What is 0.4 for eyesight?

In the context of eyesight, a measurement of 0.4 typically refers to visual acuity, which is a way to express how well a person can see. This measurement indicates that the individual's vision is below the standard level of 1.0 (or 20/20 vision), suggesting they may have difficulty seeing objects clearly at a distance. It's important for individuals with a visual acuity of 0.4 to consult an eye care professional for potential corrective measures.