Apparatus, systems and methods employing a contact lens having a pulse oximetry sensor to detect information indicative of a blood oxygen content and/or pulse rate of a wearer of the contact lens, are provided. In some aspects, a contact lens includes a substrate that forms at least part of a body of the contact lens and a pulse oximetry sensor located on or within the substrate that detects information associated with at least one of blood oxygen content or a pulse rate of a wearer of the contact lens. The pulse oximetry sensor comprises one or more light emitting diodes that illuminate a blood vessel of at least one of a region of an eye or an eyelid and a detector that receives light reflected from the blood vessel and generates the information.