Optical Coherence Tomography (OCT) in Diagnosis of Glaucoma

Optical Coherence Tomography (OCT) is a medical imaging technique in the diagnosis of eye diseases by doing optical sections in ocular tissues. The principle of OCT is based on analyzing the time of light delay of optical signals that have been reflected from ocular tissues such as the retina. Optical signals are analysed by high precision low coherence interferometry to produce optical sections in ocular tissues. These sections are analogous to cross sectional images of ultrasonography but using optical signals instead of sound waves with an axial resolution less than 10-20 μm. It has the advantage of being non invasive, non contact, comfortable and well tolerated by the patient. Measurements of retinal nerve fiber layer (NFL) thickness with OCT are potentially useful in the early detection of glaucomatous progression. Standard clinical techniques for assessing glaucomatous changes, such as optic nerve head (ONH) and nerve fiber layer (NFL) examination or visual field testing, lack sensitivity and reproducibility. The high longitudinal resolution of OCT enables direct measurement of nerve fiber layer thickness with micro scale resolution.