Have you heard that your next eye assessment will involve “optical coherence tomography” (OCT), and you are wondering what it is, why it’s done, and whether you will be left with sore eyes for days after your vision check-up? Don’t worry - OCT scans are painless, non-invasive, and quick. At the same time, they can offer your optometrist precious information that they can use to detect many eye conditions much earlier (even before you notice any changes in your vision), so you can help safeguard your vision and get the best outcomes for your eye health in the long term. Here’s what you should know about OCT scans.

Optical Coherence Tomography: What Is It?

Simply put, OCT is a type of specialised scan that assists optometrists in assessing the health of your eyes by allowing them to see what your eye looks like beneath its surface. OCT scans go one step further than standard 2D retinal photographs, using light waves to create intricately detailed, high-resolution 3D images of all layers and structures within your eye by taking cross-section pictures.

The level of detailed imaging that OCT scans provide allows your eye care professionals to assess important aspects of your eyes, including your vitreous humour (the jelly-like substance that fills your eyeball), your retina (the light-sensitive layer at the back of your eye), the macula (an area at the centre of your retina responsible for central vision) and the optic nerve (a nerve that sends signals from your eye to the brain to produce the images we see) - and detect even subtle changes that can be indicative of early-stage diseases or other issues.

What Conditions Can OCT Scans Help Detect?

OCT scans can help to identify:

• Diabetic retinopathy
• Retinal detachment
• Age-related macular degeneration
• Macular holes
Glaucoma (up to four years earlier than traditional methods)
• Macular swelling or creases/bulges (known as macular ‘pucker’)
• Vitreous traction
• Blood vessel abnormalities, including blockages
• Changes to the optic nerve

Outside of the field of optometry, these scans have also been shown to be a useful diagnostic tool in diagnosing early-stage skin cancers, among other conditions and areas of the body, including imaging the vessels of the heart, other skin conditions, dental tissues, the gastrointestinal tract, and the nerves when evaluating the central nervous system.

The OCT Scan Process

The OCT scan process is straightforward, being completely non-invasive and painless. The scanning technology uses low-power infrared laser light and will measure the light that reflects off your retina and optic nerve without radiation or X-rays. The process takes just minutes, with the results appearing instantly in digital format. To complete the scan, you’ll typically:

• Place your chin on the chinrest
• Keep your eyes open while looking at a specified target (like a dot)
• During this time, the OCT machine scans your eye
• Your optometrist will have the digital files available to assess, review and discuss with you

In some cases, before the above process, your optometrist may recommend dilating your eyes to offer an even more extensive view of your retina. This may be offered if you have a history of eye disease or other factors. Dilation is done simply using eye drops that can blur your eyesight. Your sensitivity to light may temporarily increase, so you may reach for that pair of sunglasses following your appointment.

It’s important to note that as OCT relies on light waves, there are some situations where it may not be suitable due to producing inaccurate results, such as for conditions that interfere with light passing through the eye, e.g., dense cataracts. Your eye care professional will always screen for suitability before performing this scan.

When Should I Have An OCT Scan - Can I Book In For It Directly?

The OCT is a test that may incur an extra cost. At the time of having a full eye exam, the optometrist will discuss this. It is advisable to have this done, as it allows the complete and detailed record of the eye status saved for future comparison.
Of course, early detection and intervention is the goal of saving sight.

You can book your Optical Coherence Tomography scan as part of your regular eye test by contacting an Optical Co clinic near you.