OCT RNFL (Retinal Nerve Fiber Layer)

Looking at Your Optic Nerve in Extraordinary Detail

The optic nerve is the cable that carries all visual information from your eye to your brain. When this nerve is damaged — as happens in glaucoma — vision is lost permanently. OCT RNFL scanning allows us to measure the thickness of the nerve fibre layer surrounding the optic nerve with remarkable precision, detecting damage that is completely invisible in any standard eye examination.

What Is OCT RNFL?

OCT stands for Optical Coherence Tomography. It is an advanced imaging technology that uses light waves — not radiation — to produce highly detailed cross-sectional images of the layers of the retina. The RNFL scan specifically focuses on the Retinal Nerve Fiber Layer — the thin layer of nerve fibres that surrounds the optic nerve head. By measuring the thickness of this layer at multiple points around the optic nerve, we can detect thinning that indicates damage, often years before any visual field loss becomes apparent.

Why Is This Scan So Valuable?

• It detects glaucoma damage earlier than any other test currently available
• Nerve fibre thinning can be detected before visual field tests show any loss
• It provides an objective measurement that can be tracked and compared over time
• It helps distinguish between true glaucoma damage and normal variation
• It guides treatment decisions — showing whether current treatment is working

What Happens During the Scan?

Step 1 — Pupil Dilation (Sometimes)

Dilating eye drops may be used to widen your pupils for a clearer scan, though many modern OCT machines can perform the scan without dilation.

Step 2 — Sitting at the Machine

You rest your chin on the support and look at a target inside the machine. You simply need to keep your eye as still as possible — the scan itself is completely automatic.

Step 3 — The Scan

A beam of light scans across the retina around the optic nerve head. The machine takes hundreds of measurements in seconds, building a detailed thickness map of the nerve fibre layer.

Step 4 — Instant Results

A colour-coded map appears immediately, showing which areas of the nerve fibre layer are within normal range and which show thinning. Your specialist reviews this map alongside your clinical history and other test results.

Is the Scan Safe and Comfortable?

Completely. OCT uses light — not radiation — and is entirely non-invasive. The scan takes only a few minutes per eye, is painless, and produces no aftereffects. It can be repeated as often as needed to monitor your condition over time.

Why Patients Trust RGC Eye Hospital

• Advanced OCT technology for the highest resolution nerve fibre layer imaging
• Specialist glaucoma experts who interpret results with clinical depth and experience
• Results tracked over time to detect the earliest signs of progression
• A clear and honest discussion of what your scan shows and what it means for your care