Analysis of Peripapillary Geometric Characters in High Myopia Using Swept-Source Optical Coherence Tomography

PURPOSE. We measured the three-dimensional geometric profile around the optic nerve head (ONH) using swept-source optical coherence tomography (SS-OCT) in highly myopic eyes. METHODS. We studied 114 highly myopic eyes (<-6.0 diopters [D]) of 114 patients without glaucoma. Eyes were examined using the prototype SS-OCT. The retinal pigment epithelium (RPE) and chorioscleral interface were traced, and the mean y-axis coordinates of 24 sectors were calculated in circular peripapillary (3.4-mm diameter) images. The peripapillary tilting index (PTI) was calculated by subtracting the mean y-axis coordinate of the RPE in a sector from the mean of all sectors. The main outcome measures were the PTI and its association with the staphyloma depth from the OCT images and the ovality index (OI) of the ONH and peripapillary atrophy (PPA) area from fundus photographs. RESULTS. The PTI differed significantly (P < 0.0001) among the 24 sectors and was lowest at the inferotemporal sector (-1930.76 mu m). The minimal PTI value was in the temporal to inferotemporal sectors in 88 (77.2%) eyes and was correlated significantly with the OI (P < 0.0001) and age (P < 0.001) but not with the equivalent refractive error or axial length. The minimal PTI was correlated significantly with the PPA area (P < 0.05), minimal choroidal thickness (P < 0.05), macular choroidal thickness (P < 0.0001), and staphyloma depth (P < 0.0001). CONCLUSIONS. The peripapillary area is tilted inferotemporally in 77.2% of myopic eyes. Peripapillary tilting was markedly greater in older patients. Greater tilt was associated with a thinner choroid, more extensive PPA, and deeper staphyloma.