Yes but I would recommend that you use the lower script so that you don't cause any deterioration in your vision.
The answer is no, as long as your eyes need the same prescription. The problem with OTC reading glasses is that they have the same prescription lens for each eye. Most people's eyes require different prescription strengths. You should go to the eye doctor to get a prescription, and then decide if OTC is good for you. See related link for myths about glasses.
I think you are safe.
I don't think it is OK to wear contact lenses if your eyes are not damaged because then you don't need them. All they will do is damage your eyes and when you are wearing them you wont be able to see because you need a prescription/its not the right prescription!
In order to get a prescription for glasses you need to see an Optometrist. They will examine your eyes and determine how powerful you glasses should be or even if you need glasses at all.
It all depends on the type of contacts and prescription of your eyes.
When you have had your eyes examined/tested, ask for a copy of the prescription.
You will have to find over the counter reading glasses that EXACTLY match your prescription. This may be easy if your prescription is only for spherical correction and is identical in both eyes. However if you have any astigmatism (cylindrical correction) or the prescription for your eyes differ, then you will have to stay with the prescription reading glasses as over the counter reading glasses are not intended to correct such problems.However even given what I said above, it still may be worth your time to get a pair of over the counter reading glasses even if you cannot exactly match the prescription as a backup pairshould something happen to your prescription ones. But make sure the spherical correction matches your prescription with no more error than half a diopter in each eye (especially if the eyes are different) and try them in the store before buying to make sure they seem OK and don't give you a headache or dizziness (if you have astigmatism).But remember that if the optometrist that wrote your reading glass prescription had felt that over the counter glasses were adequate for your needs he would have told you to just pick up a pair at the drugstore and given you a single number for the spherical correction you needed instead of spending the time to write a full optical prescription.
If you have trouble reading then yes non-prescription reading glasses would be beneficial to your eyes. You may also consider gettng your eyes examined by an eye doctor.
How Do I can onvert a vietnamese eyes glasses precrition to a US precription
As such there is no difference between the lenses as long as prescription is same for both the eyes. So in mostly both the eyes have same prescription. If there's a difference, then mark the case with some indicators to distinguish. When you are getting your contact lens prescription the first time, the eye doctor will mark the box for you if you have a different precription for each eye. L means the contact lens will go in the left eye and R will go in the right eye.
Strained eyes are generally caused by focusing too intensely. To treat strained eyes all you need to do is rest your eyes. The other treatment option is to use an eye lubricant.
Prescription sunglasses are just like regular prescription glasses except they have tint like sunglasses. It's so that people who have to wear glasses won't have to cover their eyes when it is really sunny outside. Instead, they have the luxury of wearing stylish sunglasses and being able to see with them.