Evaluation of angle kappa using the autorefractometer front monitor image

Purpose The aim of this study was to present a novel angle kappa (k) measurement method and grading scale using the autorefractometer front monitor image. Methods Two hundred sixty eyes of 130 subjects were included in the study. All eyes were evaluated using the front monitor image from an autorefractometer (ARFMI) (Canon, RK-F1, Japan). The distance from the center of the pupil to the visual axis on the ARFMI was measured using Image J software (http://rsbweb.nih.gov/ij). Sixty eyes of 30 subjects were evaluated using the Lens Star 900 (Haag-Streit AG, Koeniz, Switzerland), and Lens Star 900 angle-k values were compared with autorefractometer measurements to analyze the reliability of the method. Factors that may influence angle-k value were analyzed, and an ARFMI angle-k grading scale was developed and presented in the study. Results The mean ARFMI angle-k was 0.41 ± 0.22 mm, and the Lens Star 900 angle-k was 0.38 ± 0.24 mm. The Pearson correlation test was used to evaluate the reliability of the method, and there was a statistically significant positive correlation between the two methods (r: 0.628, p < 0.001). The mean ARFMI angle-k was higher in old and adult subjects when compared with young subjects, and the difference was statistically significant (p: 0.02 and p: 0.04, respectively). According to the ARFMI analysis, old subjects had narrow and nasally decentralized pupils when compared with young subjects, and the difference was statistically significant (p < 0.00 and p < 0.03, respectively). According to the ARFMI angle-k grading scale, 36.1% of subjects were grade 1, 38.3% were grade 2 on the x axis, and 58.5% were grade 1 on the y axis. Conclusions A novel angle-k measurement method and grading scale is presented in this study. In addition, the factors influencing the ARFMI angle-k and pupillary properties obtained from the ARFMI are evaluated. According to the results, angle-k and pupil properties may be evaluated using an easily evaluable, cost-effective device, which is present in every ophthalmic clinic.