Structure-function relationships of circumpapillary choroidal thickness in normal-tension glaucoma with and without high myopia.

PURPOSE: To evaluate the relationship between circumpapillary choroidal thickness (cpChT) and visual field sensitivity (VFS) in normal-tension glaucoma (NTG) eyes, and to determine whether high myopia (HM) modifies these structure-function associations. METHODS: Retrospective observational study. Two hundred seventy-eight eyes of 278 NTG (134 HM eyes and 144 eyes without HM) were included. HM was defined as axial length > 26.0 mm. CpChT was manually measured at a 2.25 mm radius from the Bruch's membrane opening (BMO) center on radial circumpapillary optical coherence tomography (OCT) scans. Multivariable linear regression models were constructed with global and Garway-Heath sectoral cpChT as dependent variables and corresponding 24- 2 and 10 - 2 VFS as independent variables, adjusting for age, axial length, and BMO area, to assess the association between cpChT and VFS. RESULTS: In the overall NTG cohort, global, superior nasal and superior temporal cpChT were significantly positively associated with corresponding 24 - 2 VFS (p = 0.038, 0.033, 0.039, respectively). These associations remained significant in NTG eyes without HM (p = 0.039, 0.039, 0.020, respectively), but were not observed in eyes with HM. For central visual function, the inferior half cpChT was significantly associated with corresponding 10 - 2 VFS (p = 0.048) in the overall NTG cohort. In eyes without HM, significant associations were observed for global, superior half, and temporal cpChT with 10 - 2 VFS (p = 0.047, 0.047, 0.032, respectively), whereas no significant cpChT-VFS relationships were detected in HM eyes. Global cpChT was associated with age and axial length in the overall NTG cohort and in NTG subgroups with and without HM (all p < 0.05). However, global cpChT was associated with BMO area only in the HM eyes (p = 0.029). CONCLUSION: CpChT demonstrates modest, sector-dependent associations with both peripheral and central VFS in NTG after accounting for key anatomic confounders. These associations are attenuated in HM eyes, suggesting that myopia-related structural remodeling alters choroidal-functional coupling.