Color Test is a Cassiopeia-authorized port of the Ishihara test for color vision deficiencies ("color blindness") popular with vision specialists and laypeople alike. The iPhone version of this application has been used and recommended by many doctors across many fields.
Please email the developer with any problems. Simply clicking one star in the comments does not help anyone solve anything for the future. Please send an email with your device specifics and what actions caused the problem. Thank you!