How long has the patient been reading when their vision gets blurry?

The correct choice for how long the patient has been reading when their vision starts to get blurry is after 2+ hours of reading.

This duration aligns with common experiences related to visual fatigue or eye strain, particularly during prolonged reading sessions. Typically, symptoms such as blurry vision, discomfort, or eye fatigue can emerge after extended periods of focusing on a task, particularly when one is reading or using screens. Two hours is a common threshold where people may begin to notice these effects, particularly if they haven't taken breaks or followed proper eye care practices. Most visual professionals recommend taking regular breaks, often suggested as the 20-20-20 rule: every 20 minutes, look at something 20 feet away for at least 20 seconds to help alleviate eye strain. Reading for two hours without breaks can lead to significant fatigue in the eye muscles, thus causing blurry vision.