Pediatrics journal in the USA reviews the evidence for interventions such as tinting the screen for people with various print impairments and finds the evidence wanting:
“Scientific evidence does not support the efficacy of eye exercises, behavioral vision therapy, or special tinted filters or lenses for improving the long-term educational performance in these complex pediatric neurocognitive conditions [e.g. dyslexia]. Diagnostic and treatment approaches that lack scientific evidence of efficacy, including eye exercises, behavioral vision therapy, or special tinted filters or lenses, are not endorsed and should not be recommended.” Pediatrics 2009;124:837–844
You can download the whole report from their website: Learning Disabilities, Dyslexia, and Vision.
It’s clear that strong assertions about the benefit of colour changes as yet lack scientific evidence. AT professionals will know, however, that many end-users report benefits from changing the colour scheme of their display: whether this is a placebo effect or some not-yet-understood mechanism, tinting tools have strong anecdotal support. Since they are fairly inexpensive and easy to use, there seems no reason to drop them from the arsenal of software useful for people with disabilities even being able to reduce contrast is not a panacea.