Comparison of the Angle Kappa Measured by Pentacam and Keratron Scout

Objective: To investigate and analyze the difference in angle Kappa measured by Pentacam and Keratron Scout in refractive surgery patients. Methods: One hundred ninety-six eyes of 98 patients screened for refractive surgery were enrolled in this case series study. Pupil diameters and angle Kappa expressed in rectangular coordinates were measured by Pentacam and Keratron Scout. Data differences and correlation between the two examinations were compared and analyzed by a paired t test and Pearson correlation analysis. Results: Pupil diameters measured by Pentacam and Keratron Scout were 3.17±0.44 mm, 3.19±0.53 mm (right eye), and 3.25±0.65 mm, 3.33±0.48 mm (left eye), respectively. The differences between the two instruments were not significant. The horizontal and vertical offset measured by the two instruments were not statistically different. There was a significant correlation in the offset of the angle Kappa measured by the two instruments (P<0.05). The correlation coefficients of the right eye horizontal offset, right eye vertical offset, left eye horizontal offset, left eye vertical offset were 0.966, 0.969, 0.956 and 0.913, respectively. Conclusion: There is no statistically significant difference between angle Kappa measured by Pentacam and Keratron Scout when pupil diameters are consistent. Both instruments can be used as a reference for the adjustment in angle Kappa in refractive surgery. Key words: Pentacam; Keratron Scout; pupil diameter; angle kappa