Comparison of 2 laser instruments for measuring axial length

Area of Science:

• Ophthalmology
• Biomedical Optics
• Optical Engineering

Background:

• Accurate biometry is crucial for intraocular lens (IOL) power calculation.
• Laser biometry devices offer non-contact measurement of ocular parameters.

Purpose of the Study:

• To compare axial length (AL), anterior chamber depth (ACD), and keratometric (K) measurements between two laser biometers.
• To evaluate the impact of these measurements on IOL power prediction error.

Main Methods:

• Prospective comparative observational study in private practices.
• Measurements performed using an IOLMaster (partial coherence interferometry - PCI) and a Lenstar LS 900 (optical low-coherence reflectometry - OLCR).
• IOL power calculated using the Haigis formula; prediction error analyzed.

Main Results:

• High correlation between AL, ACD, and K measurements from both devices in cataract and clear lens eyes.
• Statistically significant differences observed in AL, ACD, and K measurements between OLCR and PCI devices (P<.0001).
• Mean absolute error in IOL power prediction was comparable between the two devices (0.455 D for OLCR vs. 0.461 D for PCI, P>.1).

Conclusions:

• Laser biometry devices utilizing OLCR and PCI provide comparable measurements for key ocular parameters.
• A minor adjustment to the a(0) constant in the Haigis formula is suggested for OLCR device use.
• Both devices demonstrate similar accuracy in IOL power prediction.