Relationship Between Macular Inner Retinal Layer Thickness and Corresponding Retinal Sensitivity in Normal Eyes

PURPOSE. The correlation between standard automated perimetry (SAP) sensitivity and macular inner retinal layer thickness in eyes with glaucoma is well known. We examined whether the corresponding correlation is also significant in normal eyes. METHODS. One eye of each of 195 normal subjects was included. The average thickness of the macular ganglion cell-inner plexiform layers (GCIPL) and the macular retinal nerve fiber layer/GCIPL (ganglion cell complex, GCC) in four regions with 0.6-mm-diameter circular area corresponding to the four central test points of the Humphrey Field Analyzer 24-2 test program, adjusted for ganglion cell displacement, were measured using spectral-domain optical coherence tomography (SD-OCT) and correlated to the mean SAP sensitivity (in 1/Lambert scale) at the corresponding test points with a multiple regression analysis using age, refraction, disc size, sex, and laterality of the eye as other explanatory variables. RESULTS. In normal eyes, GCIPL and GCC thickness (in micrometers) showed significant correlation to SAP sensitivity in corresponding areas, with partial regression coefficients of 0.0016 (P = 0.036) and 0.0022 (P = 0.023), respectively. Other significantly correlated factors were age and GCIPL (-0.18, P = 0.000), age and GCC (-0.20, P = 0.000), and refraction and GCIPL (0.92, P = 0.012). Similar analyses at each of the four test points yielded essentially the same results, although partial correlation coefficients were not always significant. CONCLUSIONS. A thicker macular GCIPL or GCC was weakly but significantly associated with higher SAP sensitivity in the corresponding macular region in normal eyes.