The eye is a changing and evolving organ. If a person is far-sighted or near-sighted; their prescription changes over the years. Especially during puberty, the eye glasses used changes more often. There is not a “defined best age” to get laser eye surgery.
Lasik is not approved for people under 18 years in many countries unless there is an emergency. It is most commonly performed between ages 20 and 40 but advised by ophthalmologists after mid-twenties; once the eye prescription is stable for a few years.
There are few determining factors to have laser eye surgery. The cornea of the person should be suitable. The eyes should be in a good condition, not too dry from using too much contact lenses. The eye prescription should not be too low or too high. Your surgeon would inform you about the suitability of your eye but it is a very common procedure with very high success rates.
Key is to wait until your eye stabilizes at a certain degree, preferably 2 years. The second half of twenties are commonly preferred before the eyes start to change around 40. People with older age prefer mono-or-tri focal lenses where a lens is inserted into the eye and frees the patient from all eye-glasses.