on fiber arrangement and transparency.
- Study diagrams or clinical images of cataract types and stages for visual understanding.
- Prepare for questions on distinguishing features of different cataract stages and types.