This refers to examination of the eye with a slit-lamp, which directs a slit of light at the eye, which is inspected with a binocular microscope.
The slit-lamp allows alteration of the length, width and angle of the slit as well as the color of the light. It is also possible to adjust the magnification.
The slit-lamp can be used to examine both the front and the back of the eye.
A contact lens known as a gonioscope makes it possible to examine the anterior chamber angle, which is where aqueous fluid drains from the eye through the trabecular meshwork.
Various types of lens permit examination of the back of the eye, to assess the retina, vitreous gel and choroid.
The slit-lamp can also be used to administer various forms of phototherapy, such as transpupillary thermotherapy.