The slit lamp allows the orthoptist, through the use of a binocular microscope, to see a magnification of the front structure of the eye. this might be done for a patient with abnormalities of eyelids, conjunctiva, cornea, iris and lens. These abnormalities may be infections, foreign bodies or cataracts. in other words, this is an instruments, used in the treatment of eye diseases like cataract, myopia and other.