Accuracy of IOL Power Calculation Using Intraoperative Aberrometry System Compared With Holladay 2 Formula
Narrative Responses:
Purpose
To evaluate the predictability of intraocular lens (IOL) power calculation using the Optiwave Refractive Analysis (ORA) compared with the Holladay 2 formula in order to optimize cataract surgery refractive outcomes.
Methods
In a retrospective chart review, 53 eyes met inclusion criteria. Eyes with complicated cataract surgery and visual comorbidity limiting final visual acuity (<20/30) were excluded. Data collected included type of intraocular lens implanted, prior refractive surgery, post-operative refraction and predicted results of the ORA and Holladay 2 for the implant chosen. The data was stratified into 4 recipient subgroups (post-refractive, ReSTOR, monofocal, and toric). The main outcome measure was the absolute error, in diopters (D), between the predicated refractive goal of each formula and the measured spherical equivalent at the 1-month postoperative visit.
Results
The mean absolute error (MAE) was calculated for each formula and compared and analyzed using the paired t-test. Overall, the MAE was smaller with the ORA (0.30D) compared with the Holladay 2 (0.44D) (p=0.004, n=53). When broken down by subgroup, the MAE in the post-refractive, ReSTOR, monofocal and toric groups was 0.26D vs. 0.69D (p=0.002, n=13); 0.26D vs. 0.33D (p=0.146, n=24); 0.44D vs. 0.55D (p=0.088, n=3); and 0.40D vs. 0.39D (p=0.889, n=13), for the ORA and Holladay 2 respectively.
Conclusion
Overall the IOL power calculation using ORA was shown to be more precise than with Holladay 2. Only the post-refractive subgroup demonstrated statistically significant superiority of the ORA IOL power prediction. This data suggests that the ORA could serve as useful adjunctive method for calculating IOL power in post-refractive patients.