Prospective Evaluation of a New IOL Power Formula in Eyes Measured By Sum-of-Segments Biometry
H John Shammas1, Maya C Shammas2, Sam Multack3
1From the Department of Ophthalmology (H.J.S., M.C.S.), Keck School of Medicine of USC, Los Angeles, California, USA.
Purpose:
To evaluate the clinical outcomes from cataract surgery in eyes measured with sum-of-segments (SOS) biometry using the new Barrett True Axial Length (BTAL-SOS) formula and compare the potential results with the Barrett Universal II (BUII-SOS) formula.
Design:
Prospective, multi-site, multi-surgeon, biometry accuracy study. Four private practice locations in Lynwood, CA, Encino, CA, Olympia Fields, IL, and Albuquerque, NM, USA.
Methods:
The expected residual refractions were calculated using the BTAL-SOS formula in 523 eyes after cataract surgery and compared to the potential results with the BUII-SOS formula. All eyes had a final visual acuity ≤0.20 LogMAR and ≤0.75 D of astigmatism.
Results:
Mean prediction error (MPE) for the entire series was 0.00±0.27 D with BTAL-SOS compared to 0.00±0.28 D with BUII-SOS (p = 0.06). In 79 eyes longer than 24.50 mm, MPE was - 0.02±0.24 D with BTAL-SOS vs -0.05±0.25 D with BUII-SOS (p = 0.16) and in 73 eyes shorter than 22.50 mm, BTAL-SOS statistically outperformed BU II-SOS (p = 0.03) with a MPE of -0.05±0.31 D vs 0.07±0.36 D. BTAL-SOS prediction error (PE) ≤0.50 D was 96.0% vs 84% in short eyes (AL≤22.00mm), 87.50% vs 81.25% in medium short eyes (AL>22.00mm, <22.50mm), 92.45% vs 93.26% in average eyes (AL 22.50-24.50mm), 92.68% vs 92.68% in medium long eyes (AL>24.50mm, <25.00mm) and 97.37% vs 94.74% in long eyes (AL≥25.00mm) when compared to BUII-SOS results.
Conclusion:
BTAL-SOS formula performed statistically better (p = 0.03) than BUII-SOS in eyes shorter than 22.50 mm.
