If it worked,,,,,,why couldn't it be used as an aid ? god knows how many pilots need glasses as an aid.
Glasses that correct refractive errors are different from glasses containing color filters. The former type of glasses does not remove information from visual input, whereas the latter does. This means that, while glasses that correct refractive errors do not reduce the information available to a pilot but merely reformat it, glasses that "correct" color deficiencies actually provide a pilot with less information, and from a mathematical standpoint this means that color filters can only be useful in certain very specific circumstances, while they may be more of a hindrance than a help in all other circumstances.
For example, suppose you wear filters that selectively pass red light but filter out a lot of green and blue. With filters like these, red light will seem brighter to a person with deuteranomaly (red-green deficiency), making it much easier to distinguish from green. However, since so much green and blue is being removed from vision, the total amount of information reaching the eyes will be reduced, and blue and green lights will be much harder to see. In very specific circumstances that require only enhanced perception of red, the filters might be useful, but in most other circumstances they'd only make things worse.
Thus, a set of glasses that makes it easier to pass the Ishihara plates under a given type of light might work well for that specific situation, but might make things a lot worse under other types of light, and might make overall color vision in any other circumstances than an Ishihara test considerably worse.
This is why colored glasses aren't allowed for aviation. They only change things under very specific circumstances, enhancing perception for those circumstances at the expense of making things worse in all other circumstances. This is different from glasses that correct refractive errors, which do not remove information from visual perception but simply transform it (although the transformation may be one that also works best in certain circumtances).
The difficulty is in finding a set of color filters that would consistently improve color distinction for color-deficient individuals under a wide variety of flying conditions and for a wide variety of color deficiencies. While refractive errors are common and much research has gone into solving this type of problem, almost no effort has been made to try to compensate for color deficiencies in the same way (CVD being much less common than refractive errors). And while glasses can make a blurry image sharp, effectively providing more information rather than less, filtered glasses always remove information, so they may enhance certain differences but the overall image quality is always diminished.
Also, since filtered glasses always remove part of the light reaching the eyes, they greatly diminish night vision, whereas ordinary glasses don't (the light waves are redirected, but there's no reduction in light intensity).