That’s why they usually wait until the mid 20’s at least to make sure the vision is stable and not changing anymore, but there are never any guarantees that it won’t change at some future time.
References :
Optician

1) presbyopia. lasik has never & will never treat this. *E-V-E-R-Y-O-N-E* over 45 W-I-L-L need reading glasses to see up close. it is going to happen. loads of people falsely believe (or have heard etc) that once you have lasik you’re done & you’ll never need any form of vision correction ever again…but they’re wrong. you’ll lose the ability to focus in your early 40’s and you will need reading glasses (or reading contacts, etc)

2) regression: some nearsighted people get nearsighted again. usually its b/c they weren’t "done" getting nearsighted in the 1st place & they got lasik anyway, or someone thought they were stable but they actually weren’t

as a point of clarification: neither of those makes a person "blind". big difference between "blindness" & refractive error
References :
optometrist
http://myeyepod.blogspot.com/