Use of Optimized Axial Lengths for IOL Power Calculations in Eyes With Long Axial Lengths
Patients with long axial lengths may experience a hyperopic surprise after cataract surgery. The purpose of this study was to review the refractive outcomes of cataract surgery using IOL calculations performed with optimized axial lengths as previously described by Wang et al.
This retrospective single-surgeon case series included eyes with long axial lengths (>25.0 mm) as determined by the IOL Master (Carl Zeiss Meditec, Inc). Axial length optimization was performed with the use of equations that adjust the measured axial length so as to improve the accuracy of IOL power calculation with the SRK/T formula. The target refraction for each eye (typically emmetropia or -1.00D) as well as the final IOL selected for implantation was recorded. Pre- and post-operative visual acuity and the automated refraction at 4-6 weeks after surgery were also documented.
24 eyes of 18 patients were included. The mean axial length was 26.86+/-0.83mm. After axial length optimisation, the IOL power selected to achieve target refraction was increased by a median of +0.50D (range 0.00D – +1.00D) over the original power calculation. All eyes had the Acrysof SA60AT (Alcon Laboratories, Inc) implanted during uncomplicated phacoemulsification. At 4-6 weeks after surgery, the difference between the actual spherical error versus the target spherical refraction was a median of -0.13D (range +0.75D to -1.00D). 83.3% were within + 0.50 of targeted spherical refraction, and only one eye was left significantly hyperopic (+0.75D) after surgery.
This study demonstrates that use of an optimised axial length with the SRK/T formula can minimise hyperopic surprise after cataract surgery in eyes with long axial lengths.