Measurement of retinal thickness in normal subjects with retinal thickness analyzer.

The retinal thickness at posterior pole of normal subjects was measured by using retinal thickness analyzer (RTA) to determine the values of retinal thickness and to establish map of retinal thickness in normal subjects. The retina of 6 mm x 6 mm in size (approximately 20 degrees, centered on the macula) at the posterior pole was scanned by using RTA to obtain images of 116 normal eyes of 77 cases of various age group. The images were processed by a computer to obtain the retinal thickness values and the thickness map of this location. The data were analyzed with SAS software package. The mean retinal thickness was 171.77 +/- 26.13 microns with no significant difference among the various age groups (P > 0.05). The thickness maps of the retina of 6 mm x 6 mm size at the posterior pole around the macula rendered a "U"-shaped pattern, extending from the disc to the superior and inferior of the fovea. The retina was found to be thin at temporal side of the fovea, with the thinnest area being at the macula central fovea. The U-shaped pattern of the retinal thickness maps was well in agreement with the topography of the ganglion cells and the retinal nerve fibers in human retina. The measurement of the retinal thickness by RTA reflected the changes in the layers of ganglion cells and the retinal nerve fiber. Each scanning session of RTA examination can yield multiple optical cross-section images of the retina and obtain retinal thickness maps of posterior pole of living eyes.