What is OCT?
Ocular Coherence Tomography is similar to an ultrasound scan but uses light rather than sound to look through the layers of the retina, giving us a 3D view of the inside of your eye. When an optometrist looks inside your eye in a standard examination they can see the surface of the retina, but with an OCT scan we can literally see through the surface into the layers beneath. This tells us so much more and can help prevent loss of vision if changes are spotted early.
This is very useful for identifying early signs of macular degeneration and glaucoma, but also shows other changes happening beneath the surface of the retina, some of which are natural age related changes. If they are not expected, the scan helps us decide if treatment is necessary to prevent future loss of vision. This can be truly sight saving in some cases. Also, as a result of having more information, we can make an informed judgement about whether or not to refer. This can save people unnecessary hospital visits.
OCT screening also includes retinal photographs, sometimes referred to as fundus photography. This allows us to see a large area of the retina in one image, and aids comparison from one eye examination to the next.
If you opt for an OCT screening, our optometrists will show you the images of your eye and discuss any areas of interest.
Both of these scans together provide us with an exact and permanent record of the back of your eye. Building up a set of images over a period of time gives us a clearer view of any changes taking place, and helps us understand what is normal for your eyes.
Considering all the above, it is hardly surprising that optometrists recommend everybody should have an OCT scan and retinal photograph as part of their routine eye examination. While they are not part of a standard NHS sight test, both scans together cost £25.00, which represents good value for peace of mind. OCT scans and retinal photography are included in the cost of a private eye examination.
Seeing beneath the surface is essential to the health of your eyes
3D OCT screening diagnoses potentially serious conditions that can affect your eyesight and your overall well-being.
The Scientific Stuff!
Using a Topcon state-of-the-art 3D OCT camera, your optometrist will take both a digital photograph and a three dimensional cross sectional scan of the back of your eye in one sitting. This allows us to instantly diagnose a number of common conditions. The scan is non-invasive, painless, simple and quick.
What’s more, the software can automatically detect even the most subtle changes to the retina with every eye test you take. This gives you an invaluable ongoing record of the health and condition of your eyes.
What Can the Scan Check For?
Common conditions identified through regular OCT screening include:
1. Age-related Macular Degeneration
Macular degeneration causes the gradual breakdown of the macular (the central portion of the eye).
OCT cannot only identify this condition and its type (there are two types, wet and dry) but also monitor its progress, for example if you are undergoing treatment for such a condition. Unfortunately the risk of developing macular degeneration increases with age, and it is the most common cause of vision loss in individuals over the age of fifty.
Diabetic retinopathy is a major cause of visual impairment among adults. Here in the UK, more than two million people have been identified as having diabetes. OCT examination enables early detection, which greatly improves the success rate of treatment.
Glaucoma damages the optic nerve at the point where it leaves the eye. Recent statistics suggest that some form of glaucoma affects around two in every 100 people over the age of 40. The danger with chronic glaucoma is that there is no pain and your eyesight will seem to be unchanged, but your vision is being damaged. An OCT examination will confirm if you are at risk, or indeed what stage of glaucoma you may have.
4. Macular Holes
A macular hole is a small hole in the macular – the part of the retina which is responsible for our sharp, detailed, central vision. This is the vision we use when we are looking directly at things, when reading, sewing or using a computer. There are many causes of macular holes. One is caused by vitreous detachment, when the vitreous pulls away from the back of the eye and sometimes it does not ‘let go’ and eventually tears the retina, leaving a hole. Extreme exposure to sunlight (for example staring at the sun during an eclipse) can also cause a macular hole to develop.
5. Vitreous Detachments
Vitreomacular traction can clearly be diagnosed through OCT providing invaluable information about the current relationship between the vitreous and the retinal surface of the eye. As people get older the vitreous jelly that takes up the space in our eyeball can change. It becomes less firm and can move away from the back of the eye towards the centre, in some cases parts do not detach and cause ‘pulling’ of the retinal surface. The danger of a vitreous detachment is that there is no pain and your eyesight will seem unchanged but the back of your eye may be being damaged.