Published 06 May 2024
Optical Coherence Tomography (OCT) scans are available across all GMHBA Eye Care locations and may be part of your next eye examination. Find out more about this important piece of equipment and what you can expect below.
What is an Optical Coherence Tomography (OCT) scan?
Optical Coherence Tomography (OCT) is modern technology that allows us to see the retina in 3D using light waves. It provides cross sectional images of important structures like the optic nerve, macula and cornea. It is non-invasive and scans can be captured in a matter of minutes, without the use of dilating drops in most cases. OCT can sometimes detect problems prior to any symptoms being reported, which allows for preventative care and early intervention, improving vision and allowing best prognosis.
How does an OCT work?
An OCT scan has some similarities with an ultrasound in that it provides real-time internal imaging. However, it uses harmless light waves, instead of sound waves, to illuminate and scan your retina, the light-sensitive part of the eye. This allows your optometrist to examine your retina in an extremely detailed way.
Above: Detailed imagery of the eye from an Optical Coherence Tomography scan.
What happens during an OCT scan?
Like other tests you may do during your eye examination, you will place your forehead and chin on a rest in front of the machine. Your optometrist will then guide you through the scans and a fixation light is used to ensure you are looking in the correct direction for each scan. The scan usually takes around 5–10 minutes.
An OCT can be done with or without dilating eye drops. Dilating drops may be used to widen the pupil and help capture detailed images. Most patients find dilating drops to be painless; however, some light sensitivity and blurred vision can be expected for a few hours afterwards.
What does an OCT measure?
The retinal tissue has 10 distinct layers, and OCT scans capture each layer in remarkable detail. An OCT can capture detail at 8-10um resolution, which is similar to the thickness of a strand of hair! By measuring these layers so precisely, an OCT helps monitor eye health over time and can detect early signs of conditions like macular degeneration, diabetic eye disease, and glaucoma.
Do I need an OCT?
An initial OCT scan is recommended for all new patients to GMHBA Eye Care. This acts as a baseline to assist with monitoring for any future retinal changes.
For people under 65 years of age, a routine OCT scan is often recommended every 2-3 years. For people over 65 years of age, this may be annually. In some cases, patients with specific risk factors may require more frequent OCT scans.
- Some patient risk factors may include:
- Family history of eye conditions (glaucoma, macular degeneration, diabetic retinopathy)
- Medical history (i.e. blood pressure, cholesterol, diabetes, heart conditions, medications)
- Smoking
- Changes in vision or new visual symptoms
- Low/reduced vision
All of our optometrists are on hand to help if you have any questions regarding this piece of equipment.
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About the author
Alice Bongers is an optometrist at GMHBA Eye Care. Alice completed her Bachelor of Vision Science /Master of Optometry at Deakin University in 2016 and has been with GMHBA since 2018. Alice has a broad interest in all aspects of optometry.
