Cortical thickness and volume alterations in patients with high myopia: a magnetic resonance imaging study

Background: The retina and optic nerve are integral components of the visual system and maintain direct anatomical and functional connections with the brain. Both structures are markedly affected in high myopia (HM). Accordingly, characterizing brain structural alterations associated with HM may provide important insights into its underlying neurobiological mechanisms. Using brain magnetic resonance imaging (MRI), this study aimed to evaluate regional gray matter (GM) and white matter (WM) volume changes, their relative percentages, and cortical thickness alterations in individuals with HM. Methods: High-resolution structural MRI, together with visual acuity (VA), intraocular pressure (IOP), refractive error, axial length (AL), and anterior chamber depth (ACD), was used to compare 30 adults with HM and 22 healthy controls (HC). Regional brain volumes and cortical thickness were analyzed in the fusiform gyrus (FuG), inferior temporal gyrus (ITG), middle temporal gyrus (MTG), superior temporal gyrus (STG), and occipital subregions including the calcarine cortex (Calc), cuneus (Cun), lingual gyrus (LiG), inferior occipital gyrus (IOG), middle occipital gyrus (MOG), and superior occipital gyrus (SOG). Results: Compared with HCs, HM patients demonstrated significant volumetric increases in the ITG and MTG regions (all p < 0.05), with the left ITG remaining significant after false discovery rate (FDR) correction. No significant volumetric differences were observed in the fusiform or occipital regions. In contrast, cortical thickness analyses revealed significant thinning in the fusiform gyrus and bilateral occipital subregions, including the calcarine cortex, cuneus, lingual gyrus, and middle occipital gyrus (p = 0.000–0.026, FDR-corrected). Cortical thickness in the fusiform and occipital regions showed negative correlations with AL and ACD and positive correlations with spherical equivalent. Conclusions: High myopia is associated with region-specific brain structural alterations, characterized by volumetric increases in temporal regions and cortical thinning in fusiform and occipital areas, indicating that HM-related neuroanatomical changes extend beyond the ocular system to involve central nervous system structures. Trial registration: Not applicable.