Freiburg Vision Test  ‘FrACT’
by Prof. Michael Bach – Checklist

This is free software. There is no warranty for anything.

To achieve high-quality results you will have to be knowledgeable in sensory testing and want to observe the following

Calibration to the screen resolution (mandatory)

Enter the length of the blue ruler on the Settings screen (in millimeters); or use the plastic-card method (FrACT₁₀). This is automatically saved and needs only to be repeated when changing screens or resolution.

Important: Don’t change the zoom level of your operating system or the browser after calibration! Best re-check with the plastic card – you can detect zoom changes of ×1.5 at one glance.

Distance observer–screen (mandatory)

Enter in Settings (in centimeters, but there’s a conversion to inch), and be sure it’s large enough to avoid ceiling effects, see the Manual (FrACT₁₀ or FrACTclassic-PDF) on this. “max possible acuity” / “min possible LogMAR” must be better than your desired best acuity. This setting is automatically saved.

Luminance of the visual display unit (mandatory)

DIN and ISO norms prescribe the range 80–320 cd/m², easy to achieve with current display units; most cases: set to maximum.

Luminance of the surround (mandatory)

The surround requirements depend on screen size. If screen ≥ 10°: not darker than 1% of the screen; for smaller screens: between 10% and 25% of screen luminance.

Luminance linearity of your visual display unit (optional for acuity, mandatory for contrast)
Semiautomatic export of results → spreadsheet (optional)

More export options in the FrACT₁₀ Manual.

Remote keypad for response entry (suggestion)
Switch off keyboard repeat (suggestion)

This avoids unwanted responses, caused by prolonged pressing of a key. Use your operating system’s keyboard options to do this.

Start with a binocular training run (suggestion)

Running a binocular training run with your prticipants has proven useful. They can familiarise themselves with the test, and you can explain the “forced choice” situation, e.g.: “use your best guess, even if you don’t see it!” Usually, I don’t even analyse the results of this run.

“Whoops, pressed the wrong key”

When the subject reports “whoops, pressed the wrong key” during the first 3 trials: It’s best to abort by pressing “5” twice and restart this run.


Much more detail here: FrACT₁₀ Manual or FrACTclassic Manual [PDF].