What does a naked-eye vision of 1.0 mean?

Generally, uncorrected visual acuity of 1.0 is considered to indicate normal vision. If vision problems occur, it is recommended to seek medical attention promptly. The detailed analysis is as follows:

Uncorrected visual acuity of 1.0 is a standardized metric used to describe human visual capability. Uncorrected visual acuity refers to the level of visual clarity an individual can achieve without any vision-correcting aids. It is typically assessed using a standard eye chart, with results expressed as a numerical value—where 1.0 represents optimal vision. At this level, a person can clearly discern objects and fine details of standard size without needing glasses, contact lenses, or other visual correction devices.

An uncorrected visual acuity of 1.0 is generally regarded as normal visual function. However, variations in visual acuity are common, so not everyone can easily achieve 1.0 uncorrected vision. Some individuals may fall short of this standard due to myopia, hyperopia, astigmatism, or other refractive errors. Uncorrected visual acuity can also be influenced by genetic factors, age, environmental conditions, and the presence of eye diseases. Moderate use of the eyes in daily life helps maintain healthy vision.