EyeWorld Asia-Pacific March 2021 Issue

among the formulas with TK, Barrett True K TK, EVO TK, and Haigis TK formulas performed the best. Dr. Yeo concluded, “The IOL- Master 700 is really opening up a new dimension with new measurements to improve our outcomes. Measuring the posterior corneal radius enables us to more accurately predict IOL power for post-refractive surgery patients.” when using the Barrett True K with TK compared to the Shammas, Haigis-L, and ASCRS Average formulas. In fact, the highest number of eyes that came within 0.5 D utilized the Barrett True K with TK formula, indicating that using TK values may supplement outcomes when prior refraction history is not known. 7 Dr. Tun Kuan Yeo of Tan Tock Seng Hospital in Singapore also shared his thoughts in the webinar on Total Keratometry in post-refractive surgery IOL power prediction. He reit- erated the previous message that the sources of error in myopic post-re- fractive surgery patients come from mismeasuring the anterior corneal radius, ignoring the posterior corneal power measurement, and predicting the ELP. Dr. Yeo also reemphasized that the IOLMaster 700 combines both the telecentric anterior corneal radius measurement, which reduces noise and improves accuracy, and swept-source OCT, providing total corneal power. Dr. Yeo conducted his own study at Tan Tock Seng Hospital and as- sessed the accuracy of different for- mulas using TK in post-myopic laser refractive surgery patients in 64 eyes from 49 patients. 8 Biometric measure- ments were taken with the IOLMas- ter 700 one month after uneventful phacoemulsification. The formulas utilized in this study included post- LASIK no-history formulas (Barrett True K, Haigis-L, Shammas-PL) and conventional formulas with TK (Barrett True K TK, EVO TK, Haigis TK, Hoffer Q TK, Holladay I TK, and SRK/T TK). The findings from the study showed that without TK, Barrett True K per- formed better than the Haigis-L and Shammas-PL formulas. Barrett True K TK further improved results, and Key Take Home Messages: The following points summarize the findings on IOL power calculations from various key refractive surgery leaders. 1. Measurement of the posterior cor- neal surface with the IOLMaster 700 is reliable and shall be used to further improve IOL power calculation, espe- cially when it comes to patients with previous refractive surgery. 2. When combined with TK measure- ments, formulas such as the Barrett Univ. II (TK version), EVO, and Haigis take into consideration the measured posterior corneal curvature and can improve your results. 3. Including the measured posterior corneal power with the Barrett True K formula improves IOL calculation in post refractive corneal surgery cases. References: 1. Savini G et al. Eye (Lond). 2020 Nov 2. Online ahead of print. 2. Wang L et al. J Cataract Refract Surg. 2020 Oct 16. Online ahead of print. 3. Koch DD et al. J Cataract Refract Surg. 2012 Dec;38(12):2080-7. 4. Fabian E et al. J Refract Surg . 2019 Jun 1;35(6):362-368. 5. Srivannaboon et al. Graefes Arch Clin Exp Ophthalmol . 2019 Dec;257(12):2677-2682. 6. Abulafia A et al. J Cataract Refract Surg . 2016 Mar;42(3):363-9. 7. Lawless M et al. Clin Exp Ophthal- mol. 2020 Aug;48(6):749-756. 8. Yeo et al. Eye. 2020 Aug. Open access. Figure 3. refractive prediction error when using the Barrett True K with TK compared to the Shammas, Haigis-L, and ASCRS Average formulas.] Media placement sponsored by Carl Zeiss Meditec AG Not all products, services or offers are approved or offered in every market and approved labeling and instructions may vary from one country to another. The statements of the authors of this supplement reflect only their personal opinion and experience and do not necessarily reflect the opinion of Carl Zeiss Meditec AG or any institution with whom they are affiliated. Carl Zeiss Meditec AG has not necessarily access to clinical data backing the statements of the authors.The statements made by the authors may not yet been scientifically proven and may have to be proven and/or clarified in further clinical studies. Some information presented in this supplement may only be about the current state of clinical research and may not be part of the official product labeling and approved indications of the product.The authors alone are responsible for the content of this supplement and any potential resulting infringements resulting from, in particular, but not alone, copyright, trademark or other intellectual property right infringements as well as unfair competition claims. Carl Zeiss Meditec AG does not accept any responsibility or liability of its content.