Optic Disc Rim Area Is Related to Disc Size in Normal Subjects

To the Editor. —We read with great interest the recent article by Caprioli and Miller.1The article provides muchneeded information on relationships between topographic optic disc measurements and disc size in computerized optic disc image analysis. The authors should be congratulated for this as well as for their previous pioneering works2,3on optic disc analysis using the Rodenstock analyzer. With due respect, however, we would like to make the following points. We have found two discrepancies that, while neither critical nor diminishing the significance and the validity of their work, may need to be clarified. In the "Results" section, the regression line in Fig 3 does not correspond to the equation for the regression line Caprioli and Miller have calculated (Rim area = 1.36 × disc area −1.19 mm2). Our approximate calculation