OCT Scan Explained: What This Eye Test Reveals
A board-certified ophthalmologist explains OCT imaging for patients in Yeongdeungpo, Guro, Gasan & Gwanak
Q. What is an OCT scan and what does it show?
An OCT (Optical Coherence Tomography) scan is a painless, non-invasive imaging test that produces detailed cross-sectional images of the retina and optic nerve, allowing an ophthalmologist to detect glaucoma, macular degeneration, diabetic retinopathy, and other conditions often before symptoms appear. At Nunehim Eye Center in Yeongdeungpo-gu, Seoul, an OCT scan is a routine part of comprehensive eye exams.
Q. How does an OCT scan work?
OCT uses low-energy, near-infrared light waves to scan the retina layer by layer, similar in concept to ultrasound but using light instead of sound. The test takes under a minute per eye, involves no needles, and usually requires only that you rest your chin on a support and look at a target light while the machine captures images.
Q. What can an OCT scan detect?
- Glaucoma, through measurement of optic nerve fiber layer thickness
- Age-related macular degeneration (AMD)
- Diabetic retinopathy and diabetic macular edema
- Epiretinal membrane and macular hole
- Early signs of retinal detachment risk
- Optic neuritis and other optic nerve conditions
OCT Screening: The Local Context
- ▸ Korea’s rapidly aging population means OCT-detectable conditions like glaucoma and AMD are becoming more common
- ▸ Diabetic retinopathy is a leading cause of vision loss among working-age adults, and OCT enables early detection
- ▸ Glaucoma often has no early symptoms — OCT can reveal optic nerve changes years before noticeable vision loss
- ▸ Working professionals in Yeongdeungpo, Guro, and Gasan increasingly request OCT screening due to prolonged screen time and Korea’s high rate of myopia
Q. Who should get an OCT scan?
OCT is recommended for anyone over 40, those with a family history of glaucoma, people with diabetes, patients with high myopia, and anyone noticing blurred or distorted vision — a profile common among patients we see from Gwanak and Dongjak.
We also recommend routine OCT screening even without symptoms for early detection, especially for patients in Gasan and Gwanak managing diabetes or hypertension, since both conditions can affect the retina silently.
Q. Is an OCT scan painful or does it require special preparation?
No — OCT is completely painless and non-contact, with no needles involved. You may see a brief flash of light during the scan. Pupil-dilating drops are sometimes used for a clearer view of the peripheral retina but are not always necessary, and results are typically reviewed with you the same day.
Q. How is an OCT scan different from a fundus photo?
A fundus photo captures a flat, two-dimensional picture of the retina’s surface, while OCT creates cross-sectional, layer-by-layer images — similar to a CT scan for the eye. This allows your ophthalmologist to measure retinal thickness and detect subtle structural changes that a surface photo alone cannot show.
Q. What symptoms mean you should get an OCT scan soon?
- Sudden blurred or distorted central vision
- Straight lines appearing wavy or bent (a possible sign of AMD)
- New floaters or flashes of light
- Gradual loss of peripheral vision
- Difficulty seeing in low light or at night
If you notice any of these symptoms, schedule an eye exam with OCT imaging promptly.
What OCT Detects
- Glaucoma
- Macular degeneration
- Diabetic retinopathy
Who Needs It
- Adults over 40
- Diabetics
- High myopia or family history of glaucoma
What to Expect
- No pain, no needles
- Under 1 minute per eye
- Same-day results review
A Note From Dr. Daniel Baik
“OCT has changed how we catch glaucoma and retinal disease early. As a board-certified ophthalmologist seeing patients from Yeongdeungpo and Guro, I recommend it as part of a routine eye exam for anyone over 40 or with risk factors like diabetes or high myopia — catching changes early makes a real difference in preserving vision.”
❓ Frequently Asked Questions
Q. How long does an OCT scan take?
The scan itself takes less than a minute per eye, and the full appointment including image review typically takes about 15–20 minutes.
Q. Does an OCT scan require eye drops to dilate my pupils?
Not always. Many OCT scans can be performed without dilation, though your ophthalmologist may recommend dilating drops for a clearer view of the peripheral retina in certain cases.
Q. How often should I get an OCT scan?
For most healthy adults, an OCT scan every 1–2 years as part of a comprehensive eye exam is reasonable, while patients with glaucoma, diabetes, or macular degeneration may need scans every 3–6 months to monitor progression.
Q. Can OCT detect glaucoma before I notice any vision loss?
Yes — this is one of OCT’s greatest strengths. It can reveal thinning of the optic nerve fiber layer years before a patient notices any peripheral vision loss, allowing earlier treatment.
Q. Is OCT covered by national health insurance in Korea?
Coverage depends on the clinical indication and diagnosis; OCT performed to monitor a diagnosed condition such as glaucoma or diabetic retinopathy is often covered, while purely screening exams may have different coverage. Our staff at Nunehim Eye Center can help clarify coverage for your situation.
Q. What’s the difference between OCT and a regular eye exam?
A regular eye exam checks visual acuity and overall eye health, while OCT provides detailed cross-sectional imaging of the retina and optic nerve, revealing microscopic changes invisible to the naked eye or a standard exam.
Q. Where can I get an OCT scan near Yeongdeungpo?
Nunehim Eye Center in Yeongdeungpo-gu offers OCT imaging as part of comprehensive eye exams, serving patients from Yeongdeungpo, Guro, Gasan, and Gwanak with same-day results review.
Book a Consultation
Nunehim Eye Center · nunehim.com · Yeongdeungpo-gu, Seoul
📍 Visit Nunehim Eye Center — Guro, Seoul
Convenient access from Guro, Gasan, Gwanak & Dongjak. Near Guro Digital Complex Station (Line 2).
Address: 551 Siheung-daero, Guro-gu, Seoul / nunehim.com
Hours: Mon–Fri 09:00–18:30 (lunch 13–14), Sat 09:00–14:00
Languages: Korean & English
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