Cataracts involve the lens of the eye which is located just back of the cornea.
The lens is composed of evenly aligned collagen fibers which are progressively damaged by ultraviolet light as we age. Cataracts cause clouding of the lens and reduce visual acuity, as well as causing a stiffening and rigidity of the lens which keeps it from changing shape for close-up activities like reading.
If you live long enough, cataracts are almost inevitable and the main decision is when to get them corrected. With intraocular lenses, the operation has few downsides.
The halo around oncoming headlights disturbed my night driving, and was a major reason for me to get my cataracts removed.
I used to require glasses all the time, and took them off to read. Now I wear no glasses, and even reading is possible without glasses, since one of my eyes has a -1.5 diopter cylindrical astigmatism. You can ask for one Intraocular lens to be slightly nearsighted, if you wish to avoid needing reading glasses.
I prefer to use my corrective glasses to read, however.