What an OCT scan shows
Optical Coherence Tomography uses light waves to build a cross-sectional image of the retina — the equivalent of a very high-resolution slice through the tissue, produced without touching the eye.
The retina is only about a quarter of a millimetre thick, but it is made of distinct layers, and most retinal disease shows itself as a change in one of them. Looking at the retina through a lens shows its surface. OCT shows what is happening inside it: fluid collecting between layers, a hole that does not pass all the way through, a membrane wrinkling the surface, or a nerve fibre layer that has quietly thinned.
Our blog has a fuller explanation of what OCT is and why it matters.
What it is used for
Diabetic macular oedema. OCT measures retinal thickness numerically, so swelling can be detected before vision drops and tracked precisely between visits. See diabetic retinopathy treatment.
Age-related macular degeneration. It distinguishes dry from wet disease and shows fluid from abnormal vessels, which is what determines whether injections are needed.
Macular hole and epiretinal membrane. Both are diagnosed and staged on OCT, and the stage guides whether and when to operate.
Glaucoma. Retinal nerve fibre layer thinning can appear on OCT before it shows on a visual field test, which matters in a disease where loss is permanent. See glaucoma treatment.
Retinal detachment assessment. Whether the macula is still attached is the strongest predictor of visual outcome, and OCT settles that question.
Monitoring treatment. For patients on a course of injections, the scan at each visit is what decides the interval to the next one. The treatment schedule is driven by the scan, not by the calendar.
What happens during the scan
You sit at the machine and rest your chin and forehead on a support. You will be asked to look at a small target and hold still. The scan itself takes a few seconds per eye.
Dilating drops are often used first for a clearer image. They sting briefly, then blur near vision and increase light sensitivity for a few hours — bring sunglasses, and do not plan to drive yourself afterwards.
Nothing touches the eye, nothing is injected, and there is no radiation.
Why having it in-house matters
Retinal decisions usually depend on the scan. If the scan has to be done elsewhere, the patient makes two journeys and the decision waits for the second one — and in conditions like macula-threatening detachment or acute macular oedema, that delay has a cost.
Having OCT at the centre means the scan, the interpretation and the treatment decision happen in the same visit. For a patient travelling in from Tanur, Kottakkal or Valanchery, that is often the practical difference between getting treated and getting scheduled.