Medical sensors assemblies with shielding elements are provided that may be applied to a sensor body to reduce ambient light infiltration. In one embodiment, the shielding elements may be applied only about a portion of the sensor body such that an additive pressure of the shielding element and the sensor body on the patients tissue is reduced. For example, the shielding element may include openings that reduce the total surface area of the sensor body that is covered by the shielding element. In addition, such shielding elements may be provided as separate accessories for a sensor that may be applied only when ambient light infiltration is detected.