A slit lamp is an ophthalmic microscope that allows the doctor to view many areas of the eyeball at a high level of magnification.

The slit lamp is one of the most common instruments in an eye doctor’s office.

The slit-lamp got its name from its ability to project a narrow, slit of light over the structures in the eyeball. This narrow slit enables the doctor to visualize an optical “cross-section” of multi-layered features within the eye. It is used by all eye care professionals to detect and even diagnose eye conditions. It can be used to image almost any part of the eye, from the front where the eyelids are, to all the way in the back, inside of the eye where the vitreous, retina and optic nerve is.

To image the inside of the eye, the ophthalmologist may use special, high-magnification, handheld lenses to increase the power of the slit-lamp microscopes level of magnification. These special lenses can also be used to look into the front angle of the eye in order to detect glaucoma complications, abnormal blood vessels or lesions.

When being examined with a slit-lamp, the patient will place their chin on a chin rest and lean their forehead into a headrest. The patient will see a bright beam of light moving as the doctor scans back an forth, moving from the front anterior portion of the eye, to the back. The light is bright, but not too uncomfortable. Some slit-lamps may also be used to check the intraocular pressure inside the eye.

A camera can be attached to this microscope, allowing the doctor to photograph and document eye diseases and conditions.

Most eye laser systems use a slit lamp for aiming and focusing the light from the laser.

The slit-lamp microscope is perhaps the most common and valuable tool for eye conditions and disease detection and diagnoses.