EyeWorld Asia-Pacific June 2019 Issue

EWAP JUNE 2019 3 EDITORIAL T he theme of our June issue of EyeWorld ƂÈ>‡*>VˆwV is the Refractive Cataract. As expected, the issue discusses in depth the many different options available to address and improve refractive outcomes after cataract surgery and intraocular lens implantation, including addressing the presbyopic needs of patients. Options for the latter range from modest monovision to trifocals and the different types of implants are covered in detail. One of the more challenging issues that we deal with in relation to the “Refractive Cataract” is the increasing number of patients who have had previous refractive surgery and now require cataract surgery. These patients have been accustomed to good unaided vision and therefore are particularly sensitive to the issue of requiring spectacle correction following cataract surgery. Historically, the refractive outcome in patients undergoing cataract surgery after PRK, LASIK or RK has been relatively unpredictable. Attempts to improve prediction are focused on improved formulae, new technology for more precise biometry, and the ability to measure additional parameters altered by the refractive procedure. One of the formulae available for this purpose is the “True K Formula” which is available on the APACRS website (www.apacrs.org) . This formula can be used for patients who have had previous myopic, hyperopic LASIK/PRK or RK and contains an integrated algorithm to address the double K issue. More recently, swept-source OCT devices and -V…iˆ“«yÕ} ̜“œ}À>«…iÀà >Ài able to measure the posterior cornea. The altered ratio of the posterior cornea to the anterior cornea is one of the fundamental reasons for unexpected outcomes after previous refractive surgery. If this measurement is taken into account, then the prediction accuracy of formulae could potentially improve in this context. In May this year, I updated the online version of the True K toric calculator to version 2.0. This version allows the use of the actual measured posterior cornea to be utilized as an alternative to the predicted posterior cornea in calculating the required lens for patients who have undergone previous refractive surgery. In a retrospective analysis using swept-source OCT (IOLMaster 700), the predicted outcome using the True K formula with the measured posterior cornea proved to be more accurate than the outcome using standard Ks. The data was presented at the ASCRS meeting in San Diego and personally I now always take into consideration the predicted outcome using the measured posterior cornea as well as the predicted posterior cornea, with and without the history of the change in refraction associated with the refractive procedure. In addition, the “True K toric Calculator” has also been updated to version 2.0. A standard calculator is not appropriate for predicting the required toric IOL after previous refractive surgery and I developed the True K toric The Refractive Cataract V>VՏ>̜À ëiVˆwV>Þ vœÀ ̅ˆÃ purpose. With version 2.0, the True K toric calculator can also utilize the measured posterior cornea and once again this does appear to provide improved accuracy for toric IOL prediction, prediction after cataract surgery. Version 2.0 of the True K toric calculator also includes the K calculator to provide an integrated K from multiple devices. This streamlines the ܜÀŽyœÜ ˆ˜ `iÌiÀ“ˆ˜ˆ˜} LœÌ… spherical and toric outcomes in patients who have had previous refractive surgery. …œ«i Ài>`iÀà ܈ w˜` ̅i update to the True K and True K toric calculator helpful in determining the correct IOL for their patients who have undergone previous refractive surgery and of interest in this issue of the “Refractive Cataract.” EWAP Graham Barrett Chief Medical Editor EyeWorld ƂÈ>‡*>VˆwV “With version 2.0, the True K toric calculator can also utilize the measured posterior cornea and once again this does appear to provide improved accuracy for toric IOL prediction, prediction after cataract surgery. Version 2.0 of the True K toric calculator also includes the K calculator to provide an integrated K from multiple devices.” The calculator is available at www.apacrs.org.