AIM: To compare the consistency of angle Kappa and angle Alpha in age-related cataract eyes with three different instruments.

METHODS: Prospective study. Totally 60 eyes of 30 patients with age-related cataract from December 1 to December 30, 2020 were collected. After adapting to 10min in the darkroom before operation, the angle Kappa and angle Alpha were measured with iTrace, Lenstar 900 and IOL Master 700 biometric instruments, respectively. The difference and consistency of the three instruments were analyzed.

RESULTS: The results of angle Kappa measurement of iTrace, Lenstar 900 and IOL Master 700 were 0.25±0.13, 0.19±0.11, 0.21±0.11mm(F=1.903, P=0.155). The results of angle Alpha measurement of the three instruments were 0.31±0.11, 0.36±0.16, 0.36±0.14mm(F=2.999, P=0.052). The proportion of angle Kappa of the three instruments greater than 0.5mm is 3%, 2% and 2%, and the proportion of angle Alpha greater than 0.5mm is 5%, 15% and 22%. The distribution of angle Kappa and angle Alpha is mainly in the temporal side of both eyes. Compared with the angle Kappa distribution of both eyes, the temporal distribution ratio of angle Alpha is higher, and the distribution of angle Alpha measured by iTrace is closer than that of Lenstar 900 and IOL Master 700 along the horizontal line. There was a positive correlation between angle Alpha and angle Kappa measured by each instrument(r=0.2941, 0.4082, 0.5137; P=0.0226, P=0.0012, P<0.0001). The consistency of angle Kappa measurement results of three kinds of instruments was good, while that of angle Alpha measurement results was poor.

CONCLUSION: When making the decision of multifocal intraocular lens implantation before cataract surgery, the consistency of angle Alpha measured by Lenstar 900, IOL Master 700 and iTrace is poor, so it is necessary to compare and refer to the results of various instruments in clinical application. When the data of angle Alpha could not be obtained before cataract surgery, the angle Kappa measured with the three instruments could provide useful information for multifocal IOL implantation decision.