Purpose: To evaluate the use of 3-dimensional ultrasound C-scan imaging for optic nerve diameter measurements.
Design: Prospective observational case series.
Participants: Thirty-eight normal eyes of 32 healthy adults.
Methods: Coronal C-scans of 38 normal optic nerves were imaged 3 mm behind the globe.
Main outcome measures: Optic nerve sheath diameter (ONSD) and optic nerve diameter (OND).
Results: Mean ONSD was 4.8 mm (range: 3.9-5.9; SD 0.6), whereas mean optic OND was 1.9 mm (range: 1.8-2.1; SD 0.1). Mean ONSDs were 4.9 mm (male), 4.5 mm (female), 5.0 mm (subjects younger than 50 years), and 4.6 mm (subjects 50 and older).
Conclusion: Coronal C-scans generated from 3-dimensional ultrasound can be used to measure the optic nerve diameters in adult eyes.