“How do you know what strength reading glasses to get?”

Having an eye exam will give you a more exact answer to the strength of reader a patient needs. If a patient needs an over the counter pair in a pinch, select the lowest power reader (usually on the temple of the glasses) that makes a cell phone clear/comfortable.

Although the strength of reading glasses varies with age and refractive state of the eyes it is still best to try the proposed Rx in a doctor office.

The answer is that you should have an exam, and the doctor will be able to tell you what strength to get. In general its the least amount you can get away with. In reality on 5% of the population have both eyes exactly the same. By Law OTC readers have to be the same. That means they are not really correct for 95% of the population. In addition when glasses are made properly we make sure the centers of the lenses line up with the center of your eyes. In this way it does not give you any additional stress, nor can they make you addicted to them. When you buy OTC glasses, the centers are not standard, and can be anywhere. On top of that they use inferior quality lenses, that are not as clear as Prescription made lenses. They are meant to be any port in a storm, to read a menu here and there. They are not meant to be your usual everyday working or reading glasses. There is no substitute for the yearly Eye Exam.

When you have an eye exam, the refraction measures this with precision.

Your doctor work determine for you.