Instruct: Classify Amazon reviews into positive or negative sentiment
Query: If it sounds too good to be true - it probably is...

If you're wondering if this method really works, please search the literature (try Pubmed). I guarantee that you will not find a single well-designed scientific study that shows even an ounce of proof that this works. While you're at it, search for papers that prove that glasses and contacts harm your vision.Optometrists and ophthalmologists are not just trying to make money off of you by prescribing glasses and contacts. Withholding information or treatment that would benefit you would go against medical ethics. Take these reviews with a (large) grain of salt.