- The app should be used in-door with moderate environmental lighting and quiet environment.
- The screen brightness of the device should be around 50% to ensure moderate illuminance of the application.
- The screen should be clean.
This app can remember its own brightness required. Got to the app's Settings/Brightness and set brightness independent of your mobile device's brightness. This app is generally for viewing from a distance longer than arm's reach, thus brighter white background is reasonable.
Voice Hint and Headphone
When Voice Hint is on, the app speaks what shown in current chart. So the "doctor" will know what shown on the screen when observing the responses from the "patient". This is particularly useful for Tumbling E Chart and Landolt C Chart while the responses may not be oral but gestural. However, the "patient" may hear the hint as well, so it would be nice that the "doctor" would wear a headphone connecting to the device.