‘弱视’ (ruò shì) literally means ‘weak vision’ — ‘弱’ (ruò) means ‘weak’ or ‘diminished’, and ‘视’ (shì) means ‘vision’ or ‘sight’. It is the standard medical term for amblyopia, a neurodevelopmental condition where the brain fails to fully process visual input from one eye, leading to reduced visual acuity despite no structural abnormality in the eye itself. Often called ‘lazy eye’ in informal English, it typically develops in early childhood and is not correctable with glasses alone.

This term is used exclusively in clinical, educational, and health-related contexts — for example, during pediatric eye exams, school vision screenings, or discussions about early intervention. It is not used for temporary blurry vision, age-related decline, or refractive errors like nearsightedness. Early detection and treatment (e.g., patching the stronger eye) are critical, especially before age eight, when neural plasticity is highest.