Scheimpflug and high-resolution magnetic resonance imaging of the anterior segment: a comparative study.

High-resolution imaging with a camera system built on the Scheimpflug principle has been used to characterize the geometry of the anterior segment of the adult human eye as a function of aging and accommodative state but is critically dependent on algorithms for correction of distortion. High-resolution magnetic resonance imaging (MRI), in contrast, provides lower-resolution information about the adult eye but is undistorted. To test the accuracy of the Scheimpflug correction methods used by Cook and Koretz [J. Opt. Soc. Am. A 15, 1473 (1998)]; [Appl. Opt. 30, 2088 (1991)], data on anterior chamber and segment lengths, as well as lens thickness and anterior and posterior curvatures, were compared with corresponding MRI data for adults aged 18-50 at 0 diopter accommodation. Excellent statistical agreement was found between the MRI and the Scheimpflug data sets with the exception of the posterior lens radius of curvature, which is less well defined than the other measurements in the Scheimpflug images. The considerable agreement between data obtained with MR and Scheimpflug imaging, two different yet complementary in vivo imaging techniques, validates the Scheimpflug correction algorithms of Cook and Koretz and suggests the capability of directly integrating information from both. A third, equivalent, data set obtained with a Scheimpflug-style camera system differs considerably from both Scheimpflug and MRI results in magnitude and age dependence, with negative implications for this alternative method and its correction procedures.