Optical coherence tomography
Should you have an OCT scan as part of your comprehensive eye test?
Optical coherence tomography or OCT is a medical imaging technique that uses visible light to produce a 3-D image of what’s happening beneath the surface. MRI, CT-scans and x-rays are imaging techniques that use radiation, which can pose health risks, especially if repeated over time. OCT is more like ultrasound, only it uses visible light (rather than sound) and provides much higher resolution. It is safe to use as often as you like without risk to the eye’s delicate tissues.
Some eye disorders cannot be visualised with the naked eye. The normal viewing or photography that takes place during a comprehensive eye examination does not show what’s happening under the surface. To see what’s really going on, we can use Optical Coherence Tomography. It allows us to image the underlying layers of the eye in a non-invasive way. This is invaluable for picking up problems with the retina and macula as well as diagnosing and monitoring the progress of progressive diseases such as glaucoma.
How does OCT work?
OCT uses light from the red end of the spectrum (close to infra-red). This light has a long wavelength and this property allows it to penetrate the light-scattering tissues of the eye (and other organs). These tissues are not transparent (like the cornea and lens of the eye, which allow all visible light to pass through). But tissues such as retina and skin are semi-translucent, and allow some light to penetrate. The long-wavelength light that is used in OCT is bounced back in different directions depending on what it comes up against. This pattern of scatter is used to build up a cross-section picture of what lies beneath. (Ultrasound uses sound waves in a similar way).
What is OCT used for?
Over the past decade, OCT has been used primarily in ophthalmology and optometry for viewing the underlying structures of the eye. This technology is used routinely in the diagnosis and monitoring of glaucoma. It allows the profile of the optic nerve to be mapped out. This information is stored in the device’s computer so it can be compared to future scans to see if the disease is progressing or stable. Nothing gives a picture of what’s going on in your eye quite like an OCT image. That’s why The Eye Practice routinely performs this test as part of their comprehensive eye examination. We firmly believe that ‘an ounce of prevention is worth a pound of cure.’
Some eye conditions that are diagnosed / monitored using OCT:
- Retinal tear
- Retinal detachment
- Macular hole
- Macular pucker
- Macular edema
- Age-related macular degeneration
- Central serous retinopathy
- Diabetic retinopathy
- Pre-retinal membrane
- Choroidal melanoma
- Vitreous detachment
- Optic Neuritis
More recently, OCT has been used in other areas of the body including dermatology and cardiology for diagnosing skin and heart diseases.
Want more technical information on OCT? Click here.