Optical coherence tomography is a non-contact scan that uses reflected near-infrared light to build cross-sectional images of the retina and optic nerve, with detail down to a few thousandths of a millimetre. It is sometimes compared to an ultrasound made with light. A scan takes seconds and nothing touches the eye.
It has changed the management of macular disease and glaucoma, because it reveals fluid, swelling and nerve fibre thinning well before they can be seen by looking into the eye. It images structure, not function, so it is interpreted alongside vision tests, visual fields and the clinical examination.
What OCT Eye Scan (Optical Coherence Tomography) shows
At the macula, OCT displays each retinal layer and picks up fluid within or beneath the retina, as in wet age-related macular degeneration, diabetic macular oedema and retinal vein occlusion. It shows macular holes, epiretinal membranes, vitreomacular traction and central serous retinopathy. Around the optic nerve it measures the retinal nerve fibre layer and ganglion cell layer and compares them with age-matched norms, which helps to detect and track glaucoma. OCT angiography (OCT-A) maps blood flow in retinal and choroidal vessels without dye. Anterior segment OCT images the cornea and drainage angle, used for keratoconus, corneal grafts and narrow angles.
When OCT Eye Scan (Optical Coherence Tomography) is recommended
- Blurred or distorted central vision, or a new dark patch
- Diabetes, as part of retinal screening when macular swelling is suspected
- Monitoring of wet macular degeneration and guiding injection intervals
- Suspected or established glaucoma, and raised eye pressure
- Before cataract surgery, particularly when premium lens implants are planned, to make sure the macula is healthy
- Long-term hydroxychloroquine use, and unexplained visual loss
Limits and situations where another test is better:
- Dense cataract, corneal scarring or vitreous haemorrhage can block the light and degrade the image
- It covers the central retina; tears or detachment in the far periphery need a dilated examination or widefield imaging
- Fluorescein angiography may still be required to find leaking vessels
- Very highly short-sighted eyes can give misleading nerve fibre readings when compared with the normal database
How to prepare
- No fasting or special preparation
- Bring glasses, a list of eye drops, and any earlier scans for comparison
- Dilating drops may be used, so bring sunglasses and avoid driving for 4 to 6 hours afterwards
- Remove contact lenses if asked
What happens during the test
You sit with your chin on a rest and look at a small target inside the machine. Each eye is scanned for 5 to 30 seconds while you try not to blink. There is no flash, puff or contact. With both eyes and several scan types, the test takes 5 to 10 minutes, a little longer if the pupils need dilating first.
Results and next steps
Images appear at once and the ophthalmologist usually reviews them with you in the same visit. Results may lead to reassurance, a follow-up interval, eye injections, laser, or referral for surgery. Ask for the scans in digital form, since future comparison on the same type of machine is what makes OCT most useful.
- Test time: 5 to 10 minutes
- Results ready: Immediately
- Back to everyday activity: None, or a few hours of blur with dilating drops
Safety and risks
- None from the scan itself; it uses harmless light and no radiation
- Temporary blurring and glare if dilating drops are used
- Very rarely, dilating drops can trigger an angle-closure attack in predisposed eyes
- Artefacts or borderline readings that prompt extra tests
Arranging OCT Eye Scan (Optical Coherence Tomography) in Türkiye
OCT is widely available and not a reason to travel. It is a standard part of the assessment before cataract, lens, retinal or laser vision surgery in Istanbul and of any retinal or glaucoma second opinion. Bringing previous scans lets the doctor judge change over time.
Send your previous reports and the question you want answered and a Clinic-Y coordinator replies within 24 hours with suitable teams and written, all-inclusive proposals side by side. Reviewing your case is free.
الأسئلة المتكررة
Is OCT the same as an optician's retinal photo?
No. A photograph shows the surface. OCT shows the layers in cross-section and measures their thickness.
Does it involve dye or injections?
No. Standard OCT and OCT angiography use light only. Fluorescein angiography is the test that uses dye.
How often is it repeated?
During injection treatment for macular disease, often at every visit. For glaucoma monitoring, typically once or twice a year.