Clinical outcomes and comparison of intraocular lens calculation formulas in eyes with long axial myopia

Abstract

Purpose: The purpose of this study was to report the clinical and refractive outcomes of eyes with long axial length (AL) and high myopia that underwent cataract surgery and compare the performance of intraocular lens (IOL) calculation formulae on these eyes.

Materials and methods: This retrospective cohort included 183 eyes that underwent cataract surgery from January 2010 to December 2018. Demographics, AL, postoperative best-visual acuities, IOL power data, and postoperative complications were recorded. Refractive outcomes were analyzed and absolute predicted errors were compared between five IOL calculation formulas.

Results: The mean age included in the study was 65.4 ± 9.39 years with a mean AL of 26.76 ± 1.75 mm. Postoperatively, the mean sphere, cylinder, and manifest refraction spherical equivalent were 0.22 D ± 0.54, -0.78 D ± 0.50, and - 0.16 D ± 0.50, respectively. The average IOL power implanted was 11.12 D ± 4.59 D. No intraoperative complications were encountered, but there was one incidence of retinal tear with detachment reported postoperatively (0.55%). The Kane formula had the lowest mean absolute predicted error (MAE). A significant positive correlation between increasing AL and MAE was seen in the Sanders, Retzlaff and Kraft-Theoretical (SRK-T) and Ladas formulae but not statistically significant when the Kane, Barrett Universal II, and the Emmetropia Verifying Optical (EVO) formulae were used.

Conclusion: Cataract surgery in eyes with long ALs and high myopia is safe with a low incidence of intraoperative and postoperative complications. The Kane, Barrett, and EVO formulae were equally accurate in calculating the IOL power and achieved the least amount of residual error postoperatively.

Keywords: Barrett; Emmetropia Verifying Optical; Kane; Ladas; SRK-T; cataract surgery; high myopia; intraocular lens formula; long axial length.

Figure 1

Correlation between axial length and absolute predicted error with axial length on the X-axis and absolute predicted error on the Y-axis ([a] SRK-T; [b] Barrett; [c] Kane; [d] Emmetropia Verifying Optical; [e] Ladas)