Abstract
Subarachnoid space (SAS) around optic nerve can be visible with swept-source optical coherence tomography (SS-OCT). However, the relevant factors for its visibility and width have not been reported. In this prospective study, 193 eyes with high myopia were evaluated by SS-OCT. The relationship between age, gender, axial length, optic disc area, parapapillary atrophy (PPA) area, peripapillary choroidal thickness with the visibility and width of SAS were assessed. The results showed that SAS was observed in 125 (64.8%) and not observed in 68 (35.2%) eyes. Visibility of SAS is associated with long axial length, high myopia, thin choroid, large PPA and large optic disc areas. Among these associations, PPA area was the only independent factor (b = 0.177, p < 0.001). The width of SAS was associated with thin choroid, long axial length, large optic disc area and large PPA area. Multivariant analysis showed that optic disc area and PPA area were independent factors for the width of SAS (b = 30.8, p = 0.016 and 16.2, p < 0.001 respectively). These results suggested that SAS was extended into the peripapillary region possibly due to extension of posterior sclera in high myopia.
Highlights
subarachnoid space (SAS) was always observed temporal to the ON in eyes with large temporal conus. while SAS was observed on both sides of the optic nerve in eyes with annular atrophy
Orbital fat was visible as a grayish tissue area with many relative hyperreflective dots, adjacent to the SAS and optic nerve through the dura mater. (Fig. 1) The hyperreflective dots had a more uniform structure, which helped to differentiate it from the trabeculae structures within SAS
We found that visibility of SAS was independently associated with the area of parapapillary atrophy (PPA), and the width of SAS was independently associated with optic disc area and PPA area
Summary
The purpose of this study is to identify the ocular factors associated with the visibility and width of SAS from swept-source OCT in highly myopic eyes
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Published Version
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