Well, as we know that the cornea is the tissue on the very front of the eye. In common, cornea is clear and covers the iris and pupil. But when the cornea becomes swollen, or scarred, corneal transparent may be needed. And generally speaking, the surgery can be done in less than an hour and is virtually painless. On the other hand, it will be a long time for your eyes to recover. For example, it will take about one year to recover. And after the surgery, your eyes will be fragile, it is very important to protect your eyes from bacteria and also the eye strain. Anyway, just be careful about it.
One of my friends experienced the surgery, he told me that the surgery lasted no more than an hour. While, after the surgery, there are many points you should take care, and a corneal transplant do not last forever, which depends a lot on what makes you a candidate for cornea transplant in the first place.
Ok, I can see that you are curious about the details of the surgery. So as you can see it could greatly improve your vision and help you out of the risk of blindness. Anyway, on a general basis, the surgery would take about 3 hours or so. But it depends on your specific situation. And the preliminaries of the surgery could be quite lengthy sometimes. Just take it easy, they would inject anesthetic to you before the surgery.