Slit lamp living microscope, referred to as slit lamp, is a common optical instrument in Ophthalmology, which is composed of light source projection system and optical amplification system. It uses a concentrated light source to illuminate the examination site, and then presents a strong contrast with the dark surrounding part. In combination with the binocular microscope magnifier, it can not only make the superficial lesions very clear, but also form a series of "optical sections" through the transparent tissue of each part of the eyeball by using the narrow light band, so as to make the different levels of refractive stroma and even the deep tissue tiny The lesions were also clearly shown. Under the magnification of binocular microscope, the target has a stereoscopic sense, which increases the accuracy of inspection. Therefore, slit lamp examination plays an important role in the clinical work of Ophthalmology.