Material and Methods: The right eyes of 68 healthy subjects were examined prospectively. The mean age of the subjects was 36.26±15.51 years. Keratometry measurements in the flat (K1) and steep (K2) meridians were taken with the IOLMaster in eyes with pre-dilatation and post-dilatation of the pupillas. Automated keratometer and rotating Scheimpflug imaging system measurements were obtained simultaneously, after pupil dilatation. The measurement differences between the devices were compared by analysis of variance and Friedman analysis of variance. The correlation between devices were evaluated by using Pearson correlation analysis.

Results: The K1/K2 readings of the IOLMaster were 43.37/44.33 diopters in pre-dilatation and 43.38/44.32 diopters in post-dilatation. The difference between keratometric values in pre- and post-dilataion pupilla were not statistically significant (p>0.05). The K1/K2 readings of the automated keratometer and Scheimpflug imaging system were 43.35/44.18 diopters and 43.12/44.07 diopters, respectively. The difference between the values was statistically significant (p≤0.0001) but the correlation among these three systems was strong (r=0.988, p<0.001 and r=0.989, p<0.001, respectively).

Conclusions: IOLMaster keratometric values in pre- and post- dilatation pupillas are similar but IOLMaster keratometric values can differ from automated keratometry and Scheimpflug imaging system. Keywords : Keratometry, IOLMaster, Scheimpflug imaging system, automated keratometer