EyeWorld India March 2017 Issue

3 EWAP March 2017 Letters from the Editors Dear Friends I am very happy to present this issue of EyeWorld Asia-Pacific, which is as usual filled with rich scientific knowledge. This issue features cataract surgery related issues such as IOL power calculation, postoperative glaucoma management, lens extraction in PACG, benefits of trifocal IOLs, and more. This issue also talks about collagen cross linking in thin cornea and refractive surgeries. In the article, “Perfecting IOL power predictions”, Liz Hillman discusses tips about how an ophthalmologist can improve the accuracy of his or her IOL calculation. Experts provide their thoughts on how to get as close to target as possible, the goal being a target refraction of ±0.5 D. Ellen Stodola talks about the impact of previous refractive surgery on IOL power choice. Past history of eye operations (such as refractive surgery, cataract surgery, and retinal surgery) has an impact on the IOL power calculation. In an in-depth article, EyeWorld Contributing Writer Vanessa Caceres discusses how advanced technology can improve astigmatic outcomes after cataract surgery. Though many tips are given to maximize technology use, the writer warns that a backup plan in case of technology failure is also important. Rich Daly writes on important tips for selecting the best keratometry values for IOLs. These tips are important for improving the choice of keratometry values when determining IOL calculations and astigmatism management because most devices do not yield identical keratometry values. In another article, Liz Hillman discusses the management of glaucoma medicines after cataract surgery. After cataract surgery, many ophthalmologists use prostaglandin analogs with steroids in glaucoma patients. The important point is to balance probable risks while controlling IOP within safe limits. In another article related to glaucoma patients, experts discuss how ocular surface disease should be considered when choosing a treatment plan in glaucoma patients. Written by Ellen Stodola, this article is an excellent piece of information regarding treatment of ocular surface problems in this condition. Apart from these knowledge-packed articles, this issue of EyeWorld Asia- Pacific also contains many other thought-provoking articles. For example, in the article “Five refractive surgery mistakes no surgeon should make”, Stefanie Petrou Binder describes the most common and potentially damaging errors in refractive surgery. By avoiding these mistakes, patient’s visual outcomes can be significantly improved. In summary, this issue contains immense knowledge for eye care professionals. This information when translated into the wisdom of patient care will improve the science of eye care. We should always be open to new knowledge and apply it wisely. As quoted in Chapter Ninety-Five of the Thirukkural , Diagnose the illness, trace its cause, Seek the proper remedy and apply it with skill. — TirukkuraL , Verse 948 in chapter ‘95’ (Medicine) Warmest Regards, S. Natarajan, MD Regional Managing Editor EyeWorld Asia-Pacific Dear Friends P erfect IOLprediction is thedreamof every eye surgeon and the theme for our current issue of EyeWorld Asia-Pacific . The goal remains elusive but has become increasingly important as complications in cataract surgery have become infrequent and patients’ expectations include freedom from spectacles following surgery. The field of biometry began in the 1880s with the development of the first practical keratometer by Emile Javal. This enabled accurate measurements of the anterior corneal surface and assisted Gullstrand and Tschernig to describe the optics of the human eye. Keratometry together with refraction is sufficient to predict the required intraocular lens power by vergence formulae for an aphakic eye which was the expected state following cataract surgery until Ridley changed the world with the first intraocular lens implantation in 1949. Thepostop refractionafter Ridley’sfirst IOL implantationwas –24.00/6.00 x 30° as the higher index of refraction of polymethylmethacrylate had not been fully accounted for in designing the first intraocular lens. There was no reliable method of measuring axial length in the following decades and the first IOL formula was simply a standard IOL power of ~19.5 D multiplied by the patient’s refraction. Reliable ultrasound machines able to measure axial length became available in the 1970s due to the efforts of pioneers like Karl Ossoinig and Jackson Coleman. Although immersion ultrasound measurements are more reliable, contact A Scan measurements are more easily obtained and became predominant. Inadvertent compression of the cornea was problematic and the prediction accuracy improved dramatically with the introduction of partial coherence interferometry developed by Adolf Fercher with the first IOLMaster in 2000. Errors in axial length measurements were no longer responsible for the majority of unexpected errors and prediction of the effective lens position (ELP) became the limiting factor in most circumstances. Improved formulae became available and modern formulae use additional parameters such as lens thickness available with optical biometers based on optical low coherence reflectometry. More recently, swept-source OCT technology has been introduced. This will allow us to measure the posterior cornea more accurately, which should be most helpful in post-LASIK patients requiring cataract surgery as well as toric calculations. Even spherical equivalent prediction can be enhanced with this technology once fully implemented and integrated with modern formulae. In this issue, experts provide their own perspective and suggestions to enhance IOL power prediction and I hope this brief history of modern biometry provides a useful perspective in how much has been achieved as we strive for perfect IOL prediction. Warmest regards Graham Barrett Chief Medical Editorial EyeWorld Asia-Pacific