JCRS highlights chosen by Professor Thomas Kohnen, European Editor, JCRS

Thomas Kohnen

Published: Tuesday, June 6, 2017

OCT VERSUS PCI BIOMETRY How do axial length measurements taken with a swept-source optical coherence tomography (SS-OCT) biometer (IOLMaster 700) and a partial coherence interferometry (PCI) biometer (IOLMaster, Version 5.4) compare? Korean researchers looked at this question in a study of 117 myopic patients. The overall axial length was greater when measured with the SS-OCT biometer than with PCI biometry. The same results were found in the sub-analysis in groups classified based on lens status, fixation status, degree of myopia, and the presence of posterior staphyloma. In eyes with good fixation, the study found statistically significant differences in axial length measurements between the two devices when posterior staphyloma was present. JY Yang et al, JCRS, “Axial length measurements: Comparison of a new swept-source optical coherence tomography-based biometer and partial coherence interferometry in myopia”; Volume 43, Issue 3, 328–332. NEW TORIC IOL CALCULATORS Newer toric calculators aim to help surgeons avoid overcorrection in eyes with with-the-rule astigmatism and undercorrection in those with against-the rule astigmatism. A new study compared several calculation approaches in 86 eyes of 86 patients undergoing toric intraocular lens (IOL) implantation. These included the original Alcon calculator and a newer version, the Holladay toric calculator, and the Barrett calculator, along with the Baylor nomogram, the Abulafia-Koch formula, and the Goggin coefficient of adjustment. The Barrett toric calculator and the new Alcon calculator yielded the lowest astigmatic prediction errors. Of the nomogram methods, application of the Abulafia-Koch formula achieved the best results. TB Ferreira et al, JCRS, “Comparison of astigmatic prediction errors associated with new calculation methods for toric intraocular lenses”; Volume 43, Issue 3, 340–347. CAPSULORHEXIS WITH IMAGED GUIDANCE Digital image guidance could be the next important step in improving the accuracy of the continuous curvilinear capsulorhexis (CCC), a study suggests. The SG3000 (formerly SMI, SensoMotoric Instruments GmbH, now VERION Image Guided System, Alcon Laboratories, Inc.) is a digital image guidance system consisting of a diagnostic reference unit and a surgery pilot for intraoperative surgical assistance. Making use of eye-tracking technology, a preoperative image is injected into the microscope and superimposed on the patient's eye. The device can be used to align toric IOLs during surgery, as well as support manual creation of a capsulorhexis with a predefined target diameter. The study looked at the capsulorhexis size of 427 eyes, 203 of which included digital image guidance. Overall, intraoperative image guidance facilitated CCC creation significantly during standard phacoemulsification. Y Haeussler-Sinangin et al, JCRS, “Clinical performance in continuous curvilinear capsulorhexis creation supported by a digital image guidance system”; Volume 43, 
Issue 3, 348–352.