Could anatomical changes occurring with cataract surgery have a clinically significant effect on effective intraocular lens position?

PURPOSE

To assess if the calculation of the effective lens position (ELP) of two different monofocal intraocular lenses (IOLs) could be optimized by considering the potential anatomical changes occurring after cataract surgery.

METHODS

Prospective, descriptive, single-center study involving 472 eyes of 280 subjects (mean age 73.5 years) undergoing cataract surgery that were divided into two groups according to the IOL implanted: group 1330 eyes with AcrySof IQ SN60WF (Alcon), and group 2142 eyes with Akreos MI60L (Bausch + Lomb). Refractive and biometric changes were evaluated during a period of 6-month follow-up with an optical biometer (considering potential measurement artifacts). Comparison of ELP estimated with the SRK-T formula (ELP) and ELP calculated considering clinical real data was made (ELP).

RESULTS

Besides significant changes in refraction (p ≤ 0.020), a significant increase in anterior chamber depth (ACD) (p < 0.001) and a significant reduction in the axial length (AXL) (p < 0.001) were detected at 1 month after surgery. Mean 1-month postoperative AXL change was - 0.08 ± 0.06 and - 0.10 ± 0.11 mm in groups 1 and 2, respectively (p = 0.001), with no significant changes afterward. Mean difference between ELP and ELP was 0.17 ± 0.39 and - 0.23 ± 0.43 mm in groups 1 and 2, respectively (p < 0.001). A strong and statistically significant correlation of these differences with the prediction refractive error was found in both groups (group 1, r =  - 0.723; group 2, r =  - 0.819; p < 0.001).

CONCLUSIONS

The estimation of ELP using the SRK-T formula for the two IOLs evaluated may be optimized considering biometric changes with surgery, helping to understand better some problems of refractive unpredictability.