Determining the Theoretical Effective Lens Position of Thick Intraocular Lenses for Machine Learning–Based IOL Power Calculation and Simulation

Gatinel, Damien; Debellemanière, Guillaume; Saad, Alain; Dubois, Mathieu; Rampat, Radhika

doi:10.1167/tvst.10.4.27

Cited by 27 publications

(25 citation statements)

References 37 publications

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“…Paraxial optics formulas for calculating the respective optical powers and principal plane positions of the cornea and IOL, modeled as thick lenses, and the resultant power and principal plane positions have been reviewed in a previous publication. 12 Herein, we describe an explicit formula allowing back-calculation of the theoretical position of the principal object plane of an IOL. In what follows, the formulas are clearly reported for a pseudophakic eye modeled as thick lenses with four refractive surfaces and distinct refractive indices between the aqueous and vitreous humor ( Fig.…”

Section: Methodsmentioning

confidence: 99%

Theoretical Relationship Among Effective Lens Position, Predicted Refraction, and Corneal and Intraocular Lens Power in a Pseudophakic Eye Model

Gatinel

Debellemanière

Saad

et al. 2022

Trans. Vis. Sci. Tech.

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Purpose To ascertain the theoretical impact of anatomical variations in the effective lens position (ELP) of the intraocular lens (IOL) in a thick lens eye model. The impact of optimization of IOL power formulas based on a single lens constant was also simulated. Methods A schematic eye model was designed and manipulated to reflect changes in the ELP while keeping the optical design of the IOL unchanged. Corresponding relationships among variations in ELP, postoperative spherical equivalent refraction, and required IOL power adjustment to attain target refractions were computed for differing corneal powers (38 diopters [D], 43 D, and 48 D) with IOL power ranging from 1 to 35 D. Results The change in ELP required to compensate for various systematic biases increased dramatically with low-power IOLs (less than 10 D) and was proportional to the magnitude of the change in refraction. The theoretical impact of the variation in ELP on postoperative refraction was nonlinear and highly dependent on the optical power of the IOL. The concomitant variations in IOL power and refraction at the spectacle plane, induced by varying the ELP, were linearly related. The influence of the corneal power was minimal. Conclusions The consequences of variations in the lens constant mainly concern eyes receiving high-power IOLs. The compensation of a systematic bias by a constant increment of the ELP may induce a nonsystematic modification of the predicted IOL power, according to the biometric characteristics of the eyes studied. Translational Relevance Optimizing IOL power formulas by altering the ELP may induce nonsystematic modification of the predicted IOL power.

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Section: Methodsmentioning

confidence: 99%

Theoretical Relationship Among Effective Lens Position, Predicted Refraction, and Corneal and Intraocular Lens Power in a Pseudophakic Eye Model

Gatinel

Debellemanière

Saad

et al. 2022

Trans. Vis. Sci. Tech.

Self Cite

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“…Studies attributed 35.5% of non-systematic predictive errors to the effective lens position (ELP), and the refinement of the second-eye PE may be attributable to the revision of remaining errors from the ELP and the inter-ocular symmetry to some extent [15,18]. Although several new formulas used more biometric variables or optical parameters such as LT and CD to predicate the ELP, the accurate prediction of the ELP remains the major obstacle in formula calculation, particularly in cataract patients with long AL [34,35].…”

Section: Discussionmentioning

confidence: 99%

Comparison of Formula-Specific Factors and Artificial Intelligence Formulas with Axial Length Adjustments in Bilateral Cataract Patients with Long Axial Length

Wang

Feng

et al. 2022

Ophthalmol Ther

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Introduction: To evaluate and compare the effectiveness for reducing the prediction error (PE) of the second eye using formula-specific factors, artificial intelligence (AI) formulas (PEARL-DGS and Kane), and the Cooke-modified axial length (CMAL) methods in bilateral cataract patients with long axial length (AL). Methods: A total of 98 patients with long AL who underwent sequential bilateral cataract surgeries were retrospectively enrolled. The second-eye IOL power was calculated by the formula-specific factors, AI formulas, and CMAL methods when the first eye suffered from refraction surprise. The correction factors of eight formulas were calculated by regression analysis.Results: There was a significant correlation between bilateral preoperative biometric parameters (P \ 0.05) as well as bilateral PE (P \ 0.05). The Kane formula displayed the lowest median absolute error (MedAE) and highest proportion of PE within ± 0.50 and ± 1.00 D compared with other formulas for the first eye. For the second-eye refinement, all three methods could reduce the second-eye MedAE. The formula-specific correction factors were 0.250, 0.331, 0.343, 0.394, 0.409, 0.452, 0.503, and 0.520 for Kane, Barrett Universal II (BUII), PEARL-DGS, Holladay 2, Holladay 1, Haigis, Hoffer Q, and SRK/T, respectively. The new AI-based Kane and PEARL-DGS with or without the CMAL methods could improve the refractive outcomes of the second eye in sequential bilateral cataract patients with long AL. The Kane, BUII, and PEARL-DGS with specific correction factors displayed higher accuracy compared with the other two methods (P \ 0.05). Conclusions: The new AI-based Kane and PEARL-DGS with or without the CMAL methods could improve the refractive outcomes of the second eye in sequential bilateral cataract patients with long AL. Notably, the Kane, PEARL-DGS, and BUII with specific correction factors displayed higher accuracy.

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“…Post-operatively, the astigmatism-correction power of toric IOLs may be reduced as a consequence of off-axis rotation [ 59 ]: a 1° rotation results in 3.3% loss of astigmatism correction, and a ≥30° rotation leads to no reduction in astigmatism magnitude but a large change in axis [ 60 ]. ELP, that is, the position of the IOL in the eye (specifically, the distance between the principal object plane of the IOL and the principal image plane of the cornea) [ 61 ] differs for each IOL design and displacement can significantly affect refraction and IOL power predictions [ 62 , 63 ]. Forward deviation of an IOL leads to myopia, and conversely backward deviation leads to hyperopia [ 62 ].…”

Section: Pre- Intra- and Post-operative Factors That Affect Refractiv...mentioning

confidence: 99%

Refractive Outcomes after Cataract Surgery

et al. 2022

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A post-operative manifest refractive error as close as possible to target is key when performing cataract surgery with intraocular lens (IOL) implantation, given that residual astigmatism and refractive errors negatively impact patients’ vision and satisfaction. This review explores refractive outcomes prior to modern biometry; advances in biometry and its impact on patients’ vision and refractive outcomes after cataract surgery; key factors that affect prediction accuracy; and residual refractive errors and the impact on visual outcomes. There are numerous pre-, intra-, and post-operative factors that can influence refractive outcomes after cataract surgery, leaving surgeons with a small “error budget” (i.e., the source and sum of all influencing factors). To mitigate these factors, precise measurement and correct application of ocular biometric data are required. With advances in optical biometry, prediction of patient post-operative refractory status has become more accurate, leading to an increased proportion of patients achieving their target refraction. Alongside improvements in biometry, advancements in microsurgical techniques, new IOL technologies, and enhancements to IOL power calculations have also positively impacted patients’ refractory status after cataract surgery.

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Determining the Theoretical Effective Lens Position of Thick Intraocular Lenses for Machine Learning–Based IOL Power Calculation and Simulation

Abstract: Determining the theoretical effective lens position of thick intraocular lenses for machine learning-based IOL power calculation and simulation.

Cited by 27 publications

References 37 publications

Theoretical Relationship Among Effective Lens Position, Predicted Refraction, and Corneal and Intraocular Lens Power in a Pseudophakic Eye Model

Theoretical Relationship Among Effective Lens Position, Predicted Refraction, and Corneal and Intraocular Lens Power in a Pseudophakic Eye Model

Comparison of Formula-Specific Factors and Artificial Intelligence Formulas with Axial Length Adjustments in Bilateral Cataract Patients with Long Axial Length

Refractive Outcomes after Cataract Surgery

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