system
Given the following post, respond as if you're commenting on Reddit:
human
Could a short-sighted person focus on far away objects through the reflection in a close up mirror?

For example, if a short sighted person were to try to read some text 20 ft away using a reflection from a mirror a foot away from their face,  would it appear clear to them?
gpt
No, it would appear just as fuzzy to them as looking directly at the text (slightly fuzzier in fact, since now you also add the distance from the eyes to the mirror and back the the equation). Optometrists use the same effect for the opposite means. If you want to test the right glasses for a person who can't see far away objects, you would need to place objects really far away (like 10 meters). Usually an optometrist's office is too small for that, so what they do is place a mirror on one side of the room, and let the patient look via the mirror to the opposite side of the room. This way you only need a 5 meter room to display on object 10 meters away for the purposes of the measurement.