4. I have heard of “phacoemulsification surgery” for
    cataracts. What is it?

"Phacoemulsification" refers to a modern and advanced technique to remove a cataract.
Basically, the central part of the human lens, called the nucleus, is relatively hard and cannot be removed by simple suction liking drinking a Cola through a straw.
Therefore in the past, the surgeon would have to make a large opening and then "squeeze out" the nucleus. Having a large opening has several disadvantages. The eye can suddenly bleed profusely during surgery and become blind. A large opening means a the potential for large amounts of astigmatism, and it is the rare patient undergoing this old type of surgery that can have good eyesight without wearing glasses after the surgery.

In phacomulsification, the surgeon delivers ultrasound energy through a small probe. The ultrasound energy will convert the hard nucleus into millions of small particles – thus the term “emulsification”. The entire surgery can now be carried out with a very small opening. Visual recovery is relatively faster and patient has less astigmatism. A lot more patients who have undergone phacoemulsification can walk around without the use of eyeglasses.