What visual acuity result indicates a need for further evaluation using the Snellen eye chart?

A visual acuity result of 20/30 in one eye and 20/40 in the other eye indicates a need for further evaluation. This combination suggests that the subject's vision is below the standard of 20/20, which is considered normal visual acuity. The Snellen eye chart is utilized to measure how well a person can see at a distance compared to a person with normal vision. When someone's visual acuity is not within normal parameters, such as in this scenario where both eyes are not achieving 20/20, it typically prompts further investigation to identify potential underlying issues that could be affecting vision.

In contrast, results such as 20/20 in both eyes reflect normal vision and do not necessitate further evaluation. An outcome of 20/25 still indicates relatively good vision and would not usually require additional assessment. Additionally, while 20/50 suggests a degree of vision impairment, depending on context, it might not trigger the same immediate need for follow-up evaluation as the combination seen in the questioned result, which displays significant variability between the eyes. Therefore, the result indicating a clear deviation from normal vision that warrants further examination is the combination of 20/30 in the left eye and 20/40 in the right