Landolt ring

Landolt,

Edmund, French ophthalmologist, 1846-1926.
Landolt bodies - bipolar nerve cells lying between the retinal rods and cones in amphibia, reptiles, and birds.
Landolt circles
Landolt enucleation scissors
Landolt eye knife
Landolt eyelid reconstruction
Landolt keratome
Landolt operation
Landolt ring - instrument used for testing of visual acuity.

Landolt ring

A test object used for measuring visual acuity consisting of an incomplete ring resembling the letter C. The width of the break and of the ring are each one-fifth of its overall diameter. The subject must indicate where the break is located, the break being positioned in any direction. The minimum angle of resolution corresponds to the angular subtense of the just noticeable break at the eye (Fig. L3). Syn. Landolt broken ring; Landolt C; Landolt test type. See Landolt broken ring chart.
Fig. L3 Landolt ringenlarge picture
Fig. L3 Landolt ring
References in periodicals archive ?
There is a point where the visibility of a gap in a Landolt Ring and people's preference for lighting diverges.
Targets can be single letters, words, Landolt rings (Cs), or tumbling Es.