Ocular coherence tomography is a noninvasive scan of the internal structures of the eye. The OCT scan uses light beams to make detailed images of the layers of the retina which can detect eye problems such as age-related macular degeneration, retinal fluid, macular holes, or even optic nerve changes from glaucoma.
Retinal nerve fiber layer (RNFL) thickness analysis is important in assessing the damage from early glaucoma, as the RNFL has been shown to become thinner before other changes from glaucoma become evident. ?In the same way the OCT scans the layers of the retinal, the RNFL analyses the optic nerve layers to detect even the earliest changes from glaucoma.
Before these tests drops are instilled to dilate the pupils to enable a clearer view to the retina. During the test, light beams are focused onto the back of the eye showing a graph of the retinal layers or optic nerve structure on a computer screen. OCT or RNFL takes about 10 to 20 minutes.