Accuracy of the Postoperative Refractive Prediction in Optical Biometry Versus Ultrasound Biometry in Preoperative Intraocular Lens Power Calculation

Background: Contact A-scan ultrasonic biometry is the most frequently utilized technique for determining axial length (AXL). Optical biometry is a technique that utilises partial coherence interferometry to determine ocular biometry parameters. The aim of this research was to compare the efficacy in estimating postoperative refraction by measuring intraocular lens (IOL) power by the optical biometry (IOL Master) and contact A-scan ultrasound plus Bausch & Lomb (B&L) keratometry after phacoemulsification surgery.

Methods: This prospective, comparative, interventional and randomized study involved 40 eyes with uneventful phacoemulsification surgery and in the bag IOL of adult patients with cataract. Subjects were allocated into 2 equal groups: group A: implanted the IOL power estimated by the automated method and group B: implanted the IOL power estimated by the manual method. All patients were subjected to complete ophthalmic examination, best-corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), snellen visual acuity, cycloplegics refraction and slit lamp examination.

Results: The mean predicted error of IOLM was -0.108 ± 0.462 (P= 0.311) in group A and was 0.053 ±1.092 (P= 0.830) in group B, and the Predicted error of A scan was -0.661 ± 0.686 (P= <0.001) in group A which is statistically significant and -0.340 ± 0.972 (P= <0.134) in group B. IOL power measured by IOLM in group A was significantly lower than IOL power measured by A-Scan (p =0.004). While the mean IOL power measured by IOLM in group B was significantly lower than IOL power measured by A-Scan (p =0.008).

Conclusions: The IOL Master accurately assesses the axial length of the lens and thus provides a significantly better prediction of IOL power and thus refractive outcome in cataract surgery than US biometry.