This study from the January issue of the American Journal of Ophthalmology used high-penetration optical coherence tomography (OCT) to evaluate choroidal thickness in patients with highly myopic normal-tension glaucoma (NTG). The results, obtained from measurements taken at multiple locations, indicate that the choroid is significantly thinner in patients with highly myopic NTG compared with myopic controls. The authors conclude that choroidal thinning is somehow related to highly myopic NTG and may be a useful diagnostic parameter for this condition.
The study included eight NTG patients (12 eyes) younger than 45 years old without any other ocular diseases, spherical equivalent refractive error between 6.0 and 12.0 D and axial length greater than 26.5 mm, and 12 controls.
They used high-penetration OCT to measure choroid thickness at the fovea, 2 mm superior, temporal, and inferior to the center of the optic nerve head, and 2 mm superior (superotemporal) and inferior (inferotemporal) to the temporal location.
Choroidal thickness in NTG patients was approximately 50 percent that of controls. Mean choroidal thickness in the NTG group was significantly thinner than in the control group at the fovea (166 vs. 276 µm, P < 0.001) and superior (172 vs. 241 µm, P < 0.05), superotemporal (161 vs. 244 µm, P < 0.01), temporal (110 vs. 161 µm, P < 0.01) and inferotemporal (115 vs. 159 µm, P < 0.05) to the optic nerve head. Stepwise analysis indicated that choroidal thickness at the fovea was the parameter most highly correlated with the development of highly myopic NTG.
The authors note that since the study included only cases of early disease, conclusions drawn from its results may be limited to early cases of glaucoma.