I Have Lost At Least 1/2 Of My Hair Following

I have lost at least 1/2 of my hair following a cataract surgery using versed. it is 1 and 1/2 year and my top scalp looks awful. I did get some of the natural curl back, and am taking vitamins. however how long before my fullness will come back? especially on the crown of the head. what can I do? thank you