Table 2.

Correlation between the optic nerve sheath, eyeball, and optic canal anterior (orbital) opening measurements (in mm)

Correlation between	Right eye	Left eye
	r	r
Distal ONSD*/ETD	0.74	0.69
Middle ONSD**/ETD	0.79	0.77
Proximal ONS area***/OC lumen area	0.82	0.84
ONS area at lumen/OC area at the lumen	0.96	0.95

*3 mm behind the globe.

**10 mm behind the globe.

***3 mm before entering the anterior lumen of the optic canal.

ETD – eyeball transverse diameter.

OC – optic canal.