Why does the VisionCheck App ask for the resolution to be set to maximum?

If you have an Android smartphone and can change the resolution of your screen, the VisionCheck app may ask you to raise your resolution to maximum if the current resolution is too low.  The resolution of your smartphone must be set to at least FHD.  This is because the DPI of the smartphone may be set under the required DPI of 250 in order to use the VisionCheck properly.  Once you have set the resolution of the smartphone to at least FHD, you must force close and restart the app for those changes to be recognized by the application.  If you do not, it will continue to give you this error and ask you to increase the resolution of your smartphone's screen.  Once you have done so, you will be able to use the VisionCheck app as normal.