Relationship between lamina cribrosa curvature and the microvasculature in treatment-naive eyes

Background/Aims To investigate the relationship between the lamina cribrosa (LC) curvature and the microvasculature within the LC in treatment-naive eyes with normal-tension glaucoma (NTG) and in healthy eyes. Methods Forty-one eyes with treatment-naive NTG and 41 age and sex-matched healthy control eyes were included. The optic nerve head (ONH) area was scanned using spectral-domain optical coherence tomography (OCT) to examine the LC curvature quantified as the LC curvature index (LCCI). OCT angiography of the ONH area was performed to determine the LC vessel density (LCVD) in the en face images obtained from the layer segmented at the level of the LC. The LCVD was calculated as the percentage area occupied by vessels within the measured region. Results The LCCI was larger (9.53 +/- 1.33 vs 6.55 +/- 1.02, p<0.001) and LCVD was smaller (28.0%+/- 6.1% vs 35.2 +/- 6.3%, p<0.001) in NTG eyes than in healthy eyes. There were overall significant associations of a smaller retinal nerve fibre layer (RNFL) thickness (p<0.001), a smaller visual field mean deviation (MD) (p=0.003) and a larger LCCI (p <= 0.004) with a smaller LCVD. In NTG group, the LCVD was positively associated with the RNFL thickness (p=0.012) and visual field MD (p=0.023), and negatively associated with the axial length (p <= 0.013) and LCCI (p <= 0.007). In healthy group, a smaller RNFL thickness (p=0.023) was associated with a smaller LCVD. Conclusion A larger LCCI was significantly associated with a smaller LCVD in treatment-naive NTG eyes but not in healthy eyes, indicating that mechanical strain potentially influences the perfusion within the LC in eyes with NTG.