Optical coherence tomography is a disgnostic procedure in which a scanning light is used to create a digital cross-section image of the retina. The scanning light is aimed at the retina and a computer senses the amount of light reflected by the retina to create the cross-section image. This diagnostic test is used to view swelling, membranes, macular holes, and the optic nerve. In addition to viewing these conditions, the OCT is a great tool for diagnosing glaucoma. The thickness of the various retinal layers can also be easily displayed using OCT.

Compare the OCT image of a normal eye above, with that of an eye with a macular hole as shown below. The OCT image of the eye with a macular hole clearly shows the typical "tunnel" in the center of the macula which extends through many retinal layers. A normal macula has just a small dip as shown above.