A method of determining a diameter of a sheath of an optic nerve includes obtaining, by a processor, scan data representative of the optic nerve sheath, analyzing, by the processor, the scan data to find a position of a globe-optic nerve interface point, segmenting, by the processor, the scan data, processing, by the processor, the segmented scan data at an offset from the position of the globe-optic nerve interface point to determine boundary positions of the optic nerve sheath, and calculating, by the processor, the diameter of the optic nerve sheath based on the determined boundary positions.