The slit lamp is basically a microscope. It has a light source with variable beam width and intensity with which the ophthalmologist can examine your eyes in magnification.
This instrument is mainly used to check the front part of the eye such as the cornea, the iris and the lens.
Using special lenses we can also look into the vitreous and the back of the eye, the retina.
The ophthalmologist sits on one side of the slit lamp and the patient on the other. It is possible to use special lenses that are placed in front or onto the eye in order to examine the posterior segment of the eye such as the vitreous, the optic nerve and the retina.