Measurement of Retinal Thickness in Normal Subjects with Retinal Thickness Analyzer

The retinal thickness at posterior pole of normal subjects was mea-sured 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× 6 mm in size (approximately 20°, centered on the macula) at the poste-rior pole was scanned by using RTA to obtain images of 116 normal eyes of 77cases of various age group. The irnages 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 pm with no significant difference among the various age groups (P>0. 05).The thickness maps of the retina of 6 mm× 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.

Preliminary Studies on the Application of Retinal Thickness Analyzer in the Diagnosis of Glaucoma

The patients with glaucoma underwent the examination of retinal thickness analyzer (RTA) to explore the diagnostic value of RTA in glaucoma. The retina of 6 mm×6 mm size (approximately 20°, centered on the macula) at the posterior pole was scanned by using RTA to obtain the images in 35 eyes of 22 patients with glaucoma. The images were processed by using SAS software package. The retinal thickness in the patients with glaucoma showed diffuse or local thinning. Twenty seven eyes was definitely diagnosed as having glaucoma. There was a very significant difference in retinal thickness measurements by RTA between normal group and glaucomatous group ( P =0.0012). Except the measurements at the detected point 6 having no difference, the measurements at the detected point 3 showed a significant difference and the remaining 7 detected points presented a very significant difference between the two groups. Of the detected 9 points, the changes at the points 4, 8, and 9 were the most obvious. The discrete analysis was performed on the glaucomatous patients by a discriminant function established through the data at the detected points 4, 8 and 9 and the accurate estimate rate for the diagnosis of glaucoma was up to 80.77 %. The measurements of RTA examination was consistent with the results of the vision field test. It was suggested that diffuse or local thinning of retinal thickness exists in the patients with glaucoma. The temporal inferior arcuate fibers and the papillomacular bundle between the macular and optic nerve heads showed a serious damage. The sensitivity of RTA examination was higher than visual field test.