What is OCT Scanning? (Optical Coherence Tomography)


In our practices we use high definition Optical Coherence Tomography (or OCT) Scanning to obtain images of the structures of the eye which previously we were unable to see by conventional means. The OCT is non-invasive and does not usually require dilating drops. From the patient’s point of view all that is required is to keep their eye still while looking at a fixation light inside the machine. The OCT can image the deeper layers of the retina beneath the surface where the early stages of macular degeneration and disease start. The earlier the disease is detected, the sooner it can be treated and the better the visual outcome. This OCT scan of a normal retina clearly shows all the layers to be healthy. In this image, the jelly or vitreous in front of the retina is pulling away from it, apart from at the central macular region. This is called vitreomacular adhesion. In these next two OCT scans, the vitreous has moved foward further still taking part of the retina with it. This is called a macular hole and results in very poor vision. It is possible to treat vitreomacular traction surgically, to prevent macular hole formation. This 3D scan shows a blister of intraretinal fluid, that has occured following cataract surgury. The location of the fluid is shown clearly on the 2D OCT section. We treated this condition with steroid eye drops, until a normal retinal profile returned. This patient, shown in the next two images has developed a epiretinal membrane on the retinal surface. As the membrane contracts, it causes distortion and cysts of fluid to form. This requires urgent surgical intervention. In wet macular degeneration, unwanted blood vessels grow into the retina, from the deeper choroidal layers. These unwanted blood vessels can hemorrhage and leak fluid into the retina. This can result in massive visual loss if left untreated. The watery fluid inside the eye drains away at a point where the front of the eye or cornea, meets the iris or coloured part. If the gap between these two structures gets too narrow, acute Glaucoma results. If spotted early, simple laser treatment can prevent the disease. In Glaucoma, the transparent nerve fibers that take the visual signal to the brain atrophy away. The OCT scan can visualize the thickness of this transparent nerve fiber layer and so atrophy can be detected early. Glaucoma caught in the early stages can usually be treated by taking a suitable eye drop to lower the pressure in the eye and prevent further damage to the optic nerve. We believe that all patients over 60 years of age and those in high risk groups should have an OCT scan regularly – at least every two years. Thank you for watching our video on OCT scanning a technology that has revolutionized the diagnosis and the treatment of many eye diseases.

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