An indirect ophthalmoscope is an instrument commonly used for eye examination, usually consisting of a light source and an imaging system. The light source emits a beam of visible or infrared light to the fundus of the eye, and the imaging system generates a fundus image by receiving the reflected light signal. One of the routine ophthalmic examination methods is to enlarge the fine structure of the eye so that doctors can more clearly observe the patient’s fundus lesions.
Unlike direct ophthalmoscopes, the imaging system of indirect ophthalmoscopes consists of a front lens. The eye inspector generally holds the front lens in front of the subject’s eyes. The light reflected from the fundus of the examined eye first passes through the front lens to form an enlarged inverted real image, and then the enlarged real image is attached to the sensor through the imaging lens.