Detailed cross-sectional images of the retinal layers and optic nerve head obtained using low-energy light; a standard examination for the diagnosis and follow-up of macular and glaucoma diseases.
Indication
- Diagnosis and treatment follow-up of age-related macular degeneration (dry/wet type)
- Evaluation of diabetic macular edema and diabetic retinopathy
- Monitoring the optic nerve head and retinal nerve fiber layer in glaucoma
- Diagnosis of macular hole, epiretinal membrane, and vitreoretinal interface disorders
- Follow-up of central serous chorioretinopathy and other macular fluid accumulations
- Objective evaluation of response to treatments such as anti-VEGF injections
- Assessment of retinal structure in high myopia, uveitis, and after trauma
Preparation
- Most devices can capture images without pupillary dilation; drops may be requested in some cases
- If you wear contact lenses, you may be asked to remove them; contrast improves
- If drops are administered, blurred vision may persist for several hours; a companion is recommended
- If you have prior OCT images, bring them along for comparison
- Fasting is not required; you may continue your medications as usual
How it's performed
- You will be asked to sit in front of the device and rest your chin on the chin rest with your forehead against the band
- You will be asked to fixate on the light point shown by the device; blinking is normal
- Low-energy infrared light is sent into the eye, and cross-sectional images are formed from the reflected signals
- The procedure is non-contact, painless, and does not involve radiation; recordings of a few seconds are taken for each eye
- Total acquisition time is generally 5-10 minutes; both eyes are imaged in the same session if needed
- Images are evaluated on the computer; results are usually interpreted by your physician on the same day
Post-procedure
- If no drops were used, you may resume your daily activities immediately
- Images are used directly for diagnosis or for follow-up by comparison with previous tests
- A treatment plan (e.g., anti-VEGF injection, laser, observation) is determined according to the findings
- In chronic conditions (macular degeneration, diabetic macular edema, glaucoma), repeat OCT is recommended at regular intervals
- It is important to consult promptly without waiting for the scheduled visit if new vision loss, visual field shadows, or distorted vision occur
Risks
- OCT is considered safe for the eye because it uses non-contact, low-energy light
- If drops are used, blurred vision and light sensitivity may last 4-6 hours
- Image quality may decline with eyelid tremor, dry eye, or dense cataract; repeat imaging may be needed
- In a small number of patients, prolonged steady fixation may cause mild dizziness or fatigue
FAQ
Is OCT painful, and does it involve radiation?
No. OCT is a non-contact imaging method; the eye is not touched and no pain is felt. It uses low-energy infrared light and does not involve ionizing radiation like X-ray or CT.
Are dilating drops required for OCT?
Most modern devices can produce clear images without drops. Pupil-dilating drops may be used in cases of corneal or lens opacity or when special imaging protocols are required; in this case, several hours of blurred vision is normal.
Shouldn't an MRI be done instead of OCT?
OCT and MRI serve different purposes. OCT provides micron-level cross-sectional images of the retina and optic nerve head, while MRI is preferred when posterior eye structures, optic pathways, and the brain need to be evaluated. The choice is made by the physician based on findings.
Can I have an OCT during pregnancy?
Yes. OCT is considered safe during pregnancy because it does not involve ionizing radiation or intravenous contrast agents. If drops are required, your physician will weigh the benefit-risk balance.
Related Information
Related Medical Services
Other services in the same specialty or with similar indications you may want to explore.
Fundoscopy
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Fundoscopy (dilated fundus examination) — direct examination of the retina, optic nerve, and ocular blood vessels.
Intravitreal injection
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Intravitreal injection — retinal therapy delivering anti-VEGF medications inside the eye.
Glaucoma follow-up
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Glaucoma follow-up — preserving vision through medication, visual-field testing, and optic-nerve monitoring.
Fundus Fluorescein Angiography
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Fundus fluorescein angiography (FFA) — a diagnostic test in which the retinal vessels are imaged using fluorescein dye.
Cataract Surgery
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Cataract surgery (phacoemulsification) — treatment of vision loss by replacing the clouded lens of the eye.
Visual field test
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Visual field test (perimetry) — map-based assessment of central and peripheral vision.
Intraocular Pressure Measurement (Tonometry)
Ophthalmology
Intraocular pressure measurement (tonometry) — determining eye pressure for glaucoma screening and follow-up.
Diabetic Retinopathy Laser Treatment
Ophthalmology
Diabetic retinopathy laser treatment — reducing the risk of vision loss in proliferative stage with panretinal photocoagulation.