Which of the following is a disqualifying vision condition?

Monocular vision refers to having vision in one eye only, which is a condition that can lead to disqualification for certain tasks, especially those requiring depth perception and a wide field of view, such as driving a commercial vehicle. Many regulatory standards, including those from the Department of Transportation (DOT), require individuals to have binocular vision—meaning they can see well with both eyes—to pass their medical exam. This requirement ensures that the driver can accurately judge distances and perceive their surroundings effectively, which is critical for maintaining safety on the road.

In contrast, the use of contact lenses is not a disqualifying condition as long as the individual's vision meets the required standards. Likewise, having 20/30 vision is generally acceptable for most driving tasks, since it indicates that the person can see adequately. Color vision deficiency, while it may impact certain specific tasks, is not universally disqualifying for all driving scenarios. Thus, among the choices, monocular vision is specifically disqualifying due to the potential safety concerns it raises.