Reading the answers from my previous response, I obviously didn't explain accurately. A cataract makes the lens go cloudy, and the lens has to be 'removed' (if it is not done, it would eventually be like trying to see through frosted glass). This is usually done by ultra-sound - it's called phacoemulsification, and an IOL is inserted. These are small (about 1/8th inch) and flexible (I was told they fold it in half to insert it through the small hole created when sucking out the remains of the natural lens).
I called the op 'minor' as the whole thing from when I walked into the hospital until I left to go home only took about 3 hours, during which I was awake the whole time, most of which was spent waiting for the anaethestic drops to become effective. The op itself took 20 minutes.
The lens inserted also adjusts my vision so I would not need glasses except I also have astigmatism which requires adjustment. I do need reading glasses, and was told that would be the case when I was assessed for the op.
A friend at my golf club had both eyes done within 3 weeks and he is astounded at how well he can see. Another friend's wife had both of hers done privately and again is very happy with the results.