FEB 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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the visual axis. In most patients, this approach is acceptable. However, in patients who have undergone previ- ous corneal surgery, such as PKP like in this patient, changes in the shape o f the cornea can give rise to diver- gent readings at different points on the cornea. 1 Corneal topographers, on the other hand, use 7,000 to 10,000 data points from the entire surface of the cornea, while centering the acquisi- tion on the corneal apex, to calcu- late curvature. Depending on the t ype of topographer being used, one can also measure the power of the posterior surface, giving a more ac- curate measure of astigmatism. 2 For instance, with the Orbscan II topog- rapher, Placido discs are reflected off the cornea and a scanning slit scans across the entire cornea and collects data from both the anterior and pos- terior surfaces of the cornea. With Scheimpflug topography, a rotating camera takes several images of the anterior segment of the eye that are then used to create a 3D model from which both anterior and posterior surface topography can be esti- mated. Therefore, corneal topogra- phy provides a more precise picture of astigmatism than biometry. Indeed, using the keratometry values from the topographer in this case provided a better outcome than if we had used the values from biometry. Conclusion Based on my experience with this case and other similar cases, I recom- mend that ophthalmologists use corneal topography rather than biometry to perform keratometry in complicated eyes that have previ- ously undergone corneal surgery or that have abnormal corneal topolo- gies. Additionally, I firmly believe that the T-flex Aspheric toric IOL is an excellent option for the treat- ment of high astigmatism, even in eyes that have had previous corneal surgery. EW References 1. Arzu Taskiran Comez and Yelda Ozkurt (2012). Surgical Correction of Astigmatism During Cataract Surgery, Astigmatism – Op- tics, Physiology and Management. Dr. Michael Goggin (Ed.), ISBN: 978-953-51-0230-4, InTech. Available from: www.intechopen.com/ books/astigmatism-optics-physiology-and- management/correction-of-astigmatism- during-cataract-surgery. 2. Bradley MJ, Coombs J, Olson RJ. Analysis of an approach to astigmatism correction during cataract surgery. Ophthalmologica. 2006;220(5):311–6. Editors' note: Dr. Muhtaseb is consultant ophthalmic surgeon at Royal Glamorgan Hospital, Cwm Taf University Health Board, Wales, U.K. Dr. Muhtaseb has financial interests w ith Rayner Intraocular Lenses. Contact information Muhtaseb: mohammed03@gmail.com EW REFRACTIVE SURGERY February 2011 49 February 2014 OPHTHALMOLOGY FUTURES FORUM TM A SIA 2014 www.ophthalmology-futures.com INCLUDING • cataract/Refractive • Retina • Glaucoma • Electronic platforms • Pharma and Drug Delivery An ophthalmologist driven forum of corporate leaders, fi nanciers, regulators and clinicians gathered to facilitate innovative ophthalmic product development and improve eye care delivery REGISTRATION OPEN 1 ST A PRIL 2014 CONRAD HOTEL, M INATO-KU, TOKYO, JAPAN CONFIRMED SPEAKERS Abhay Vasavada Adnan Tufail Al Sommer Alan Crandall Anat Loewenstein Bill Aylward Boris Malyguin Bruce Spivey Cal Roberts Christophe Baudoin Dennis Lam Donald Tan Eugene De Juan Fumio Shiraga Hungwon Tchah Ivan Goldberg Jeff Evanson John Marshall Jonathan Crowston Jorge Alio Jost Jonas Kazuno Negishi Kazuo Tsubota Keith Barton Ki Ho Park Kuldev Singh Leonard Borrmann Malvina Eydelman Michael Chiang Mingguang He Mitsuru Sawa Murthy Simbambhatla Naveed Shams Peng Khaw Quinton Oswald Ruebens Belfort Sabri Markabi Serge Resnikoff Sheng Lim Sheraz Daya Shigeru Kinoshita Soon-Phaik Chee Takeshi Sugawara Tina Wong Tom Dunlap Tony Hommer Usha Chakravarthy Venkatesh Prajna OF Ad Eye World 7.190x9.750.indd 1 29/01/2014 12:19 46-49 Refractive_EW February 2014-DL2_Layout 1 1/30/14 10:26 AM Page 49

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