Thanks to everyone for the detailed information.
And that is great that an eye doctor also answered this.
By this oportunity i also wanna ask something about lasik.Before reading this posts, i thougt that lasik was the best solution, because no lenses, no glasses so no problem, and saying to my firends i would go for it.But we also had some discussions with my friends about lasik.And one said "have ever seen a eye doctor who had a lasik operation to him/herself?" and what i realised was , almost all doctors i saw were with glasses.And we continued to disscus the reasons.And one said, because it is a new technique, the long time effects,(mean when u get old) are not known. So after these words i had some doubts about doing it.Your answer also cleared my mind but i wanted to learn about these claims, from a professional.