Relationship between visual field sensitivity and retinal nerve fiber layer thickness as measured by optical coherence tomography

PURPOSE. To evaluate the strength and pattern of the relationship between visual field (VF) sensitivity and retinal nerve fiber layer (RNFL) thickness as measured by StratusOCT (Carl Zeiss Meditec, Inc., Dublin, CA). METHODS. Three hundred eleven subjects -45 normal, 102 with preperimetric glaucoma (PPG), and 164 with primary open-angle glaucoma (POAG)-were enrolled in this cross-sectional study. The relationship between RNFL thickness and VF sensitivity, expressed as mean deviation (MD) and mean sensitivity (MS), were evaluated with linear and nonlinear regression models, and the coefficient of determination (R-2) was calculated. The association between RNFL/VF was described by bivariate Pearson correlation coefficients. RESULTS. The correlation of RNFL and the VF parameters MS and MD in normal and PPG eyes was not significant. In POAG eyes, RNFL and both MS (r = 0.733) and MD (r = 0.718) correlated significantly. Linear regression plots of MS or MD against RNFL thickness demonstrated a negligible degree of determination in normal (R-2 = 0.0378 and 0.0121, respectively) and PPG groups (R-2 = 0.0215 and 0.0151, respectively), whereas their relationship fit a curvilinear regression model (R-2 = 0.6947 and 0.723) in the POAG group. Receiver operating characteristic (ROC) curves describing the VF parameters and average RNFL thickness (AVG) were evaluated to differentiate PPG from POAG eyes. Repeated analysis with the best-performing test parameter, pattern standard deviation (PSD) (AUROC = 0.937) with a cutoff of 1.9 dB, showed that regression profiles in the POAG group with PSD > 1.9 dB maintained a strong curvilinear RNFL/VF relationship, whereas those with PSD > 1.9 dB exhibited a relationship almost indistinguishable from the PPG group. CONCLUSIONS. Evaluation of the structure-function relationship in normal subjects and those with PPG or POAG showed strong curvilinear regression in POAG eyes with PSD > 1.9 dB and RNFL AVG thickness below 70 mu m, whereas no correlation was detectable above these values.