Immersion Biometry for Intraocular Lens Power Calculation with Fourth-Generation Formulas

Area of Science:

• Ophthalmology
• Biomedical Engineering

Background:

• Fourth-generation intraocular lens (IOL) formulas (Barrett Universal II, Olsen, Holladay 2) are validated with optical biometry.
• Optical biometry struggles with dense cataracts, making third-generation formulas (Hoffer Q, SRK/T) with ultrasound a preferred method.
• Optical biometry's refinement with immersion ultrasound suggests fourth-generation formulas may perform well with this technique.

Purpose of the Study:

• To evaluate the precision of fourth-generation IOL power calculation formulas using immersion ultrasound measurements.
• To compare the refractive outcomes of fourth-generation formulas against third-generation formulas in eyes measured with immersion ultrasound.

Main Methods:

• Retrospective analysis of 50 eyes undergoing cataract surgery with IOL power calculated via immersion ultrasound.
• Comparison of refractive error predictions between third-generation and fourth-generation IOL formulas.

Main Results:

• No statistically significant difference in median absolute error between third-generation and fourth-generation formulas.
• Percentage of eyes within 1 D of target refraction: SRK/T (86%), Barrett II (88%), Hoffer Q (86%), Holladay 1 (84%), Holladay 2 (88%), Olsen (80%).

Conclusions:

• Fourth-generation formulas with immersion ultrasound yield comparable results to third-generation formulas.
• The refractive accuracy achieved with immersion ultrasound and fourth-generation formulas is lower than previously reported for optical biometry.