In the Pola mirror test, which statement accurately identifies suppression?

• A. The patient wears stereo glasses and stands in front of a mirror.
• B. The eye that turns black is the non-suppressing eye.
• C. The eye that turns black is the suppressing eye.
• D. Suppression is inferred from color changes in the mirror.

Answer: (C)

Suppression occurs when the brain blocks input from one eye to avoid double vision. In the Pola mirror test, each eye is presented with a different image through a setup that creates a dichoptic view using specialized glasses and a mirror. If an eye is suppressed, the image seen through that eye is perceived as black on the mirror, while the other eye’s image remains visible. Therefore, the eye whose image turns black is the suppressing eye. The test does not rely on color changes in the mirror to indicate suppression, and it is not simply about wearing stereo glasses in front of a mirror—the darkened (black) image identifies which eye is being suppressed.