Cataract can be broadly classified into two categories-
• Age related
• Non- age related
Age related cataract
There are three types of cataract which may occur in older age. It is classified on the basis of its position on lens.
1) Nuclear cataract
This is the most common type of cataract. It begins from the center of the lens called nucleus. There is gradual hardening of the lens due to condensation and yellowing of the center of lens due to deposition of brown pigment within the lens. Due to development of opacity in the center it interferes with the vision.
2) Cortical cataract
It begins with white streaks on rim of the lens and move toward the center of lens. This occurs when change in water content in periphery of lens cause fissuring. Patients often face problem with glare and it causes halo effect.
3) Posterior cataract
It spreads very rapidly. Lens at the back becomes cloudy and causes blurred vision. It is mostly seen in patients having diabetes.
Non-Age Related Cataract
Non-age related cataract can be caused either due to genetic disorder, injury or medications. It can be classified as follows:
1) Congenital cataract
They are present right from the birth or in some cases it develops in childhood. It is caused due to alteration in chromosomes or due to some infection.
2) Radiation cataract
Cataract may develop due to exposure to radiation. It can damage the lens and the lens proteins.
3) Secondary cataract
It may develop due to eye injury or due to surgery for some other eye disease.