Evaluation of optical power integrity in toric and multifocal intraocular lenses

Implanting an intraocular lens (IOL) with an appropriate dioptric power is critical for achieving high-quality visual outcomes after cataract surgery. Discrepancies between labeled and actual dioptric power may affect IOLs selection and compromise refractive accuracy. This study aimed to evaluate the agreement between labeled and actual dioptric powers of commercially available toric and multifocal IOLs.

Spherical and cylindrical powers of toric IOLs, and spherical and additive powers of multifocal IOLs, were measured via an optical bench system based on the magnification method. Measured values were assessed for compliance with International Organization for Standardization (ISO) 11979-2 tolerance limits via two one-sided t-tests(TOST).

All three toric IOLs satisfied the ISO tolerance criteria for both spherical and cylindrical power (p < 0.05), with errors of 0.208 ± 0.170 D and 0.172 ± 0.206 D, respectively. The average absolute deviation across all toric measurements was 0.137 D. All four multifocal IOLs also met the ISO tolerance criteria for spherical and addition power (p < 0.05), with errors of 0.069 ± 0.041 D and 0.045 ± 0.044 D, respectively. The average absolute deviation in the multifocal group was 0.057 D.

These results confirm that both toric and multifocal IOLs comply with ISO standards for labeling accuracy. However, the greater variability observed in toric lenses highlights the importance of rotational alignment and precise manufacturing, which are critical for successful astigmatic correction.