B. According to the consistency of lens:
I. Soft cataract: Both cortex and nucleus are soft. So that:
- The whole lens can be completely aspirated during surgical removal.
- The lens can be lensectomized using the vitrectomy machine.
- Lens matter can be aspirated spontaneously by the aqueous if the lens capsule is injured.
* It is any cataract before the age of 20 - 30 years (it can be congenital, traumatic or complicated, but never senile cataract).
II. Hard cataract: The nucleus is hard due to the normal progressive decrease of water content of the nucleus during age. The hard nucleus can not be aspirated surgically, lensectomized or dissolved by the aqueous.
* It is any cataract after the age of 20 - 30 years (it can be senile, traumatic or complicated, but never congenital).