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. 2022 Nov 1;48(11):1305-1311.
doi: 10.1097/j.jcrs.0000000000000983. Epub 2022 Jun 1.

Preliminary demonstration of a novel intraocular lens power calculation: the O formula

So Goto  1 , Naoyuki Maeda, Kazuhiko Ohnuma, Tjundewo Lawu, Ryo Kawasaki, Shizuka Koh, Kohji Nishida, Toru Noda
Affiliations

Preliminary demonstration of a novel intraocular lens power calculation: the O formula

So Goto et al. J Cataract Refract Surg. .

Abstract

Purpose: To evaluate the performance of a new formula of intraocular lens (IOL) power calculation (the O formula) based on ray tracing without commonly used parameters, including ultrasound-compatible axial length, keratometry readings, and A-constant.

Setting: Tokyo Medical Center, Tokyo, Japan.

Design: Retrospective consecutive case series.

Methods: 423 eyes (423 patients) implanted with a single-piece, L-loop, acrylic IOL were enrolled. All biometric data for the O formula were obtained by anterior segment swept-source optical coherence tomography (SS-OCT) and SS-OCT-based biometer. The performance of the O formula was compared with those of the Barrett Universal II (BUII) and Kane formulas at 1 month postoperatively. Statistical analysis was applied according to a heteroscedastic test with SD of prediction errors as the main parameter for formula performance.

Results: The SD of the O formula (0.426) was statistically significantly lower than that of the BUII formula (0.464, P = .034) but not statistically significantly different from that of the Kane formula (0.433, P = .601). The percentages of patients with refractive prediction errors within ±0.50 diopter (D) and ±1.00 D of the O, BUII, and Kane formulas were 75.4% and 98.6%, 77.1% and 97.9%, and 76.6% and 98.1%, respectively.

Conclusions: The O formula, based on ray tracing using SS-OCT-based devices, is one of the promising approaches for IOL power calculation, although additional larger scale studies are needed. It may be used as an alternative in IOL power calculation because of its independence from commonly used parameters.

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Conflict of interest statement

Disclosures: N. Maeda has received lecture fees from Tomey Corp. for sponsored seminars unrelated to this article. The coauthors of this article report no additional potential conflicts of interest.

Figures

Figure 1.
Figure 1.
A horizontal cross-sectional image by anterior segment swept-source optical coherence tomography before (a) and after (b) cataract surgery. AQD = aqueous depth; AR = angle recess; ATA depth = angle-to-angle depth; CCT = central corneal thickness; LE depth = lens equator depth; Lens-f = lens fornix; LT = crystalline lens thickness; SS = scleral spur
Figure 2.
Figure 2.
Scatterplot of the correlation between postoperative IOL depth and predicted IOL depth (n = 423).
Figure 3.
Figure 3.
Scatterplot with 3 classes of absolute refractive error (RE) calculated using the Barrett Universal II formula (a), Kane formula (b), and O formula (c) in relation to axial length and the average keratometry value obtained by swept-source optical coherence tomography–based biometer. Absolute REs were color-coded into 3 classes: red dot, more than 1.0 D; green dot, 0.5 D or more and 1.0 D or less; and blue dot, less than 0.5 D.
See this image and copyright information in PMC

References

    1. Koch DD, Hill W, Abulafia A, Wang L. Pursuing perfection in intraocular lens calculations: I. Logical approach for classifying IOL calculation formulas. J Cataract Refract Surg 2017;43:717–718 - PubMed
    1. Cooke DL, Cooke TL. Comparison of 9 intraocular lens power calculation formulas. J Cataract Refract Surg 2016;42:1157–1164 - PubMed
    1. Kane JX, Van Heerden A, Atik A, Petsoglou C. Intraocular lens power formula accuracy: comparison of 7 formulas. J Cataract Refract Surg 2016;42:1490–1500 - PubMed
    1. Melles RB, Holladay JT, Chang WJ. Accuracy of intraocular lens calculation formulas. Ophthalmology 2018;125:169–178 - PubMed
    1. Darcy K, Gunn D, Tavassoli S, Sparrow J, Kane J. Assessment of the accuracy of new and updated IOL power calculation formulas in 10930 eyes from the UK National Health Service. J Cataract Refract Surg 2020;46:2–7 - PubMed