What Is an OCT Eye Scan?
Optical coherence tomography is a diagnostic (not surgical) test. It uses light waves, not X-rays or radiation, to capture very high-resolution images of the retina, the optic nerve and, in some cases, the drainage structures at the front of the eye. The result is a layered image, a little like a microscopic scan of the eye tissue, allowing structures only a few micrometres thick to be measured and compared over time.
Unlike a standard photograph of the back of the eye, an OCT scan shows what lies beneath the surface. This means subtle thinning of the nerve fibre layer, early fluid or swelling at the macula, or narrowing of the drainage angle can often be identified before they cause noticeable symptoms.
Who May Benefit From an OCT Eye Scan?
An OCT eye scan may be recommended where more detailed information about the structure of the eye would help guide diagnosis or treatment. It could be considered if you:
- Have been diagnosed with, or are suspected of having, glaucoma
- Have raised eye pressure (ocular hypertension) that needs monitoring
- Have a close family history of glaucoma and want a baseline assessment
- Have been referred by your optometrist after an unusual optic disc appearance or borderline scan result
- Notice blurred or distorted central vision, or gaps in your side vision
- Are being assessed for cataract surgery, where macular health can influence the choice of lens and the expected visual outcome
- Have narrow drainage angles or have previously had an episode of acute angle closure
Not everyone attending an eye clinic requires OCT imaging. Whether a scan is appropriate for you, and how often it should be repeated, depends on your diagnosis, your risk factors and your clinical examination. Ms Diana Urbaneja will advise based on your individual assessment.
Conditions and Problems the Scan Helps Assess
OCT imaging is used to support the assessment and long-term monitoring of a range of conditions, including:
- Glaucoma and glaucoma suspects: measuring the thickness of the retinal nerve fibre layer and the macular ganglion cell layer, which may thin as glaucoma progresses
- Ocular hypertension: establishing a baseline so that any future structural change can be detected
- Narrow angles and acute angle closure: assessing the anatomy of the drainage angle
- Macular conditions: identifying fluid, swelling, membranes or age-related changes at the centre of the retina
- Pre-operative cataract planning: confirming the health of the macula before surgery with a standard or premium intraocular lens
- Post-operative monitoring: checking the retina if vision does not improve as expected after surgery
Potential Benefits
Used appropriately, an OCT scan may:
- Help detect structural changes at an earlier stage than symptoms alone would suggest
- Support a more confident diagnosis where clinical findings are borderline
- Provide objective measurements that can be compared over months and years
- Help distinguish glaucoma from other causes of an unusual optic nerve appearance
- Inform decisions about whether to start, adjust or escalate treatment
- Support realistic discussion about likely outcomes before cataract or glaucoma surgery
The scan itself does not treat any condition. Its value lies in the quality of information it provides to guide evidence-based management, in line with national guidance on glaucoma care from NICE and standards set by the Royal College of Ophthalmologists.
Consultation and Assessment
OCT imaging is carried out as part of a full ophthalmic consultation. A typical appointment may include:
- A discussion of your symptoms, general health, medications and family history of eye disease
- Measurement of your vision and eye pressure
- Examination of the front and back of the eye at the slit lamp
- Visual field testing, where relevant
- OCT imaging of the optic nerve, macula or anterior segment as clinically indicated
- A clear explanation of the findings, the possible diagnosis and the options available, including the risks, benefits and alternatives of any treatment
You may be offered dilating eye drops to widen the pupil and improve image quality. These can blur your vision temporarily and make you sensitive to light for a few hours, so it is sensible to arrange transport rather than drive yourself home.
How the Scan Is Performed
The scan takes place in the outpatient clinic and requires no anaesthetic, no needles and no hospital stay. You will be asked to sit and rest your chin and forehead on a support, then look at a small target light while the scanner passes a beam of light across your eye. You may see flashing or moving patterns. Each eye usually takes only a minute or two, and you can blink normally between captures.
Images are reviewed by Ms Diana Urbaneja, often during the same visit, and stored so they can be compared with future scans. In many cases the results are discussed with you before you leave.
Aftercare and Follow-Up
There is no recovery period after an OCT eye scan itself and you can return to normal activities straight away, unless dilating drops have been used. Follow-up depends on the findings. Patients with stable ocular hypertension may be reviewed less often, while those with progressing glaucoma may need more frequent imaging and pressure checks.
Seek prompt medical attention if you develop sudden loss of vision, severe eye pain, redness with vomiting, or seeing haloes around lights, as these can indicate an urgent problem such as acute angle closure.
01
Scan
Quick, non-contact imaging
02
Review
Images discussed with your consultant
03
Next steps
Monitoring or treatment agreed
Guide Price
Price TBC
Often included as part of a consultation. See the pricing page for standalone scan costs.
At a glance
Duration
~10-15 min
Preparation
None
Results
Reviewed with your consultant
Next steps
Follow-up as needed