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. 2024 Aug 23;10(17):e36609.
doi: 10.1016/j.heliyon.2024.e36609. eCollection 2024 Sep 15.

IOL power calculation in long eyes: Selection of the best axial length adjustement factor using the most common formulas

Ferdinando Cione  1   2 , Maddalena De Bernardo  1 , Ilenia Di Paola  1 , Alessandro Caputo  2 , Mario Graziano  1 , Nicola Rosa  1
Affiliations

IOL power calculation in long eyes: Selection of the best axial length adjustement factor using the most common formulas

Ferdinando Cione et al. Heliyon. .

Abstract

Purpose: Comparing IOL power calculation formulas in long eyes (AL≥26.00 mm) to find the best axial length (AL) adjustment/IOL power calculation formula combination.

Design: Retrospective, comparative, case-series.

Participants: Patients with long eyes that underwent cataract surgery.

Methods: five-hundred-fifty-four eyes of 554 patients were examined before and after standard phacoemulsification without complications. Eyes were subdivided in 3 groups according to AL: 26.00≤AL<28.00 mm, 28.00≤AL<30.00 mm, AL≥30.00 mm. Eight formulas that do not require anterior chamber depth (ACD) were evaluated: Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO) 2.0, Ladas Super Formula (LSF), Hoffer Q, Holladay 1, SRKT, T2 and T2.2. The lens constant of ULIB database and IOLCon database were used. Each formula was analyzed by using uncorrected AL (ALu) and following AL adjustments: Wang-Koch 1 (wk1), wk2, wk polinomial (wk-pol), estimated Cooke modified axial length (CMALe) and ALc correcting factor.

Main outcome measures: Mean absolute error (MAE), median absolute error (MedAE) and percentage of eyes within ±0.50 and ± 1.00 diopters (D) of prediction error.

Results: T2-ALu gave best outcome when 26.00 mm ≤ AL<28.00 mm. LSF-ALu, BUII-ALu, EVO 2.0-ALu, Holladay 1-wk-pol and T2.2-CMALe represented valid alternatives. EVO 2.0-ALc gave best outcomes when 28.00 mm ≤ AL<30.00 mm. Other thick-lens or hybrid artificial-intelligence-vergence based formulas (BUII-ALu, LSF-CMALe) and Holladay 1-wk2 demonstrated greater reliability compared to thin lens-based formulas. EVO 2.0-CMALe gave best outcomes when AL≥30.00 mm. Holladay 1-wk-pol e T2.2-wk1 represented valid alternatives (all p < 0.050). LSF could fail in 50 % of cases without ACD when AL≥30.00 mm.

Conclusions: Choosing the best AL adjustment/IOL power calculation formula combination for each AL subrange, can improve refractive outcomes in patients with long eyes that undergo cataract surgery.

Keywords: Axial length; Axial length adjustments; IOL power calculation; IOL power formulas; Long eyes.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Fig. 1a: Box-Plot diagram with the comparison of refractive outcomes obtained from different Intraocular Lens (IOL) Power Calculation Formula/Axial Length (AL) combinations in Group 1 (26.00≤AL<28.00 mm–269 eyes). Fig. 1b: Bar Chart with the comparison of the percentage of eyes with refractive error <0.5D/1.0D among different IOL Power Calculation Formula/AL adjustment combinations in Group 1. Footnotes Box: Interquartile range (IQR); Thick line: Median; Whiskers: range of non-anomalous values; Dots: mild outlier values (values greater than 1.5 x IQR below Q1 or above Q3); Asterisks: extreme outlier values (values greater than 1.5 x IQR below Q1 or above Q3); BUII=Barrett Universal II; EVO = Emmetropia Verifying Optical; LSF=Ladas Super Formula; T2.2 = Refinement of Formula T2 by Idrobo-Robalino et al.; ALu=Uncorrected AL, CMALe = Cooke modified estimated AL; wk-pol = Polynomial AL correction according to Wang-Koch; PE= Predicted refractive error.
Fig. 2
Fig. 2
Fig. 2a: Box-Plot diagram with the comparison of refractive outcomes obtained from different Intraocular Lens (IOL) Power Calculation Formula/Axial Length (AL) combinations in Group 2 (28.00≤AL<30.00 mm–138 eyes) Fig. 2b: Bar Chart with the comparison of the percentage of eyes with refractive error <0.5D/1.0D among different IOL Power Calculation Formula/AL adjustment combinations in Group 2. Footnotes Box: Interquartile range (IQR); Thick line: Median; Whiskers: range of non-anomalous values; Dots: mild outlier values (values greater than 1.5 x IQR below Q1 or above Q3); Asterisks: extreme outlier values (values greater than 1.5 x IQR below Q1 or above Q3); BUII=Barrett Universal II; EVO = Emmetropia Verifying Optical; LSF=Ladas Super Formula; T2.2 = Refinement of Formula T2 by Idrobo-Robalino et al.; ALu=Uncorrected AL, ALc = AL correction according to De Bernardo et al. CMALe = Cooke modified estimated AL; wk1 = AL correction according to Wang-Koch; wk2 = AL correction update according to Wang-Koch. PE= Predicted refractive error.
Fig. 3
Fig. 3
Fig. 3a: Box-Plot diagram with the comparison of refractive outcomes obtained from different Intraocular Lens (IOL) Power Calculation Formula/Axial Length (AL) combinations in Group 3 (AL≥30.00 mm–141 eyes). Fig. 3b: Bar Chart with the comparison of the percentage of eyes with refractive error <0.5D/1.0D among different IOL Power Calculation Formula/AL adjustment combinations in Group 3. Footnotes Box: Interquartile range (IQR); Thick line: Median; Whiskers: range of non-anomalous values; Dots: mild outlier values (values greater than 1.5 x IQR below Q1 or above Q3); Asterisks: extreme outlier values (values greater than 1.5 x IQR below Q1 or above Q3); BUII=Barrett Universal II; EVO = Emmetropia Verifying Optical; LSF=Ladas Super Formula; T2.2 = Refinement of Formula T2 by Idrobo-Robalino et al.; CMALe = Cooke modified estimated AL; wk1 = AL correction according to Wang-Koch; wk2 = AL correction update according to Wang-Koch; wk-pol = Polynomial AL correction according to Wang-Koch; PE= Predicted refractive error.
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