Visual acuity light box

Definition

A mains electricity (AC-powered) light viewing box that uses a translucent version of the ophthalmic chart (Snellen chart) imprinted with block letters (optotypes) and/or other symbols (e.g., LEA symbols for children who can not read) in gradually decreasing sizes used for testing visual acuity. The letters/symbols are identified according to distances at which they are ordinarily visible (normally 6 metres or 20 feet) and are combined in a box where the individual letters or symbols are selected and high-lighted by the optician/doctor with background electrical lighting. This device is typically mounted on a wall of the optician/doctor's examination room/office.

GUDID devices

17

Last updated

2025-12-17 15:30:38