Overview
This lecture covers the classification and stages of cataract, focusing on age-related (senile) cataract, its risk factors, types, and detailed progression.
Cataract Basics
- Cataract is the loss of lens transparency due to opacification, causing cloudiness and impaired vision.
- The lens is transparent because of regularly arranged fibers and absence of organelles, minimizing light scatter.
Classification of Cataracts
- Etiological classification: divided into congenital (present at birth or during development) and acquired.
- Morphological classification: based on location and appearance of opacity (capsular, subcapsular, cortical, nuclear, polar).
- Congenital cataracts are typically partial, stationary, and develop during lens formation; acquired cataracts develop after lens formation and are progressive.
Senile (Age-Related) Cataract
- Most common acquired cataract, usually occurs after age 50.
- Risk factors: age, UV exposure, poor diet (low in protein, riboflavin, vitamins E and C), dehydration, smoking, family history, diabetes, and certain diseases.
- Pre-senile cataract: senile cataract appearing before age 45-50, but not developmental.
Molecular Mechanism & Risk Factors
- UV radiation, poor nutrition, and smoking cause biochemical changes, disorganizing lens proteins and leading to clouding.
- Smoking introduces compounds that cause protein denaturation; hereditary and metabolic diseases accelerate onset.
Types of Senile Cataract
- Classified into cortical cataract (soft, cortex affected) and nuclear cataract (hard, nucleus affected).
- Cortical cataracts progress through recognizable maturation stages.
Stages of Cortical Senile Cataract
- Lamellar Separation: Fluid collects between lens fibers, causing separation; reversible, pupil appears grayish.
- Incipient Cataract: Early opacities with clear spaces; includes cuneiform (wedge-shaped, peripheral) and cupuliform (saucer-shaped, central, affects near vision early).
- Immature Cataract: Most lens fibers are opacified, but some remain clear; partial loss of clarity, iris shadow seen.
- Intumescent Cataract: Swollen lens absorbs more fluid, can cause pupillary block and phacomorphic glaucoma.
- Mature Cataract: Complete opacification, no iris shadow, appears pearly white (ripe cataract).
- Hypermature Cataract: Includes Morgagnian type (liquefied cortex with sunken nucleus) and sclerotic type (shrunken, wrinkled, thickened capsule, possible subluxation).
Maturation of Nuclear Senile Cataract
- Opacification starts in the nucleus and spreads slowly; can have different colors (brown, black, red).
- Hard nuclear cataracts are called "cataracta brunescens" (brown).
Key Terms & Definitions
- Cataract — Opacification or clouding of the lens.
- Senile Cataract — Age-related opacity, typically after age 50.
- Lamellar Separation — Early stage with fluid between lens fibers.
- Cuneiform Cataract — Wedge-shaped peripheral opacities.
- Cupuliform Cataract — Central, saucer-shaped opacity.
- Intumescent Cataract — Swollen lens from excess fluid uptake.
- Phacomorphic Glaucoma — Secondary glaucoma due to swollen cataractous lens.
- Morgagnian Cataract — Hypermature cataract with liquefied cortex and mobile nucleus.
- Iris Shadow — Crescent shadow seen in immature cataract.
- Iridodonesis — Trembling of the iris due to shrunken lens.
- Phacodonesis — Trembling of the lens.
Action Items / Next Steps
- Review the stages and clinical features of senile cataract for exams.
- Prepare to study developmental and other acquired cataracts in upcoming sessions.