Researchers recently evaluated the effect of the size of the dots used in random-dot stereograms for measuring stereoacuity and found that size does matter.

The researchers made a measurement system with a phoropter and two smartphones that included 1x1, 6x6 and 10x10 pixel-dots. Random-dot arrays were formed, each with one Lea symbol hidden in it.

The researchers tested the three different dot sizes on 30 patients with normal acuity and stereoacuity. They found that stereoacuity measured with 1-pixel dots was significantly worse than stereoacuity measured with 6-pixel dots. There was no significant difference between 6-pixel dot and 10-pixel dot stereograms.

“The size of the dots in random-dot stereograms affects the test results significantly when the dots are too small for the eye to resolve,” the researchers concluded.

Zhao L and Wu H. The effect of dot size in random-dot stereograms on the results of stereoacuity measurements. BMC Ophthalmology. June 24, 2020. [Epub ahead of print]