StrengthReading glasses typically range from +0.25 to +2.50 diopters (the unit of measurement for eye prescriptions), though the average starting strength is usually around +0.75. In rare cases, reading glass strength can go up to +4.00. “Tips for buying reading glasses online are similar to buying ready-made reading glasses at the drugstore: It’s a convenient option but it’s not a good idea for everyone,” says Dr. Ravi Goel, clinical spokesperson for the American Academy of Ophthalmology. “If you have different prescription needs in each eye, astigmatism, high-power or more complex prescription needs, you should see an eye care professional for updated…