Axial Length–Dependent Macular Choroidal Topography in POAG: A Wide-Field Swept-Source Optical Coherence Tomography Study

Purpose: To characterize the topography of the macular choroidal thickness (mCT) in POAG across axial lengths (AXLs), and to determine the clinical factors associated with the mCT. Methods: Wide-field swept-source optical coherence tomography with a 30 × 30 macular grid (6 mm × 6 mm) was used to generate spatial maps of the mCT and macular ganglion cell-inner plexiform layer thickness (mGCIPLT). The mCT was compared pointwise between POAG and control eyes, and cluster-based permutation testing was used to assess topographic significance in the entire cohort and in three subgroups stratified by AXL (<24.5 mm, 24.5-26.0 mm, and ≥26.0 mm). Clinical factors associated with the mCT were evaluated using regression analyses. Results: This study included 117 POAG eyes and 157 control eyes. While the mCT was only marginally thinner in POAG eyes than in controls, topographic analyses of the mCT revealed areas of localized thinning in the papillomacular and inferotemporal peripapillary areas in POAG, which did not overlap with the pattern of mGCIPLT reduction. These topographic changes were observed only in eyes with an AXL of <26.0 mm, with no regional differences in eyes with an AXL of ≥26.0 mm. Conclusions: In POAG eyes, the mCT reduction was localized to the papillomacular and inferotemporal peripapillary regions, which are critical areas for central visual function and topographically distinct from structural retinal ganglion cell loss. This pattern was not observed in eyes with long AXLs, presumably because significant axial-elongation-induced thinning restricts further discernible changes. Future studies are needed to determine the clinical significance of mCT alterations in POAG.