Topographic Characteristics of the Optic Nerve Head Measured with Scanning Laser Tomography in Normal Japanese Subjects

Abstract

Few studies have been performed regarding the topographic information obtained with the Heidelberg retina tomograph (HRT) in normal Japanese. In this study, we examined the factors influencing optic disc parameters and hemisphere symmetry obtained with the HRT in normal Japanese subjects. Mean values and the standard deviation range for the main HRT parameters were evaluated in 223 eyes of 223 normal Japanese subjects. The influence of age, sex, and disc size on HRT topographic data was analyzed. The superior and inferior hemisphere topographic parameters were compared. Disc area showed a significant difference by sex (P = 0.0493). Rim volume (r = -0.208, P = 0.019), height variation contour (r = -0.275, P = 0.001), and mean retinal nerve fiber layer (RNFL) thickness (r = -0.366, P = 0.001) declined with age. All parameters except height variation contour and mean RNFL thickness showed a clinically significant correlation with disc size (-0.159 < r < 0.719, P < 0.01). Cup parameters in the superior hemisphere were significantly greater than those in the inferior hemisphere. In contrast, rim parameters in the superior hemisphere were significantly smaller than those in the inferior hemisphere. Some factors, namely, sex, age, and disc size, affected the optic disc parameters in the HRT measurements. Possible parameter asymmetry between the two hemispheres should be considered in normal eyes.