Depends on the person. While you can see fine out of an old pair, I would say your vision Rx changes on a yearly basis.There is a big difference between ok vision and perfect vision. Some people can correct down to 20/10 vision, but ideally you'd like 20/20 vision. Most people won't notice if they are seeing 20/30 or worse. Also, if you have a lot of stress, your vision could see some significant changes in a short period of time.I would say most people see big vision changes when they are very young (ages 10 through 21) and it will stabilize a little until their lower 40s when presbyopia kicks in and you need bifocals. Just because you see fine out of your glasses doesn't mean you shouldn't go into a doctor for a yearly check up. Not only will he give you a new Rx for glasses, but he will also check on the health of your eyes. There are a lot of things an eye doc can pick up on before there are any physical or visual symptoms.
