What Is an OCT Eye Scan and What Can It Show?
An OCT eye scan gives your optometrist a detailed view of structures at the back of your eye that cannot be assessed by vision testing alone. The scan is quick, non-invasive, and often completed as part of a comprehensive eye exam. It can help establish a baseline, identify subtle changes, and monitor certain eye conditions over time.
What does OCT mean
OCT stands for optical coherence tomography. The technology uses light waves to create high-resolution cross-sectional images of the retina, the light-sensitive tissue lining the back of the eye. It works a little like an ultrasound, but it uses light instead of sound.
A retinal photograph captures a broad, two-dimensional view of the retina. An OCT scan adds another perspective by showing the retina in thin layers. These tests are complementary, and your optometrist may use one or both depending on your age, eye health, symptoms, and clinical findings.
What can an OCT eye scan show
An OCT scan can help your optometrist assess the macula, optic nerve, and retinal layers. It may support the detection or monitoring of changes associated with conditions such as glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal swelling. It may also help document changes related to the vitreous, the gel that fills the eye.
OCT does not diagnose every eye condition on its own. Your optometrist interprets the images together with your symptoms, health history, visual acuity, eye pressure, retinal examination, and other test results.
What happens during an OCT scan
You sit in front of the OCT instrument, rest your chin and forehead against the supports, and look at a target. The device captures the scan without touching your eye. The imaging itself usually takes only a few moments per eye.
Your pupils may need to be dilated if your optometrist requires a wider view or if the images are difficult to obtain. Dilating drops can cause temporary light sensitivity and blurred near vision. Your clinic will let you know what to expect.
Why baseline imaging matters
A single OCT scan provides useful information, but comparison over time can be especially valuable. A baseline gives your optometrist a reference point for future exams. Small changes may become easier to recognize when current images can be compared with earlier scans taken on the same or a similar instrument.
Who may benefit from OCT imaging
Your optometrist may recommend OCT based on your examination rather than age alone. It can be particularly useful for people with diabetes, a family or personal history of glaucoma or retinal disease, high myopia, unexplained vision changes, or findings that need closer evaluation. It may also be used to monitor a known condition or treatment.
Does a normal OCT mean my eyes are healthy
A normal OCT result is reassuring for the structures captured, but it does not replace a complete eye examination. Some problems affect the front of the eye, peripheral retina, eye movements, focusing system, or visual pathways in ways that an OCT scan may not show.
Book a comprehensive eye exam
Asgarpour Optometry provides comprehensive eye exams with OCT and retinal imaging at our clinics in Vancouver, Calgary, Edmonton, Ottawa, and Mississauga. Your optometrist will explain which tests are appropriate for you and review the findings in plain language.
Frequently asked questions
Is an OCT eye scan painful?
No. The scan is non-contact and uses light to capture images. You may see a bright target or brief flashes from the instrument.
Does OCT use radiation?
No. OCT uses light waves, not X-rays or ionizing radiation.
How often do I need an OCT scan?
There is no single schedule for everyone. Your optometrist will recommend imaging based on your risk factors, symptoms, examination findings, and whether a condition needs monitoring. However a yearly eye exam with a an OCT is a great way to prevent eye disease.
