Optical · 4 min read

What Does an OCT Scan Show That a Standard Eye Test Can't?

A standard eye exam is when your optometrist uses a number of tools, evaluating your vision and looking at the back of your eye. In some cases, they may take a digital retinal photograph, providing a 2D picture of your retinal surface, used to identify any abnormalities, yet it only tells a small portion of the story. In order to understand exactly what is happening with your ocular health, your optometrist needs to see below the surface, which is where Optical Coherence Tornography (OCT) scans come in.

24 May 2026 · EyeSmile Clinical Team · Whitton, Twickenham

macro detail of a human iris representing OCT retinal imaging

The 3D Difference – A Look Below the Surface

Imagine a standard retina photograph as a photo of a coconut, you can see if its cracked, but you don't know if it has coconut milk inside. An OCT scan works like an ultrasound, using light waves, creating a cross-section through the tissue, mapping the microscopic layers in 3D detail.

This advanced technology enables your optometrist to see and measure the thickness of each layer, providing them with a deep view where they can identify any serious eye conditions long before they start negatively impacting your vision.

What OCT Scans Can Detect Early

OCT scans peel back the layers of your eye, showing early detection of three major sight-threatening conditions, including:

  • Glaucoma – a condition that damages the optic nerve due to a build up of internal eye pressure. OCT scans measure microscopic thinning of the optic nerve fibre layers, enabling optometrists to catch the disease early, long before you experience symptoms
  • Age-Related Macular Degeneration – OCT scans identify microscopic pocks or fluid, along with subtle deposits that are growing between the deep retinal layers far before standard tests can identify AMD
  • Diabetic Retinopathy – OCT scans are invaluable to patients managing diabetes. The scan is effective in detecting minor fluid leaks and swelling deep inside the issues before any surface bleeding occurs.

Conclusion

Your eyes can appear healthy on the outside, but an OCT scan can provide any advanced warning that you may have an eye disease that requires early intervention. This is a comprehensive test that enables your optometrist to gain a clear view of your retina, breaking down the layers, catching any diseases early, while they are still treatable. Contact EyeSmile Optical today to book your OCT Scan without delay.

Written by the EyeSmile clinical team — dental and optical clinicians in Whitton, Twickenham. This article is for general information only and does not constitute clinical advice.

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FAQs

Frequently Asked Questions

Call EyeSmile Optical if you have any questions that are not answered here.

Is OCT scanning painful or uncomfortable?

OCT scans are non-invasive and not painful in any way. You look into a machine, focusing on a small target and the scan is completed within seconds. There is no contact and no dilating drops needed, in most cases.

How often should I have an OCT scan?

At EyeSmile, we recommend an annual OCT scan for most people. If your previous scan showed early changes, you may require more frequent monitoring. Your optometrist will advise you accordingly during your consultation.

Is OCT worth the extra cost?

Definitely. Standard eye exams cannot see below the retinal surface. If you are over forty or have any risk factors, we highly recommend an OCT scan to identify any problems early on, providing you with an effective treatment plan to preserve your vision.

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