Self-diagnosis with a Mirror
When you're alone, you can still test your distant visual acuity using this app and a mirror.
After enabling the mirror mode for the Snellen, ETDRS, or Numbers Chart and selecting auto-scoring mode, stand approximately 1 meter in front of a mirror. This setup effectively creates a 2-meter test distance. Place your phone or tablet near one ear with the screen facing the mirror. To ensure only one eye is open during the test, you may cover the other eye with an eye patch.
You can also use the Tumbling E Chart, Landolt C Chart, and HOTV Chart naturally in front of a mirror. For example, if the "E" on the screen has limbs pointing to the right, its reflection in the mirror will appear to point left. In this case, swiping right on the screen marks a correct answer, and the mirrored action corresponds to swiping left in the reflection.