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.