A comparative study of autokeratometric and Scheimpflug keratometric measurements of the anterior corneal surface: results for a single subject

Abstract

One purpose of the broader study was to determine whether keratometric measurements obtained with an autokeratometer (Nidek ARK-700) would be comparable with those measured using the Oculus Pentacam(model 70700). Ten healthy subjects without ocular abnormality, no previous or current contact lens wear or history of ocular surgery were recruited and at least 43 successive keratometric measurements were obtained for the right eye of each subject using both instruments, namely the autokeratometer and the Pentacam. This paper will concern itself with data from only one of the ten subjects involved, namely Subject 1. The corneal powers were analyzed using multivariate methods for analyzing dioptric power. Scatter plots and meridional profiles of skewness and kurtosis were used to compare the results for the two instruments. Mean dioptric powers in conventional and scientific notation were determined. The results for this subject indicated that there was a statistically significant difference between the autokeratometry and the Pentacam. Although the means between the two instruments were found to be significantly different at a 95% level of confidence, there was minimal clinical difference between the means of the two instruments. That is, this preliminary investigation suggests that in normal eyes, clinically, keratometric results obtained by means of an autokeratometer and a Pentacam are reasonably similar and can be used interchangeably.

Keywords

• Scheimpflug photography
• Pentacam
• keratometry
• autokeratometry
• corneal power and topography