Retinal nerve fibre layer thickness profile in normal eyes using third-generation optical coherence tomography

Area of Science:

• Ophthalmology
• Medical Imaging
• Neuroscience

Background:

• Retinal nerve fibre layer (RNFL) thickness is a key indicator of optic nerve health.
• Accurate RNFL measurement is crucial for diagnosing and monitoring glaucoma and other optic neuropathies.
• Third-generation optical coherence tomography (OCT) offers high-resolution imaging of the RNFL.

Purpose of the Study:

• To establish normative radial profiles of RNFL thickness using third-generation OCT.
• To compare OCT-derived RNFL thickness measurements with previously reported histologic data.
• To assess the accuracy of OCT measurements, particularly near the optic disc margin.

Main Methods:

• Twenty normal eyes were scanned using a third-generation OCT device.
• Circular scans were performed at increasing distances (up to 1400 microm) from the optic disc margin.
• RNFL thickness was measured in four radial sections (superotemporal, superonasal, inferonasal, inferotemporal) and at the disc margin.

Main Results:

• A statistically significant interaction was found between quadrant location, distance from the disc margin, and RNFL thickness (P<0.001).
• RNFL thickness significantly decreased with increasing distance from the optic disc margin across all sections (P<0.001).
• OCT measurements were significantly thinner than histologic measurements in the area close to the optic disc margin (P<0.001).

Conclusions:

• Four distinct normal OCT RNFL thickness radial profiles were successfully established.
• OCT measurements of RNFL thickness near the optic disc margin are significantly thinner compared to histologic data.
• These findings highlight the importance of considering measurement location when interpreting OCT RNFL data.