Morphologic Changes in the Lamina Cribrosa Upon Intraocular Pressure Lowering in Patients with Normal Tension Glaucoma

PURPOSE. The purpose of this study was to investigate whether the lamina cribrosa (LC) curve changes in response to intraocular pressure (IOP) reduction following administration of topical ocular hypotensive eye drops in eyes with normal tension glaucoma (NTG). METHODS. Ninety-three eyes of 93 patients with treatment naive NTG at initial examination and with >= 20% reduction from baseline IOP following administration of topical ocular hypotensive eye drops were included. Serial horizontal B-scan images of the optic nerve head (ONH) were obtained from each eye using enhanced depth imaging spectral domain optical coherence tomography (OCT) before and 1 year after IOP-lowering treatment. The LC curvature in each eye was assessed by measuring the LC curvature index (LCCI) in horizontal OCT B-scan images obtained at three (superior, central, and inferior) locations spaced equidistantly across the vertical optic disc diameter before and after IOP-lowering treatment. We evaluated the OCT detectible change in the LC curvature based on the interval change of LCCI to exceed the intersession standard deviation of 1.96 times and factors associated with the magnitude of the LCCI change in the eyes showing significant LC change. RESULTS. IOP decreased from 15.7 +/- 2.5 mm Hg at baseline to 11.2 +/- 1.7 mm Hg after topical glaucoma medication. Among the 93 subjects, 62 (66.7%) eyes showed the significant reduction of the LCCI (interssetional change over 1.5) after the treatment; greater interssessional change of the LCCI after IOP reduction was associated with younger age (P = 0.020) and larger baseline LCCI (P < 0.001). CONCLUSIONS. The OCT detectible changes in LC curvature occurred in response to a modest decrease in the IOP in the naive NTG eyes. The therapeutic benefit of these changes need to be assessed in longitudinal studies.