How often to you have to renew your eyeglasses prescription?

It depends upon age of the person whose eyeglasses prescription is to be renewed. Generally eyeglasses prescriptions are to be renewed every two years.But those having retinal problems, they should be guided by Doctor's advice.There is a tendency among the teens that their eye powers go up at a rapid rate up to the age of l8 years, during which time their eyeglasses prescriptions should be renewed every year by their guardians.