Created an account because I am a medical device engineer. You're mischaracterizing 510ks quite a bit. A 510k states that a new device has the same medical indi

Created an account because I am a medical device engineer. You're mischaracterizing 510ks quite a bit. A 510k states that a new device has the same medical indication as a previous device, and you don't have to demonstrate efficacy via clinical trials. In this case the medical indication would be "corrects vision." The darkening is a new feature that is not likely a medical indication. Regarding safety: You absolutely have to show safety. Any new material, additive, or processing chemical used for an existing indication must be demonstrated to be safe. This also applies if a currently used material is used in larger quantity, or used in a more serious degree of contact (longer duration, more invasive). This is done through biocompatibility testing in accordance with ISO 10993.