Abstract
Purpose :
To study the morphologic patterns of optic nerve head (ONH) deformation in eyes with myopic open angle glaucoma (OAG) and associated clinical implications.
Methods :
We imaged the deep ONH structure with radially performed enhanced-depth optical coherence tomography (OCT) in patients with myopic OAG. By the ovality index, externally oblique border tissue (EOBT), and nasal deviation of central retinal vascular trunk (N-CRVT), we grouped the myopic ONH deformation into six patterns. We measured the areas of Bruch’s membrane opening (BMO), choroidal border tissue (CBT)-BMO, and exposed scleral flange (ESF)-BMO areas and the lengths of CBT and ESF in maximum EOBT by manual delineation of the landmark.
Results :
We had 105 eyes of 67 patients with the average refractive error of -6.75 ±2.75 D and axial length of 26.5 ± 1.10 mm. Eyes were grouped into patterns 1 (round disc/EOBT[-]/N-CRVT[-], 9 eyes), 2 (oval disc/EOBT[+]/N-CRVT[-], 4), 3 (round disc/EOBT[+]/N-CRVT[+], 14 eyes), 4 (oval disc/EOBT[+]/N-CRVT[+], 57 eyes), 5 (oval disc with flatter nasal curvature/EOBT[+]/N-CRVT[+], 7 eyes), and 6 (slit-like disc/EOBT[+]/N-CRVT[+], 14 eyes). The BMO area, CBT-BMO area, ESF-BMO area, CBT/ESF ratio, CBT and ESF lengths, and BMO distance were distributed significantly differently among the 6 patterns. The CBT length gradually increased from pattern 1 to 6 (114.3 ± 67.6, 288.5 ± 79.3, 426.2 ± 136.9, 460.7 ± 194.3, 652.0 ± 155.4, and 766.8 ± 234.8 um, respectively, P < 0.001). Patterns 5 and 6 had significantly lower CBT-BMO/BMO area and ESF-BMO/BMO area ratios. Pattern 6 had significantly lower CBT-BMO area and ESF-BMO area than other patterns. Interestingly, isolated PMB defect was significantly more frequently observed in patterns 5 and 6 than in other patterns (P < 0.001).
Conclusions :
The morphology of myopic ONH deformation exhibited diverse patterns, unlike the commonly expected combination of increased ovality index, elongated EOBT, and nasal deviation of CRVT. The clinical significance of these structural variations in deep ONH morphology may be associated with the regional vulnerability of axons, such as the PMB, in glaucoma.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.