What does "OS 20/40 sc" signify in distance vision measurement?

"OS 20/40 sc" denotes a specific measurement in visual acuity for the left eye (indicated by "OS," which stands for "oculus sinister"). The notation "20/40" indicates that the individual can see at 20 feet what a person with normal vision (20/20) can see at 40 feet. This measurement means the person's vision in the left eye is less sharp compared to what is considered "normal" vision.

The designation "sc" stands for "without correction," indicating that this measurement was taken without the aid of corrective lenses. Hence, the interpretation of this notation helps eye care professionals assess the individual's visual capabilities and determine if corrective measures, such as glasses or contact lenses, are necessary for improved distance vision.

In contrast, the other options do not accurately represent the meaning of "OS 20/40 sc." For instance, mentioning the right eye, normal vision status, or the inability to see beyond 20 feet would not correctly describe the significance of this specific visual acuity measurement for the left eye. This highlights the importance of understanding ocular measurements properly for effective patient care and the evaluation of visual health.