The Frisby Near Stereo Test has 3 plates of different thicknesses, providing stereo acuity measurements in the range 600-5 sec arc. They are stored in a box with a fold-down flap that provides a clear background. A tape measure is provided for controlling eye-to-plate distance.
First launched in 1983, it is used in orthoptic and ophthalmic clinics and by optometrists world-wide.
Tests for stereopsis using natural vision, with no special glasses. It has three transparent plates, which are presented to the patient one at a time against the clear background provided by the fold-down flap of the storage box.
Tests for stereopsis, even if reduced vision or amblyopia is present because of the coarse texture elements included in the pattern.
The plate is shown a few cm or inches above a clear background, such as the fold-down flap on the box as shown here. Note the tape is fixed to the flap for measuring and controlling eye-to-plate distance.
Frisby Stereo Test - 3 plates