Effect of the kappa angle on depth of focus after implantation of the TECNIS Symfony intraocular lens.

Purpose: To evaluate the clinical effect of TECNIS Symfony intraocular lens (IOL) implantation and identify the effect of kappa angle on the depth of focus (DOF) after implantation.

Methods: This prospective clinical study included consecutive patients who underwent cataract surgery and TECNIS Symfony IOL implantation at the Daqing Oilfield General Hospital from January 2019 to September 2019. Patients were divided into three groups according to the preoperative kappa angle (r): A (0 < r ≤ 0.2), B (0.2 < r ≤ 0.4), and C (r > 0.4). Uncorrected visual acuity was performed preoperatively and at 7 days, 1 month, and 3 months postoperatively. Synthetical optometry, higher-order aberrations, and defocus examinations were performed at 3 months postoperatively. Single-factor analysis of variance and Spearman correlation coefficient were used for data analysis.

Results: The uncorrected visual acuity values of the three groups were significantly improved postoperatively, compared with preoperative values (p < 0.001). Three months postoperatively, the best-corrected visual acuity values of the three groups were 0.11 ± 0.02 logarithm of the minimum angle of resolution (logMAR), 0.09 ± 0.03 logMAR, and 0.11 ± 0.03 logMAR, respectively. Spherical equivalent (SE) values were 0.37 ± 0.08 D, 0.41 ± 0.06 D, and 0.42 ± 0.06 D, respectively. Best-corrected visual acuity and SE did not significantly differ among the three groups (F = 1.254, p = 0.135; F = 0.849, p = 0.228). There was no significant difference in SE between the three groups (F = 1.658, p = 0.312). Moreover, higher-order aberrations did not significantly differ among the three groups (p > 0.05). The kappa angle was negatively correlated with the postoperative DOF (r = -4.341, p = 0.026). Three months postoperatively, 54.55% of patients exhibited DOF ≥ 3 D, while 92.42% of patients exhibited DOF ≥ 2 D. The ranges of DOF in the three groups were 3.18 ± 0.27 D, 2.83 ± 0.80 D, and 2.57 ± 0.89 D, respectively; the difference among the three groups was statistically significant (F = 5.689, p = 0.037).

Conclusion: Most patients achieved full-range vision after TECNIS Symfony IOL implantation, but the DOF narrowed for those with an excessively large kappa angle, which indicates a need for careful selection.