What is the standard for normal vision? What do 1.0 and 5.0 mean?

Standard for normal vision: On the decimal visual acuity chart, normal vision is generally 1.0 or above; on the logarithmic visual acuity chart, normal vision is 5.0 or above. A value of 1.0 means the human eye can clearly distinguish optotypes subtending a visual angle of one minute of arc, while 5.0 indicates good visual resolution ability.

The standard for normal vision is typically measured using either decimal or logarithmic visual acuity charts. On the decimal visual acuity chart, normal vision is generally considered to be 1.0 or higher. This means that at the standard testing distance, the human eye can clearly resolve optotypes subtending a one-minute angle of vision. The eye's refractive system and retina work together effectively to accurately focus external objects onto the retina, forming clear images. This level of vision adequately supports daily activities such as recognizing distant objects, reading text, and distinguishing object shapes and colors.

On the logarithmic visual acuity chart, normal vision is defined as 5.0 or higher, which corresponds to a decimal acuity of 1.0. It similarly indicates good visual resolution ability, allowing individuals to clearly identify optotypes of corresponding sizes under standardized testing conditions. Normal distance vision enables people to see fine details of objects from a distance, with no significant impact on everyday visual tasks such as reading, driving, or observing their surroundings.

It is recommended to maintain proper eye care, use eyes reasonably in daily life, and avoid prolonged use of electronic devices. Additionally, it is important to develop healthy lifestyle habits, ensure sufficient sleep, avoid staying up late, and maintain a positive mood, avoiding negative emotions such as anxiety and irritability, all of which contribute to overall health.