Description
- A condition in which the normally clear lens of the eyes become opaque, which results in decreased or blurry vision
- The word ‘cataract' has been derived from the Greek word 'katarraktes’ which means waterfall’
- Patients( usually between 50- 70 years) frequently complain of Web-like appearance, blurry vision, sensitivity to light and glare, Increasing difficulty with vision at night, Double vision, and haloes from lights should be suspected as cataract cases
CLASSIFICATION
Etiological classification
- Congenital and developmental cataract
- Acquired cataract
- Senile cataract
- Traumatic cataract
- Complicated cataract
- Metabolic cataract
- Electric cataract
- Radiational cataract
- Toxic cataract
- Cataract associated with skin diseases (Dermatogenic cataract)
- Cataract associated with osseous diseases
- Cataract with miscellaneous syndromes
Morphological classification
- Capsular cataract. It involves the capsule and maybe
- Anterior capsular cataract
- Posterior capsular cataract
- Subcapsular cataract. It involves the superficial part of the cortex (just below the capsule)and includes
- Anterior subcapsular cataract
- Posterior subcapsular cataract
- Cortical cataract. - involves the major part of the cortex
- Supranuclear cataract. - involves only the deeper parts of the cortex (just outside the nucleus)
- Nuclear cataract. - involves the nucleus of the crystalline lens
- Polar cataract. - involves the capsule and superficial part of the cortex in the polar region only and may be:
- Anterior polar cataract
- Posterior polar cataract
Congenital and developmental cataracts
- Congenital and developmental cataracts occur due to some disturbance in the normal growth of the lens. When the disturbance occurs before birth, the child is born with a congenital cataract. Therefore, in congenital cataract, the opacity is limited to either embryonic or foetal nucleus
- A developmental cataract may occur from infancy to adolescence. Therefore, such opacities may involve infantile or adult nucleus, deeper parts of cortex or capsule.
Acquired cataract
- In acquired cataract, opacification occurs due to degeneration of the already formed normal fibres
Age-related cataract
- Is the commonest type affecting either sex usually above the age of 50 years
- Usually bilateral, but almost always one eye is affected earlier than the other
Morphologically, the senile cataract occurs in two Forms
- Cortical (soft cataract)
- Nuclear (hard cataract)
The cortical senile cataract may start as
- Cuneiform (more commonly)
- Cupuliform—Posterior Sub Capsular (PSC) cataract
Stages of Maturation
Maturation of the cortical type of senile cataract
- Stage of lamellar separation- The earliest senile change is the demarcation of cortical fibres owing to their separation by fluid. This can be demonstrated by slit-lamp examination only. These changes are reversible
- Stage of incipient cataract - In this stage, early detectable opacities with clear areas between them are seen. Two distinct types
- Cuneiform senile cortical cataract - wedge-shaped opacities with clear areas in between
- Cupuliform senile cortical cataract - saucer-shaped opacity develops just below the capsule
- Immature senile cataract (ISC) - Opacification progresses further. The lens appears greyish white but clear cortex is still present and so iris shadow is visible. In some patients, at this stage, the lens may become swollen due to continued hydration. This condition is called ‘intumescent cataract’
- Mature senile cataract (MSC) - Opacification becomes complete, i.e. the whole of the cortex is involved. The lens becomes pearly white in colour
- Hyper mature senile cataract (HMSC)- May occur in any of the two forms
- Morgagnian hypermature cataract
- Sclerotic type hyper mature cataract