You should not worry with - 2.25 myopic power & basically myopic power increases with body growth & in male body growth gets completed by 21 yrs of age , so now there is minimal  chance of increase in your myopic power & upto -3 D is considered to be normal & after 40 yrs there is lots of advantage of being myopic, with regards

There is no medication or food for improving eyesight or to get rid of glasses. If not interested in glasses then you can try a. Contact lens b. Lasik laser as your age is now 20 years so your number will not increase now whether you wear glasses or not as number becomes stable at age of 18-20 yrs. Having said that I advise you to eat balanced diet including green vegetables and seasonal fruits for keeping eyes and body healthy. If you are not comfortable with contact lens then go for lasik. Lasik is a very easy and painless procedure. If you want to get rid of glasses then go for lasik