Source: National Eye Institute, U.S. National Institutes of Health. Available online: http://www.nei.nih.gov

During a slit lamp examination, a doctor uses an instrument that provides a magnified, three-dimensional (3-D) view of the different parts of your eye. The slit lamp lets the doctor see the front parts of the eye, including the clear, outer covering (cornea); the lens; the colored part (iris); and the front section of the gel-like fluid (vitreous gel) that fills the large space in the middle of the eye. This helps find damage to structures of the eye and eye diseases.

Special lenses can be placed between the slit lamp and the cornea (or directly on the cornea) to view deeper structures of the eye, such as the optic nerve and the area where fluid drains out of the eye (drainage angle). A camera may be attached to the slit lamp to take pictures of different parts of the eye.