I cannot remember how long my mother has had her prescription eyeglasses. I don't really have any idea how long before you should change eyeglasses if you have one. I think that, over time, the condition of the eyes change and of course, you should also change eyeglasses according to your needs.
My mom has been complaining about her eyeglasses. I told my mom that she should have her eyes checked as soon as possible so she can have her eyeglasses adjusted. She was worrying about the cost. Well, there are affordable eyeglasses available everywhere. Nowadays you can even order prescription eyeglasses online.
To be able to order online, you just need to have a prescription for corrective eyeglass lenses and your pupillary distance.When you have your eyes examined, request your PD (Pupillary Distance) from the person performing your exam. Corrected lens eyeglasses cannot be made without it and knowing what your PD is gives you the power to order your prescription glasses anywhere you want.