Eye chart with optotype letters

The C-Test is used to determine visual acuity and to test for crowding phenomenon (crowding effect; based on the C-Test for distance according to Haase/Hohmann) at distance.

Haase and Hohmann developed the first C-Test in 1982. The Landolt ring (standard optotype) is offered as an optotype in four different straight directions/orientations (openings: right, left, top, bottom).

If crowding difficulties are present, visual acuity decreases the closer the spacing between the optotypes. An irritating interaction of adjacent symbols occurs. Crowding difficulties have long been known in amblyopic subjects.

The result of the visual acuity test depends on the symbol size and symbol spacing.

By comparing the measurements of visual acuity with single optotypes and with row optotypes (printed as close together as real reading texts), the crowding ability when reading closely spaced optotypes is investigated.

The C-Test for distance to test for crowding difficulties is suitable for quantitatively detecting amblyopia, even of a milder degree.

Scope of delivery:
C-Test for distance to test for crowding difficulties, 2 vision test charts (made of Alu-Dibond) printed on both sides for a test distance of 5 m.
German and English labeling, visual acuity values decimal, LogMAR, real and equivalent values in meters and feet. Optotype Landolt ring;

1. Vision test chart:
Front side: Cover or protective side
Back side: Landolt rings (single optotypes)

2. Vision test chart:
Front side: Landolt rings (row optotypes, 17.6 arc minutes)
Back side: Landolt rings (row optotypes, 2.6 arc minutes)

3. Answer cards as table display:
Cellophaned on both sides with matte acetate film.
Dimensions: approx. 155 x 220 x 85 mm (H x W x D)

4. Instructions for use