Background/aims To compare the accuracy of 13 formulas for intraocular lens (IOL) power calculation in cataract surgery.
Methods In this retrospective interventional case series, optical biometry measurements were entered into these formulas: Barrett Universal II (BUII) with and without anterior chamber depth (ACD) as a predictor, EVO 2.0 with and without ACD as a predictor, Haigis, Hoffer Q, Holladay 1, Holladay 2AL, Kane, Næser 2, Pearl-DGS, RBF 2.0, SRK/T, T2 and VRF. The mean prediction error (PE), median absolute error (MedAE), mean absolute error and percentage of eyes with a PE within ±0.25, ±0.50, ±0.75 and ±1.00 diopters (D) were calculated.
Results Two hundred consecutive eyes were enrolled. With all formulas, the mean PE was zero. The BUII with no ACD had the lowest standard deviation (±0.343 D), followed by the T2 (0.347 D), Kane (0.348 D), EVO 2.0 with no ACD (0.348 D) and BUII with ACD (0.353 D) formulas. The difference among the MedAEs of all formulas was statistically significant (p<0.0001); the lowest values were achieved with the Kane (0.214 D), RBF 2.0 (0.215 D), BUII with and without ACD (0.218 D) and SRK/T (0.223 D). A percentage ranging from 80% to 88.5% of eyes showed a PE within ±0.50 D and all formulas achieved more than 50% of eyes with a PE within ±0.25 D.
Conclusion All investigated formulas achieved good results; there was a tendency towards better outcomes with newer formulas. Traditional formulas can still be considered an accurate option.
- lens and zonules
- optics and refraction
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Contributors GS: concept and design, data acquisition, data analysis, drafting manuscript, statistical analysis and final approval. MDM: concept and design, data acquisition, data analysis, drafting manuscript, statistical analysis and final approval. KJH: concept and design, data analysis, drafting manuscript, clinical revision of the manuscript, supervision and final approval. KN: concept and design, drafting manuscript, clinical revision of the manuscript, supervision and final approval. DS-L: concept and design, data analysis, drafting manuscript, clinical revision of the manuscript, securing funding and final approval. AV: concept and design, data acquisition, clinical revision of the manuscript and final approval. LDC: concept and design, data acquisition, clinical revision of the manuscript and final approval. CET: concept and design, drafting manuscript, clinical revision of the manuscript, supervision and final approval.
Funding The contribution of IRCCS - G.B. Bietti Foundation was supported by the Italian Ministry of Health and Fondazione Roma.
Competing interests KJH licenses the registered trademark name Hoffer to ensure accurate programming of his formulas to Carl Zeiss-Meditec (IOLMasters), Haag-Streit (LenStar/EyeStar), Heidelberg Engineering (Anterion), Oculus (Pentacam AXL), Movu (Argos), Nidek (AL-Scan), Tomey (OA-2000), Topcon EU/VisiaImaging (Aladdin), Ziemer (Galilei G6) (except Alcon (Verion)) and all A-scan biometer manufacturers. Dr Savini is a consultant to CSO, and has received speaker honoraria from Alcon, Oculus and Zeiss.The remaining authors have no financial interests.
Patient consent for publication Not required.
Ethics approval The study protocol was approved by the local ethics committee and the study complied with the tenets of the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. Deidentified participants' data (biometric measurements, implanted IOL power, postoperative refraction, prediction error by each formula) are available from Giacomo Savini, MD (firstname.lastname@example.org).