EyeWorld India March 2013 Issue

3 EWAP March 2013 Dear Friends C ataract surgeons are now, more than ever, aware that preexisting corneal astigmatism needs to be corrected in order for patients to gain the full visual benefits of cataract surgery, especially in those having multifocal or accommodating intraocular lenses implanted. Just simply correcting the spherical refractive error without addressing the corneal astigmatism will not deliver the optimal results that our cataract patients demand today. How many of us at present, as cataract surgeons would be satisfied that an unaided vision of 6/12 or 6/9 due to residual astigmatism is considered a surgical success? I would say none. Our patients would also agree. Astigmatism has always been difficult to treat. Following presbyopia, which remains the most enigmatic and difficult refractive error to correct, astigmatism is the most difficult refractive error to treat. This is because astigmatism not only has a magnitude, it also has an axis (direction). It is a vector. In order to treat astigmatism fully, one has to not only correct the magnitude but also take into account the axis of the astigmatism. In the human eye, measurements of the magnitude and axis of astigmatismhave reached high levels of accuracy and reproducibility, but the treatment of it can be confounded by issues of visual fixation and cyclotorsion of the eye from the usual measurement position (seated) to the usual treatment position (reclined) of the patient. In this issue, we have several excellent articles on the measurement and treatment of astigmatism in cataract patients. There have been huge improvements in the way we measure astigmatism which have progressed beyond the manual keratometer to multipoint Placido, Scheimpflug and wavefront-based techniques that deliver outstanding accuracy and precision. Intraoperative methods of astigmatism correction have also progressed in leaps and bounds with limbal relaxing incisions, femtosecond laser arcuate keratotomy and toric IOLs being the preferred methods of intraoperative correction today. One article of particular significance is on the work of Douglas Koch, MD, and Li Wang, MD, on the role that posterior corneal astigmatism plays in the surgical management of astigmatism. It provides a lot of illumination on how we should think of the cornea as a structure that has not only a front surface that we can surgically manipulate, but also a posterior surface that affects the results of our treatment that we cannot manipulate as yet. To me, it does explain why sometimes we do not get the surgical outcome expected when treating low levels of corneal astigmatism in cataract patients with a toric IOL. I strongly recommend that interested colleagues read the full paper in the Journal of Cataract & Refractive Surgery referenced in the article. It will change how you use toric IOLs. It would appear that we as clinicians and surgeons view astigmatism as an always debilitating optical aberration that must be relentlessly pursued and corrected to oblivion. Is this always true? I do not think so. I feel that there is a role for small magnitudes of corneal astigmatism in the appropriate axis that might provide the eye with an IOL an increased depth of field without significant visual degradation and loss of contrast sensitivity. We all remember cases of patients with pseudoaccommodation demonstrating excellent vision for distance and near before the days of multifocal and accommodating IOLs. Perhaps we should not always view astigmatism as an evil refractive error. We could harness it to the benefit of our patients. Food for thought and after dinner conversation with our colleagues! Finally, we have several comments from our Asia-Pacific surgeons on some of these articles. This gives a very special and unique perspective that is the hallmark of our publication and I am sure readers will find this edition informative and beneficial to their clinical practice. I wish all of our readers and supporters the very best for 2013. Warmest regards Chan Wing Kwong, MD Guest Medical Editor and Editorial Board Member, EyeWorld Asia-Pacific Letters from the Editors Dear Friends I t gives me immense pleasure to introduce the current issue of EyeWorld Asia-Pacific . Achieving emmetropia in astigmatic cataract patients has been the goal of most cataract surgeons for the past few decades. This issue includes interesting discussions on the use of femtosecond lasers for increasing the precision of astigmatic incisions. With better understanding of post-surgery residual astigmatism after astigmatic incisions as well as toric intraocular lenses, experts stress the importance of posterior corneal curvature. Experts share their results achieved after accounting for back corneal curvature when selecting toric intraocular lenses. In the Cornea section, DSEAK and DMEK are discussed as options for endothelial keratoplasty. DMEK eliminates the stromal carrier used in DSAEK and hence should lead to better vision. However, due to endothelial loss caused during tissue handling, DMEK remains second choice for most corneal surgeons. Meanwhile, the red flags in post-LASIK infections and presbyopic laser correction are highlighted in the Refractive Surgery section. In the Glaucoma section, a novel technique for eye drop delivery is introduced. The technique is of great advantage in being able to deliver small amounts of drug in a volume that is accurately targeted at the eye. I hope these excellent discussions make a captivating reading for you all. I would like to quote the great Tiruvalluvar from his verse 467: Action should follow analytic decision, resulting from deep deliberations: To postpone consideration until after commencing action is disgraceful. Warmest regards S. Natarajan, MD Regional Managing Editor EyeWorld Asia-Pacific EYEWORLD ASIA-PACIFIC EDITORIAL BOARD C HIEF MEDICAL EDITOR Graham BARRETT, Australia MEMBERS Abhay VASAVADA, India ANG Chong Lye, Singapore CHAN Wing Kwong, Singapore CHEE Soon Phaik, Singapore Choun-Ki JOO, Korea Hiroko BISSEN-MIYAJIMA, Japan ASIA-PACIFIC CHINA EDITION Editors-in-Chief ZHAO Jialiang ZHAO Kan Xing Deputy Editor HE Shouzhi ASIA-PACIFIC INDIA EDITION Regional Managing Editor S. NATARAJAN ASIA-PACIFIC KOREA EDITION Regional Editor-in-Chief Hungwon TCHAH Regional Managing Editor Chul Young CHOI Hungwon TCHAH, Korea John CHANG, Hong Kong Johan HATAURUK, Indonesia Kimiya SHIMIZU, Japan Pannet PANGPUTHIPONG, Thailand Prin ROJANAPONGPUN, Thailand Ronald YEOH, Singapore S. NATARAJAN, India YAO Ke, China YC LEE, Malaysia