Liu H, et al. - An estimation was pursued of the area of optic nerve subarachnoid space (ONSASA) in patients with normal tension (NTG), primary open angle glaucoma (POAG) and controls. Researchers also attempted to discern its link with relevant ocular and systemic parameters. When compared to normal control, the ONSASA was found to be smaller in NTG. This was observed to be compatible with a lower cerebrospinal fluid pressure in the optic nerve in NTG. This data depicted that trans-lamina cribrosa pressure difference could be abnormally higher in NTG group than in normal control.

Methods

• The scheme of this research was a cross-sectional study.
• The eligible candidates consisted of 40 patients with NTG, 42 with POAG and 45 healthy controls.
• With the aid of a 12.5 MHz linear array probe, researchers carried out B-scan ultrasound, binocularly.
• Herein, the measurement of the optic nerve subarachnoid space (ONSAS) and calculation of the ONSASA were used ImageJ1.51e analysis software by two experienced observers in a masked manner.

Results

• Considerably smaller ONSASA was reported between 3 to 7mm behind the globe in NTG (5.15±0.81mm²) than that in the POAG (6.24±1.62mm², p=0.0008 or control (6.40±2.20mm²; p=0.0007) groups.
• No prominent variation was found in ONSASA in the POAG and control groups (p=0.13). ONSASA exhibited a notable link with mean IOP (p= 0.0004) and highest IOP (p=0.0007).
• It was determined that the ONSD in NTG compared to POAG appeared to be notably different at 3mm (4.46 ± 0.43mm vs 4.79 ± 0.40mm, p=0.0007), 5mm (4.40 ± 0.39mm vs 4.65 ± 0.47mm, p=0.003) and 7mm (4.3 ± 0.35mm vs 4.61 ± 0.30mm, p=0.004) behind the globe.