Association between morphological characteristics of the optic disc and other anatomical features of the fundus in highly myopic eyes

Purpose: To investigate associated factors with optic disc characteristics in high myopia patients. Methods: According to the meta-analysis of pathologic myopia study, patients were divided into groups from categories 1 (C1) to C4. The diameters, tilt ratio, and rotation degree of optic disc, and the diameters of parapapillary atrophy were measured among other morphometric variables. Results: Totally 147 eyes (84 patients) were included. Longer horizontal optic disc diameter was associated with smaller tilt ratio ( p < 0.001, unstandardized regression coefficient B: −0.59), greater rotation degree ( p < 0.001, B: 0.01), and longer horizontal delta zone diameter ( p < 0.001, B: 0.09). Longer vertical optic disc diameter was associated with smaller rotation degree ( p < 0.001, B: 0.01), longer vertical delta zone diameter ( p < 0.001, B: 0.16), and longer disc–fovea distance (DFD; p < 0.024, B: 0.14). Generally, the horizontal optic disc diameter of C3 and C4 groups was smaller than C1 and C2, while vertical diameter and tilt ratio was greater than in C1 and C2. After setting axial length (AL) as an independent variable, horizontal diameters and tilt ratio still showed significant differences, while vertical diameters did not show significant differences. Conclusion: Axial elongation was associated with an increase of vertical optic disc diameter that was correlated with an reduction of optic disc rotation degree. By contrast, horizontal optic disc diameter elongation was correlated with an reduction of optic disc tilt ratio and an increase of optic disc rotation degree, which was independent of axial elongation.