Prospective Evaluation of a New IOL Power Formula in Eyes Measured By Sum-of-Segments Biometry

Area of Science:

• Ophthalmology
• Biometry
• Surgical Outcomes

Background:

• Cataract surgery relies on accurate biometry for predictable refractive outcomes.
• Existing formulas like Barrett Universal II (BUII-SOS) have limitations, particularly in certain axial lengths.
• Advancements in biometry, such as sum-of-segments (SOS) measurements, offer potential for improved accuracy.

Purpose of the Study:

• To evaluate clinical outcomes using the Barrett True Axial Length with sum-of-segments (BTAL-SOS) biometry.
• To compare the refractive predictability of BTAL-SOS against the Barrett Universal II with sum-of-segments (BUII-SOS) formula.
• To identify specific axial length ranges where BTAL-SOS may offer superior performance.

Main Methods:

• A prospective, multi-site, multi-surgeon study involving 523 eyes undergoing cataract surgery.
• Calculation of expected residual refractions using both BTAL-SOS and BUII-SOS formulas.
• Analysis of prediction error and accuracy (≤0.50 D) across various axial length categories.

Main Results:

• Overall, BTAL-SOS and BUII-SOS showed comparable mean prediction errors (MPE) (0.00±0.27 D vs 0.00±0.28 D, p=0.06).
• BTAL-SOS demonstrated statistically superior performance in eyes shorter than 22.50 mm (MPE -0.05±0.31 D vs 0.07±0.36 D, p=0.03).
• BTAL-SOS achieved higher prediction error rates ≤0.50 D in short eyes (96.0% vs 84%) and medium-short eyes (87.5% vs 81.25%).

Conclusions:

• The BTAL-SOS formula offers statistically significant improvement over BUII-SOS for eyes shorter than 22.50 mm.
• BTAL-SOS shows high accuracy across all axial lengths, with particular benefit in shorter eyes.
• This study supports the use of BTAL-SOS for enhanced refractive predictability in cataract surgery.