Overview
This lecture covers the classification of cataracts with a focus on age-related (senile) cataracts and their stages of maturation, including key clinical features and risk factors.
Cataract Basics
- The lens is a transparent eye structure responsible for focusing light on the retina.
- Cataract is the loss of lens transparency, causing lens opacification or cloudiness.
- The word 'cataract' comes from a Greek word meaning waterfall, referring to its cloudy appearance.
Classification of Cataracts
- Etiological classification: congenital (developmental) or acquired (occurs after birth).
- Morphological classification: based on location/type (capsular, subcapsular, cortical, nuclear, polar cataracts).
- Congenital cataracts are usually partial and stationary, while acquired cataracts are progressive.
Senile (Age-Related) Cataracts
- Most common acquired cataract, typically seen after age 50, nearly universal above age 70.
- Risk factors: age, UV exposure, poor diet, dehydration, smoking, genetics, diabetes.
- UV light and oxidative damage alter lens proteins, causing opacification.
Types and Stages of Senile Cataracts
- Types: cortical (soft, affects cortex) and nuclear (hard, affects nucleus).
- Progression stages for cortical cataract:
- Lamellar Separation: lens fibers separate due to fluid, causing grayish pupil.
- Incipient Cataract: sectoral opacities with clear zones, two forms—cuneiform (peripheral wedge-shaped) and cupuliform (central, posterior subcapsular).
- Immature Cataract: most lens fibers opacified, some remain clear, iris shadow present.
- Intumescent Cataract: swollen lens due to increased fluid, risk of phacomorphic glaucoma.
- Mature Cataract: all fibers opacified, pearly white appearance, no iris shadow.
- Hypermature Cataract: further changes—Morgagnian (liquefied cortex, sunken nucleus) or sclerotic (shrinking, wrinkled capsule, possible lens subluxation).
Nuclear Senile Cataract
- Starts in the nucleus, hardens and spreads slowly; can have brown (brunescens), black, or rarely red appearance.
- Classified by color and density (e.g., using LOCS III classification).
Clinical Features and Signs
- Iris shadow indicates immature cataract; absent in mature cataract.
- Intumescent cataract may cause pupillary block and glaucoma (phacomorphic glaucoma).
- Hypermature cataracts show lens shrinkage, tremulous iris (iridodonesis), or lens movement (phacodonesis).
Key Terms & Definitions
- Cataract — Opacification or cloudiness of the lens.
- Senile cataract — Age-related lens opacity, common in elderly.
- Lamellar Separation — Separation of lens fibers by fluid.
- Incipient cataract — Early cataract with sectoral opacities.
- Intumescent cataract — Swollen lens due to fluid intake.
- Mature cataract — Complete lens opacification.
- Hypermature cataract — Advanced stage with liquefied or shrunken lens.
- Phacomorphic glaucoma — Glaucoma from swollen cataract lens.
- Iris shadow — Crescentic shadow on lens, seen in immature cataract.
Action Items / Next Steps
- Review the stages of senile cataract for exam preparation.
- Study the risk factors and morphological types in detail.
- Watch related videos on congenital cataracts and acquired cataract subtypes as referenced.