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Optical Coherence Tomography (OCT)

Optical Coherence Tomography (OCT) using Cirrus 4000 HD-OCT

Optical Coherence Tomography uses very long wavelength light (similar to infra red light), along with a technique called interferometry in order to image individual structures and layers of the retina. Using OCT, a resolution as fine as four microns in diameter (four millionths of a meter) is achievable using high-definition OCT.

For this reason, OCT is perhaps the greatest advance in ophthalmic diagnostic technology in several decades.

Using high-definition OCT equipment in our clinic, our ophthalmologists are able to identify tiny abnormalities within retinal layers that would otherwise be impossible to see using traditional retinal imaging. OCT is also used to track the progress of diseases such as macular degeneration, diabetic retinopathy, glaucoma and other disorders of the macula and retina.

In the case of macular degeneration, for example, regular OCT imaging of the macula can catch wet AMD changes very early, allowing vision to be restored using treatment with drugs such as Lucentis or Avastin.
For those patients with glaucoma or who are at risk of developing glaucoma, OCT is used to detect subtle changes in the health of the retinal nerve fibre layer near the optic disc. These changes often precede vision loss due to glaucoma, so can allow treatment to be commenced before vision is impaired.


Using HD-OCT imaging, highly detailed images of the retina can be taken.  At left can be seen the macula, where there is a pronounced "dip" in the surface of the retina, at the fovea (the centre of the macula).

The optic disc can be seen to the right, where an even greater "pit" can be seen.  Here, retinal nerve fibre layers exit the retina to form the optic nerve.