Focal relationship between structure and function within the central 10 degrees in glaucoma.

Abstract

To investigate which measurements of inner macular thickness are the most useful for evaluating the focal relationship with visual sensitivity within the central 10° in glaucoma and which layers require correction for retinal ganglion cell (RGC) displacement. Sixty eyes of 60 subjects with glaucoma were included. Sensitivity of each test point of 10-2 standard automated perimetry was compared with the thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), GCL+ inner plexiform layer (IPL), and RNFL+GCL+IPL (GCC), with and without RGC displacement, using Spearman's rank correlation coefficients. Visual sensitivity was evaluated by unlogged 1/Lambert (1/L) values. Retinal nerve fiber layer thickness correlated significantly with the sensitivities of all test points except for some in the papillomacular bundle region when adjusting for RGC displacement (rs = 0.287-0.767, P < 0.05). In the central 5.8°, the GCL and (GCL+IPL) thickness correlated significantly with the sensitivities of all test points when adjusting for RGC displacement (GCL: rs = 0.363-0.729, P < 0.01; (GCL+IPL): rs = 0.359-0.715, P < 0.01). The GCC thickness correlated significantly with the sensitivities of all 68 test points when adjusting for RGC displacement (rs = 0.359-0.767, P < 0.01). RGC displacement improved the correlation between sensitivity and GCL, (GCL+IPL), and GCC in the central 4 points (GCL: rs = from 0.270-0.470 to 0.421-0.540; (GCL+IPL): rs = from 0.195-0.450 to 0.381-0.549; GCC: rs = from 0.132-0.449 to 0.359-0.562). The GCC is the most useful parameter to evaluate structure and function within the central 10° in glaucoma. Adjusting for RGC displacement is essential to evaluate the relationship between structure of the GCL-related layer and function at the central macula.