László Módis1, Achim Langenbucher, Berthold Seitz. 1. University of Debrecen, Medical and Health Science Centre, Department of Ophthalmology, Debrecen, Hungary. lmodis@dragon.klte.hu
Abstract
PURPOSE: To obtain anterior and posterior corneal shape, curvature, and thickness of normal human corneas. To provide a semiquantitative analysis of normal topography patterns of the anterior and posterior corneal surfaces. METHODS: Eighty-eight healthy corneas of 44 normal subjects were analyzed using the scanning-slit topography/pachymetry system. Anterior and posterior elevation and mean power (central and steepest spherical and cylindrical) values and pachymetry data were determined. Right eye values were submitted for primary analysis; however, a comparison between right and left eyes was made in addition to test the possible reliability of the system. RESULTS: There was no significant difference between right and left corneas in 28 evaluated parameters, except for anterior central cylindrical (P = 0.005) and steepest cylindrical (P = 0.017) mean power. The anterior central spherical mean power correlated inversely with the posterior central spherical mean power (r = -0.27, P = 0.04), and the anterior steepest spherical mean power value showed inverse correlation with the mean posterior steepest spherical value (r = -0.44, P = 0.001). The mean central thickness of the cornea was 593.7 +/- 54.19 microm at the center and was 578 +/- 50.53 microm at the thinnest point, which was localized in 41% (n = 18) of the cases in the inferotemporal quadrant. An oval-shaped pattern was the most characteristic feature of the anterior and posterior elevation, mean power, and pachymetry maps. CONCLUSION: Orbscan scanning-slit topography seems to be a reliable technique for the evaluation of normal corneas not only for anterior shape and curvature but also for a real pachymetry gradient recording.
PURPOSE: To obtain anterior and posterior corneal shape, curvature, and thickness of normal human corneas. To provide a semiquantitative analysis of normal topography patterns of the anterior and posterior corneal surfaces. METHODS: Eighty-eight healthy corneas of 44 normal subjects were analyzed using the scanning-slit topography/pachymetry system. Anterior and posterior elevation and mean power (central and steepest spherical and cylindrical) values and pachymetry data were determined. Right eye values were submitted for primary analysis; however, a comparison between right and left eyes was made in addition to test the possible reliability of the system. RESULTS: There was no significant difference between right and left corneas in 28 evaluated parameters, except for anterior central cylindrical (P = 0.005) and steepest cylindrical (P = 0.017) mean power. The anterior central spherical mean power correlated inversely with the posterior central spherical mean power (r = -0.27, P = 0.04), and the anterior steepest spherical mean power value showed inverse correlation with the mean posterior steepest spherical value (r = -0.44, P = 0.001). The mean central thickness of the cornea was 593.7 +/- 54.19 microm at the center and was 578 +/- 50.53 microm at the thinnest point, which was localized in 41% (n = 18) of the cases in the inferotemporal quadrant. An oval-shaped pattern was the most characteristic feature of the anterior and posterior elevation, mean power, and pachymetry maps. CONCLUSION: Orbscan scanning-slit topography seems to be a reliable technique for the evaluation of normal corneas not only for anterior shape and curvature but also for a real pachymetry gradient recording.
Authors: Michelle Samuel; Sara M Thomasy; Allison S Calderon; Philip H Kass; Keith Collins; Christopher J Murphy Journal: Vet Ophthalmol Date: 2018-06-21 Impact factor: 1.644