The Singapore General Hospital (SGH) has cautioned the public not to be misled by a fake YouTube advertisement for an eye product that falsely uses its logo.In a Facebook post on Thursday (Nov 12), SGH shared two screenshots of the advertisement, which shows what appears to be an ophthalmologist applying eye drops into a patient’s eye.The product's brand is unclear, but the advertisement claims it can correct vision by "0.5 everyday" without sur…