Impact Of Total Keratometry And Cmal In Predicting Post-Operative Spherical Equivalent In Normal Eyes
Published 2022 - 40th Congress of the ESCRS
Reference: FPM08.11 | Type: Free paper | DOI: 10.82333/wygt-h372
Authors: Sara Neto Geada Batista* 1 , Emmanuel Neves 1 , Miguel Raimundo 2 , Conceição Lobo 2 , Joaquim Murta 2
1Department of Ophthalmology, Centro Hospitalar e Universitário de Coimbra (CHUC),Coimbra,Portugal, 2Department of Ophthalmology, Centro Hospitalar e Universitário de Coimbra (CHUC),Coimbra,Portugal;University Clinic of Ophthalmology, Faculty of Medicine, University of Coimbra (FMUC),Coimbra,Portugal;Clinical Academic Center of Coimbra (CACC),Coimbra,Portugal
Purpose
Prediction accuracy of intraocular lens (IOL) calculation formulas is a major concern in cataract surgery, and precise measurements of ocular parameters are essential for optimal refractive results. Adjustments to conventional formulas and new formulas considering new parameters have been proposed, such as those incorporating total keratometry (TK) and axial length (AL) adjustment methods, namely the Cooke-modified AL (CMAL). The aim of this study was to evaluate the prediction error of conventional formulas updated with CMAL and the Barrett Universal II formula (BUII) updated with total keratometry (BUII TK).
Setting
Tertiary public hospital.
Methods
Retrospective study of consecutive patients who underwent uneventful cataract surgery with monofocal IOL implantation. The following IOL calculation formulas were applied to predict the target spherical equivalent for the implanted IOL in each subject: Holladay1, HofferQ and SRK/T with and without CMAL incorporation, BUII and BUII TK. Biometry was obtained using a swept-source optical biometer (IOLMaster 700;Carl Zeiss). Prediction errors (PE), defined as the difference between postoperative and formula-predicted SE based on the IOL power implanted, were calculated at 6-week follow-up. Mean absolute error (MeanAE), median absolute error (MedAE), and the percentage of eyes within ±0.25 diopters (D), ±0.50D and ±1.00D of PE were determined.
Results
A total of 87 eyes from 87 patients with a mean AL of 25.23±3.03 mm(range 21.24-33.78), were included. MeanAE and MedAE were slightly inferior for formulas integrating CMAL: 0.51 and 0.44 vs. 0.46 and 0.43D for SRK/T vs. SRK/T-CMAL; 0.55 and 0.45 vs 0.50 and 0.41D for Holladay1 vs. Holladay1-CMAL; 0.54 and 0.45 vs 0.48 and 0.41D for HofferQ vs. HofferQ-CMAL. The percentage of eyes within ±1.00 D of PE was slightly superior for formulas with CMAL (92.0-93.1%) vs. original AL (87.4-89.7%). Regarding the comparison of BUII and BUII TK, the percentage of eyes within ±0.50 and ±1.00D of PE was the same for both formulas (69.0% within ±0.50 and 94.3% within ±1.00D); MeanAE and MedAE were also similar (BUII 0.40 and 0.32D, BUII TK 0.40 and 0.34D).
Conclusions
The CMAL adjustment improved classical formulas prediction performance. Meanwhile, prediction accuracy of the BUII TK formula using total keratometry was not superior to conventional BUII using simulated keratometry from anterior measurements.