Refractive Accuracy of Barrett True-K vs Intraoperative Aberrometry for IOL Power Calculation in Post-Corneal Refractive Surgery Eyes

Abstract

Purpose: To compare the refractive predictability of intraoperative aberrometry (IA, ORA, Alcon) and Barrett True-K/Universal II formulas for intraocular lens (IOL) power calculations in post-corneal refractive surgery and normal eyes. Methods: Retrospective study of normal and post-corneal refractive surgery eyes that underwent cataract surgery with IA at tertiary academic center. Preoperatively, IOL power calculations were performed using Barrett Universal II (normal eyes) or Barrett True-K (post-corneal refractive surgery eyes) formulas. Intraoperatively, aphakic IA measurements were used for IOL power calculations. Mean absolute refractive prediction error (MAE) and the percentage of eyes with prediction error within ±0.50, ±0.75 and ±1.00 D were calculated. Refractive predictability was also evaluated in short, normal, and long eyes. Results: Two hundred and seventy-three eyes were included in the analysis. No statistically significant differences were observed between the MAE of preoperative formulas and IA for post-hyperopic laser vision correction (LVC), post-myopic LVC, post-radial keratotomy (RK) and normal eyes. For prediction error within ±0.5 D in post-corneal refractive surgery eyes, range of agreement between Barrett True-K and IA ranged from 28% (7/25) of the time in post-RK eyes to 49% (40/81) of the time in post-hyperopic LVC; the corresponding value for Barrett Universal II/IA was 62% (64/103) in normal eyes. When there was disagreement, IA outperformed Barrett True-K in post-hyperopic LVC eyes and Barrett formula outperformed IA in post-myopic LVC, post-RK, and normal eyes. Conclusion: IA appears to be comparable to Barrett formulas for IOL power calculations in post-corneal refractive surgery and normal eyes. In post-hyperopic LVC, IA yields better results compared to Barrett True-K formula; in real-life scenarios, IA reveals statistical advantage over the Barrett True-K no history formula for eyes post-hyperopic LVC.

Refractive Outcomes Following Trifocal Intraocular Lens Implantation in Post-Myopic LASIK and PRK Eyes

“… 13 , 14 However, there are also reports of minimal difference in absolute prediction error between preoperative planning and IA. 15–18 In addition, the percentages of eyes with absolute prediction error of 0.5 D or less was greater in this study for both IA and preoperative planning compared to other studies of post-LVC eyes with non-trifocal 6 , 19 and trifocal 7 , 8 IOLs. However, the prediction error results in this study are comparable to the study by Cobo-Soriano et al 9 that evaluated a large number of post-LVC eyes implanted with a trifocal IOL.…”

Intraoperative aberrometry: an update on applications and outcomes

“…Subsequent studies have also shown benefit of intraoperative aberrometry relative to these formulas [49,50]. However, in multiple studies, intraoperative aberrometry has been shown to have similar refractive outcomes to the Barrett True-K formula (including Barrett True-K no-history formula), [28 ▪ ,50,51], and in one study, the Barrett True-K formula had a lower mean absolute error than intraoperative aberrometry [45]. Most frequently (including in large cohorts), the mean absolute prediction error of intraoperative aberrometry in post-myopic ablation eyes has been reported as approximately 0.4D [20 ▪▪ ,29,48,50] but was approximately 0.60D in two studies [28 ▪ ,45].…”

“…There are only a few large intraoperative aberrometry studies [20 ▪▪ ,28 ▪ ,31] in patient cohorts that include both typical/routine cases (patients whose axial length is not extreme and who do not have a history of refractive surgery) and less typical eyes. Consequently, there is relatively little data to extrapolate to the broad population of all-comers undergoing cataract surgery.…”

“…Post-myopic ablation patients are the largest subset of post-refractive patients undergoing cataract surgery, and early approaches to IOL calculation in these patients were unreliable [48]. There has been significant interest in using intraoperative aberrometry in post-myopic ablation patients to improve outcomes, and multiple studies have examined utility in these patients [20 ▪▪ ,28 ▪ ,29,42,45–51,55]. In fact, the ORA device was initially validated based on a study of its use in post-myopic ablation eyes [48].…”

Intraocular lens power calculation in eyes with previous corneal refractive surgery

“…Also, in this retrospective study, no significant difference in MAE could be shown: 0.71 D Barrett True K and 0.89 D IA. 45 …”