A method for optoacoustic imaging of a tissue mass after treating the skin overlying a portion of a tissue being imaged to improve optical clarity is presented. In an embodiment, the method involves optoacoustic imaging after first applying a carrier agent such as hyaluronic acid to the skin surface and applying a clearing agent to the skin. A method of temporarily reducing optical scattering (opacity) of skin for diagnostic purposes is also presented. In an embodiment, the method involves applying a liquid comprising at least one of: polyethylene glycol and polypropylene glycol, to the skin, the skin having been pretreated with hyaluronic acid.