The use of minus lenses in low vision is primarily in which device?

• A. Monocular telescopes
• B. Reverse field telescopes
• C. Handheld magnifiers
• D. Pinhole glasses

Answer: (B)

Minus lenses (concave lenses) are used in low-vision devices to widen the field of view rather than to magnify. The device that primarily employs this approach is the reverse field telescope. By using a telescope optics in reverse and incorporating a concave lens, the system reduces magnification and expands the visible field, which helps someone with central vision loss scan text or scenes more broadly and navigate more easily.

Monocular telescopes and handheld magnifiers rely on positive lenses to enlarge images, not widen the field. Pinhole glasses work by increasing depth of field and reducing blur through a small aperture, not by using minus lenses.