Multi-meridional keratometry.

During conventional keratometry, the two principal meridia are identified and measurements of the anterior corneal curvature determined along these orientations. However, in cases of corneal irregularity, the principal meridia may be difficult to identify. Accordingly, the present study sought to evaluate two alternative procedures which do not require identification of the principal meridia. Instead, measurements of anterior corneal curvature were determined along either three or four preselected meridia and subsequently converted into the standard format for measurements of anterior corneal curvature. The study was performed on 25 visually normal subjects and the results compared with conventional two meridian keratometry findings. No significant differences were observed between the mean findings for the three and four meridian techniques. Furthermore, both procedures gave comparable results to the conventional two meridian method. Accordingly, multi-meridional keratometry may be valuable in cases of irregular astigmatism, for example produced by keratoconus or scarred corneas, since measurements can be obtained without the necessity for identification of the principal meridia.