Evaluation of the choroidal thickness using high-penetration optical coherence tomography with long wavelength in highly myopic normal-tension glaucoma.

PURPOSE: To evaluate the choroidal thickness by high-penetration optical coherence tomography (OCT) using long wavelength in highly myopic normal-tension glaucoma (NTG).

DESIGN

Cross-sectional retrospective study.

SETTINGS: Institutional.

PARTICIPANTS

Twelve eyes from 8 patients under 45 years old, diagnosed as NTG without any other ocular diseases, spherical equivalent refractive error between -6 and -12 diopters, and axial length greater than 26.5 mm; and 12 eyes of matched healthy volunteers.

INTERVENTION: Choroid was imaged with prototype high-penetration OCT and its thickness was measured.

MAIN OUTCOME MEASURES: Choroidal thickness at the fovea and 5 locations: 2 mm superior, temporal, and inferior to the center of the optic nerve head, and 2 mm superior (superotemporal) and 2 mm inferior (inferotemporal) to the temporal location.

RESULTS

Overall, the choroidal thickness in the NTG group was approximately 50% that in controls. Mean choroidal thickness in the NTG group was significantly thinner in the control group at the fovea (166 vs 276 μm, P < .001), superior (172 vs 241 μm, P < 0.05), superotemporal (161 vs 244 μm, P < .01), temporal (110 vs 161 μm, P < .01), and inferotemporal (115 vs 159 μm, P < .05) to the optic nerve head. Stepwise analysis disclosed that the foveal choroidal thickness is the most influential factor on the occurrence of NTG (P < .0001, R(2) = 0.4).

CONCLUSIONS

Choroidal thickness in highly myopic NTG is significantly thinner than in controls, at least in some specific locations. Choroidal thinning is somehow related with highly myopic NTG and may be a useful diagnostic parameter for myopic NTG.