IOL power calculations after LASIK or PRK: Barrett True-K biometer-only calculation strategy yields equivalent outcomes as a multiple formula approach

Ferguson, Tanner J.; Downes, Rachel A.; Randleman, J. Bradley

doi:10.1097/j.jcrs.0000000000000883

Cited by 19 publications

(15 citation statements)

References 27 publications

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“…Many of these studies support and reinforce the findings of previously published literature. For instance, Ferguson et al [39] and Yao et al [7] both concluded that the Barrett True-K (No History) method was the most accurate among no-history formulas (including Haigis-L) for postmyopic LRS eyes, corroborating earlier research. Gasparian et al [40] found that intraoperative aberrometry had a lower mean absolute error (MAE) than Barrett True-K for postmyopic LRS eyes [41] reaffirmed the efficacy of correction factors by using Jarade's Index and Jarade's Formula in several conventional formulas to achieve superior refractive outcomes compared to other IOL power calculation formulas, including Haigis-L and Barrett True-K. Another study achieved excellent outcomes using a raytracing approach with corrections to axial length [42].…”

Section: Key Pointssupporting

confidence: 57%

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An update on intraocular lens power calculations in eyes with previous laser refractive surgery

Savage,

Pantanelli

2023

Current Opinion in Ophthalmology

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Purpose of review There is an ever-growing body of research regarding intraocular lens (IOL) power calculations following photorefractive keratectomy (PRK), laser-assisted in-situ keratomileusis (LASIK), and small-incision lenticule extraction (SMILE). This review intends to summarize recent data and offer updated recommendations. Recent findings Postmyopic LASIK/PRK eyes have the best refractive outcomes when multiple methods are averaged, or when Barrett True-K is used. Posthyperopic LASIK/PRK eyes also seem to do best when Barrett True-K is used, but with more variable results. With both aforementioned methods, using measured total corneal power incrementally improves results. For post-SMILE eyes, the first nontheoretical data favors raytracing. Summary Refractive outcomes after cataract surgery in eyes with prior laser refractive surgery are less accurate and more variable compared to virgin eyes. Surgeons may simplify their approach to IOL power calculations in postmyopic and posthyperopic LASIK/PRK by using Barrett True-K, and employing measured total corneal power when available. For post-SMILE eyes, ray tracing seems to work well, but lack of accessibility may hamper its adoption.

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Section: Key Pointssupporting

confidence: 57%

“…Ferguson et al [39] conducted a study comparing the accuracy of various IOL power calculation formulas in 143 eyes, including 47 eyes that underwent posthyperopic laser refractive surgery. The study found that Barrett True-K (No History) was the most accurate (Table 2).…”

Section: Recent Updates To the Literature For Posthyperopic Laser Ref...mentioning

confidence: 99%

An update on intraocular lens power calculations in eyes with previous laser refractive surgery

Savage,

Pantanelli

2023

Current Opinion in Ophthalmology

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“…BTK, developed based on BUII, has demonstrated good performance in various retrospective consecutive case series studies. Ferguson et al reported that BTK outperformed other ASCRS formulas in both myopic and hyperopic post laser refractive surgery patients (96 post myopic eyes and 47 post hyperopic eyes) 23 . Abula a et al found that BTK had signi cantly smaller prediction errors and a higher percentage of eyes within ± 0.50 D than the Shammas and Haigis-L formulas in postmyopic LASIK cases (80 postmyopic eyes) 24 .…”

Section: Discussionmentioning

confidence: 99%

Comparison of the accuracy of 9 intraocular lens power calculation formulas after SMILE in Chinese myopic eyes

Li,

Yuan,

Yang

et al. 2023

Preprint

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As of 2021, over 2.8 million cases of small incision lenticule extraction (SMILE) procedures had been performed in China. However, there remains limited knowledge regarding the selection of intraocular lens (IOL) power calculation formulas for post-SMILE cataract patients. This study included 52 eyes of 26 myopic patients from northern China who underwent SMILE at Tianjin Eye Hospital from September 2022 to February 2023 and was designed to investigate the performance of multiple IOL calculation formulas in post-SMILE patients using a theoretical surgical model. We compared the postoperative results obtained from three artificial intelligence (AI)-based formulas and six conventional formulas provided by the American Society of Cataract and Refractive Surgery (ASCRS). These formulas were applied to calculate IOL power using both total keratometry (TK) and keratometry (K) values, and the results were compared to the preoperative results obtained from the Barrett Universal II (BUII) formula in SMILE cases. Among the evaluated formulas, the results obtained from Emmetropia Verifying Optical 2.0 Formula with TK (EVO-TK) (0.40 ± 0.29 D, range 0 to 1.23 D), Barrett True K with K (BTK-K, 0.41 ± 0.26 D, range 0.01 to 1.19 D), and Masket with K (Masket-K, 0.44 ± 0.33 D, range 0.02 to 1.39 D) demonstrated the closest proximity to BUII. Notably, the highest proportion of prediction errors within 0.5 D was observed with BTK-K (71.15%), EVO-TK (69.23%), and Masket-K (67.31%), with BTK-K showing a significantly higher proportion compared to Masket-K (p < 0.001). Our research indicates that in post-SMILE patients, EVO-TK, BTK-K, and Masket-K may yield more accurate calculation results. At the current stage, AI-based formulas do not demonstrate significant advantages over conventional formulas. However, the application of historical data can enhance the performance of these formulas.

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“…However, in another study, it was found that Barrett True-K was not statistically better than Shammas, Wang-Koch-Maloney, Haigis-L, and the average, minimum, and maximum values offered by the ASCRS calculator, although a type 2 error was not controlled in this study 41 . Ferguson et al observed that Barrett True-K achieved the lowest MAE among all formulae under test in both myopic and hyperopic refractive surgery, although the result was not inferior to the ASCRS multiple formula approach 42 . While results of studies slightly vary in the performance regarding Haigis-L and Barrett True-K, all studies have found them to be accurate methods of IOL calculation in post-LVC eyes.…”

Section: Methods For Intraocular Lens Power Calculation In Eyes With ...mentioning

confidence: 99%

Biometry and Intraocular Lens Power Calculation in Eyes with Prior Laser Vision Correction (LVC) – A Review

Wendelstein

Heath

Riaz

et al. 2022

Klin Monbl Augenheilkd

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Background An intraocular lens (IOL) calculation in eyes that have undergone laser vision correction (LVC) poses a significant clinical issue in regards to both patient expectation and accuracy. This review aims to describe the pitfalls of IOL power calculation after LVC and give an overview of the current methods of IOL power calculation after LVC. Review Problems after LVC derive from the measurement of anterior corneal radii, central corneal thickness, asphericity, and the predicted effective lens position. A central issue is that most conventional 3rd generation formulas estimate lens position amongst other parameters on keratometry, which is altered in post-LVC eyes. Conclusion An IOL power calculation results in eyes with prior LVC that are notably impaired in eyes without prior surgery. Effective corneal power including anterior corneal curvature, posterior corneal curvature, CCT (central corneal thickness), and asphericity is essential. Total keratometry in combination with the Barrett True-K, EVO (emmetropia verifiying optical formula), or Haigis formula is relatively uncomplicated and seems to provide good results, as does the Barrett True-K formula with anterior K values. The ASCRS ( American Society of Cataract and Refractive Surgery) calculator combines results of various formulae and averages results, which allows a direct comparison between the different methods. Tomography-based raytracing and the Kane and the Castrop formulae need to be evaluated by future studies.

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IOL power calculations after LASIK or PRK: Barrett True-K biometer-only calculation strategy yields equivalent outcomes as a multiple formula approach

Abstract: Using the Barrett True-K integrated into the biometer provided equivalent outcomes vs a multiple formula approach for IOL power calculations in both postmyopic and posthyperopic refractive surgery eyes.

Cited by 19 publications

References 27 publications

An update on intraocular lens power calculations in eyes with previous laser refractive surgery

An update on intraocular lens power calculations in eyes with previous laser refractive surgery

Comparison of the accuracy of 9 intraocular lens power calculation formulas after SMILE in Chinese myopic eyes

Biometry and Intraocular Lens Power Calculation in Eyes with Prior Laser Vision Correction (LVC) – A Review

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