Optical Coherence Tomography Imaging in Eye Care

Optical coherence tomography (OCT) is an imaging technology with growing applications in eye care. OCT is similar to an ultrasound in that this device takes multiple high resolution cross-sectional non-invasive scans of a particular tissue. However, OCT uses light rather than sound to take these cross- sections. The technology is quite versatile and can be used to gain additional eye health information that may otherwise be difficult or impossible to assess.

There are several common uses of the OCT in everyday practice. First, OCT can be used in assessing the optic nerve for signs of glaucoma. The assessment takes 400 cross- sectional images of the optic nerve in a matter of seconds. It then builds a 3D model of the nerve and takes multiple measurements of the nerve tissues in micro-meters. This allows for monitoring of even very minor structural changes.

When assessing a patient for glaucoma, there are many different things to evaluate, including the optic nerves, the pressure inside the eye, the side vision and corneal thickness. One of the biggest indicators of glaucoma is a change from one visit to another in any of these parameters. OCT gives very precise measurements of the optic nerve parameters, which allows accurate monitoring for any changes to detect and diagnose glaucoma as early as possible.

Secondly,   OCT   can   be   used   for assessing the macula. The macula is the central part of our retina responsible for 20/20 vision. This is the part of the eye affected by macular degeneration (AMD). The OCT is useful in managing and monitoring patients with the dry form of AMD; the OCT gives multiple retinal thickness measurements which can be used to assess the progression over time. In addition, the OCT images the layer below the retina where the wet form of AMD begins. Wet AMD causes most cases of severe vision loss associated with AMD. Fortunately, effective treatments are available for wet AMD when initiated as early as possible. In some cases, particularly

in occult types of wet AMD, the OCT can diagnose the wet AMD earlier than   conventional   assessment   or even the previous standard test called fluorescein angiography.1

The OCT is also very useful in patients with diabetes; it assesses the macula for swelling — one of the common ocular complications of diabetes. OCT allows precise thickness measurements of the retina and also allows viewing of the location and size of the fluid area buildup. Arrangements can then be made to administer treatment and monitor its effectiveness.

OCT is a new versatile non-invasive tool that has become a powerful addition to a routine eye examination when it is needed or indicated. The future will likely continue to bring additional uses for the OCT. For example, researchers are currently studying the use of OCT in measuring retinal ganglion cells to see how this may help in diagnosing or monitoring the progression of multiple sclerosis. The retinal nerve cells are projections of nerve fibres of the brain, so this may provide some amazing insights into this or other nerve/neurological diseases. Time will tell. Book an appointment today at 306.586.7036 to find out if this test is right for you.

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References 1. Spectral Domain Practical Guide. Decosta S et al. P188.

TOP Sample OCT image of a macular hole