Effects of axial elongation on ganglion cell complex thickness and retinal capillary density in the peripheral retina among highly myopic eyes

Abstract Background/Objectives: To investigate the effects of axial elongation on ganglion cell complex (GCC) thickness and retinal capillary density (CD) in the circular region (12 mm diameter) using wide-field swept-source optical coherence tomography angiography. Subjects/Methods: This retrospective and cross-sectional study included 506 eyes. Fovea-centred 15 × 12 mm² scans were acquired to measure the subregional GCC thickness and CD in the whole retina, superficial capillary plexus (SCP) and deep capillary plexus (DCP) among three groups: normal controls, high myopia (HM) eyes with an axial length (AL) <28 mm, and HM eyes with an AL >28 mm. The magnitude of GCC thickness and retinal CD changes with axial elongation was estimated using multivariable linear regression models. Results: The GCC thickness and retinal CD in HM eyes with an AL >28 mm were lesser than those in the other two groups in most regions (P<0.05). In HM eyes with an AL <28 mm, GCC beyond the 3 × 3 mm² area was generally thinner than that in normal controls (P<0.05), while a significant reduction in CD occurred only in the 9–12 mm whole retina, 9–12mm superior SCP and 6–12 mm DCP (P<0.05). The GCC thickness and retinal CD with axial elongation demonstrated the greatest reduction in the subregions beyond 6 × 6 mm². Conclusions: GCC thickness beyond the 3 × 3 mm² area and peripheral retinal CD beyond the 6 × 6 mm² area were more susceptible to axial elongation, thereby deserving particular attention.