ESCRS HIGHLIGHTS

NEW TORIC IOL CALCULATOR Researchers have reported promising results with a new regression formula (Abulafia-Koch) which was developed to calculate the estimated total corneal astigmatism based on standard keratometry measurements. The error in the predicted residual astigmatism was calculated by the Alcon and Holladay toric intraocular lens (IOL) calculators, with and without adjustments by the Abulafia-Koch formula. A retrospective study of 78 eyes compared the new and old formulae. The Alcon and the Holladay toric calculators had a higher proportion of eyes within ±0.50D of the predicted residual astigmatism with the Abulafia-Koch formula than without it. There were no significant differences between the results of the Abulafia-Koch-modified Alcon and the Holladay toric calculators and those of the Barrett toric calculator. A Abulafia et al, JCRS, “New regression formula for toric intraocular lens calculations”, Volume 42, Issue 5, 663–671. OPTICAL BIOMETRY A new optical biometer (AL-Scan) produced highly comparable measurements to those obtained with standard Scheimpflug anterior segment tomography, report researchers. They conducted a prospective randomised study comparing mean central corneal thickness (CCT), anterior chamber depth (ACD), and keratometry measurements in 121 healthy patients. The mean difference in CCT was 1.61μm. The mean difference in the aqueous depth and ACD was 0.02mm. For the 2.4mm K readings from the new biometer versus the standard K readings from the Scheimpflug tomographer, the mean difference for flat K, steep K and mean K was 0.10D, 0.05D, and 0.08D, respectively. C McAlinden et al, JCRS, “Agreement of anterior ocular biometric measurements with a new optical biometer and a Scheimpflug tomographer”, Volume 42, Issue 5, 679–684. NEW IMAGE-GUIDED SYSTEM A recent study confirms the repeatability and comparability of a new image-guided system which provides K and axis measurements that can be used for surgical planning of IOL implantation. The study compared the VERION™ Image Guided System (Alcon) versus partial coherence interferometry (PCI), Scheimpflug imaging, and optical low-coherence reflectometry (OLCR) devices. The image-guided system's corneal radii measurements were not significantly different from those of the OLCR device. Small, significant differences were found between the image-guided system and the PCI system; and moderate, significant differences were found between the image-guided system and the Scheimpflug device. The position of the steep axes did not differ significantly between the image-guided system and the other devices. A Mueller et al, JCRS, “Comparison of a new image-guided system versus partial coherence interferometry, Scheimpflug imaging, and optical low-coherence reflectometry devices: Keratometry and repeatability”, Volume 42, 
Issue 5, 672–678.