Phacoemulsification, capsulorhexis, and intraocular lens power prediction accuracy

Area of Science:

• Ophthalmology
• Surgical Outcomes
• Biomedical Engineering

Background:

• Phacoemulsification with capsulorhexis enhances surgical consistency.
• Predictable refractive outcomes are crucial for successful intraocular lens (IOL) implantation.
• Current IOL power prediction formulas aim to minimize refractive surprises post-surgery.

Purpose of the Study:

• To evaluate the refractive prediction accuracy of contemporary IOL power formulas.
• To compare the performance of Binkhorst II, SRK/T, and Olsen formulas in phacoemulsification cases.
• To investigate the impact of axial length and anterior chamber depth (ACD) on refractive prediction error.

Main Methods:

• Retrospective review of 628 phacoemulsification cases, including short (<22 mm) and long (>25 mm) eyes.
• Analysis of refractive prediction errors using Binkhorst II, SRK/T, and Olsen formulas.
• Evaluation of manufacturer-recommended versus optimized anterior chamber depth (ACD) values.

Main Results:

• The Binkhorst II formula with manufacturer ACD values yielded a mean absolute refractive error of 0.56 D.
• Optimizing ACD values reduced the Binkhorst II error to 0.51 D.
• The Olsen formula achieved the lowest mean error (0.47 D), followed by SRK/T (0.51 D), with both showing no significant bias related to axial length (P < .01).

Conclusions:

• The Olsen and SRK/T formulas offer superior refractive prediction accuracy compared to the Binkhorst II formula.
• The observed high prediction accuracy may be attributed to a more predictable pseudophakic anterior chamber depth with current surgical techniques.
• Refined ACD optimization can improve the accuracy of existing IOL power calculation formulas.