FOGGING TEST

The fogging test đź‘€ is a clever way to uncover malingering (faking vision loss in one eye).

How it works

  1. Patient wears trial frame with +5.00 D lens over the “good” eye (blurs vision).
  2. Read the chart with “bad” eye (you’re checking if they can see better than claimed).
  3. If they suddenly read smaller lines, they’re likely malingering (using the “bad” eye all along).

Sneaky part

  • They think the “good” eye is being tested (because it’s fogged).
  • If they see better with the “bad” eye, it proves vision is actually better than claimed.

Tips

  • Don’t tip them off → act like you’re testing the “good” eye.
  • Quick switch lenses if needed to confirm findings.
  • Combine with other tests (e.g., stereoacuity) for stronger evidence.

Example

  • “Test” right eye (fogged with +5 D). Patient reads 20/20 with left eye → suggests left eye is actually seeing fine (malingering?).

Limitations

  • Not foolproof → some patients catch on.
  • Cooperation needed → won’t work if they refuse to read.