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Peripheral keratometry - accuracy and reliability in comparison to a corneal topography system, for application in rigid contact lens fitting

1 May 1998


Peripheral keratometry was once a widely used practice in optometry. The technique fell out of vogue in the mid-1960s when questions arose concerning its accuracy. In this project, the accuracy of peripheral keratometry was reevaluated on 162 normal non-contact lens-wearing eyes. The results obtained by a Reichert keratometer and a fabricated plastic peripheral fixation device were statistically compared to data obtained by the Humphreys MasterVue corneal keratoscopic mapping system. Patients were asked to fixate on a point 13mm from the center of a plastic disc overlaid onto the keratometer mire plate. The curvature value achieved with this fixation was then compared to the curvature value taken 3.0mm from the center of the corneal topographic map. Results show a high correlation(> 90%) between the mid-peripheral corneal curvature data obtained with the peripheral keratometry disc and data obtained by the corneal mapping system 3.0mm from center. Results from this study also indicate that the keratometer, when used with a peripheral fixation device, can yield data just as accurate as the corneal topography system (p-value > 0.05). Clinical application of this procedure could prove beneficial to the "general11 optometric practitioner who fits rigid contact lenses but may not be able to afford an expensive corneal mapping system.


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