Clinically relevant differences in the selection of toric intraocular lens power in normal eyes: preoperative measurement vs intraoperative aberrometry

James A Davison,¹ Sarah Makari,² Richard Potvin<sup>2

1</sup>Wolfe Eye Clinic, Marshalltown, IA, USA; ²Science in Vision, Akron, NY, USA

Purpose: To assess the value of intraoperative aberrometry (IA) in determining toric intraocular lens (IOL) power in eyes with no previous ocular surgery.
Patients and methods: This was a retrospective data review at one US clinical site of eyes that underwent uncomplicated cataract surgery with toric IOL implantation where standard preoperative and IA measurements were available. Calculated IOL sphere and cylinder powers and orientation were compared based on the measurement method and the postoperative refraction, using both actual and simulated (back-calculated) results. Comparisons were between the surgeon’s preoperative calculations, IA measurements, the actual IOL implanted and results from the Barrett toric calculator.
Results: There was no significant difference (p>0.7) in the number of eyes expected to have, or having, a spherical equivalent refraction within 0.50D of the target between Actual (92%), IA (93%) or Preoperative calculation results (86%). The percentage of eyes with expected residual refractive astigmatism ≤0.50D was significantly higher for the IA vs Preoperative calculations (75% vs 53%, p<0.01). There was no significant difference in expected results between the Actual, IA and Barrett toric calculations (p>0.65).
Conclusion: Modern IOL calculations for sphere produced results comparable to those achieved with IA. The value of IA in determining IOL cylinder power and orientation was more evident when comparing expected results between IA and a preoperative method based on measured total corneal astigmatism than when comparing to expected results from the Barrett toric calculator.

Keywords: ORA, refraction, prediction error, IOL power calculation, astigmatism, toric IOL