How do you know if you need glasses?

The reason people miss the need is that vision deteriorates slowly enough for the brain to compensate, so the change registers as fatigue rather than blur. The signals worth acting on: squinting to resolve text or signs, headaches that appear after reading or screen work rather than randomly, holding a phone or menu farther away than you used to, difficulty with road signs or oncoming headlights at night, losing your place while reading, and eyes that feel tired and heavy by late afternoon. Children may show different signs, including sitting close to screens, covering one eye, avoiding reading, or unexplained trouble in school.

A few clarifications about what an exam covers. Presbyopia, the age-related loss of near focus that begins around 40, is universal and unrelated to whether you needed glasses before. A comprehensive eye exam also screens for glaucoma, diabetic retinopathy, macular degeneration, and other conditions that are asymptomatic until damage is done, which is the stronger reason to go on schedule rather than waiting for symptoms. Adults with no risk factors are generally advised to have exams every one to two years, more often with diabetes, family history, or existing correction. Online vision tests measure refraction only and do not screen for disease. Two persistent myths worth discarding: reading in dim light and sitting close to screens cause eye strain but do not cause permanent damage, and wearing glasses does not weaken your eyes or create dependence.