I have farsightedness and using glass for 10 year but it still decreasing (begun with -1.5 , now -7 ) if it continue like this i gonna be blind? help

Probably not: If your numbers are in the minus (-) range, then you are nearsighted. This tends to progress through the mid 20's in age and then it stops changing. - 7.00 is moderately high but a long way from serious eyeglass need. In absence of other eye disease, you will not become blind from the advancement of your eyeglass power needs.

Keratoconus: I am concerned with the degree of nearsightedness (if your numbers are preceded by a "-") and would recommend your eye care professional evaluate you for keratoconus. This does not lead to blindness. Contact lenses will greatly improve your vision.