Why did my vision drastically improve after cataract surgery?
Many people do not realize it, but “cataract” is just out-of-date terminology for the age-related degeneration of the eye’s internal, natural lens. That lens does have a “prescription” much like your glasses or contact lenses. A lens prescription is typically measured in units called “diopters.” Minus diopters correct nearsightedness and plus diopters correct farsightedness.
So, regardless of the degree of clouding of the natural lens, (what is still loosely called a “cataract”) -its replacement with a new, clear plastic lens implant offers the opportunity to change its prescription.
For example, you may be nearsighted with a glasses Rx of -3.00 D (diopters) and now you have a cataract developing. Your natural lens might have an Rx of +20.00 D. (a pretty normal value for most people). So if your eye surgeon replaces that cloudy lens with a +17.00 D lens implant (+20–3), your nearsightedness will largely be fixed along with the cataract.
This is a very simplified description, leaving out many important optical details, but is basically what can be done. Obviously, if your surgeon did this, you would never need LASIK!