“How can short-sightedness be cured permanently?”

Cant do

"Short-sightedness" is another term for near-sightedness or myopia. There are several "refractive/eye" conditions including nearsightedness, farsightedness, astigmatism, and presbyopia. What you have is based on your eye's anatomy (the structure) and its physiology (its function). If you think of your eyes as a camera, people who have myopia see things clearly up close but things in the distance will be blurry. Your vision up close and in the distance may also be affected if there is any associated astigmatism which is very common.
Other factors that will determine your myopia may include age, medications, eye health, general health, and genetic issues.
Myopia is not a disease that can be cured. It is a condition that can be treated with glasses, contact lenses, or refractive surgery. None of these treatments are a permanent "cure", but each one will resolve your vision issues for a period of time until your eyes normally age and change. By placing eyeglass lenses or contact lenses in front of your eyes, things will be properly focused so that you can see at any distance.
I would suggest to you that you discuss your options with your eye doctor who diagnosed your myopia in order to determine which options are best for you. Good luck and best wishes.

Refractive surgery . I recommend LASIK