The binocular indirect ophthalmoscope, or indirect ophthalmoscope, is an optical instrument worn on the examiner’s head, and sometimes attached to spectacles, that is used to inspect the fundus or back of the eye. It produces an stereoscopic image with between 2x and 5x magnification. It is valuable for diagnosis and treatment of retinal tears, holes, and detachments. The pupils must be fully dilated for it to work well.