EyeWorld Asia-Pacific December 2011 Issue

26 EW CATARACT/IOL December 2011 Expectations, IOL calculations, are two problem areas I t’s a growing patient demographic—patients with previous refractive surgery who now come to your office for cataract surgery. “We often see patients who had LASIK or PRK 10 years ago when they were in their early 50s. Now they’re in their early 60s and they think they need an enhancement,” said William Wiley, MD, Brecksville, Ohio, USA. “It’s not the LASIK that’s changed, it’s that they need cataract surgery.” Managing these patients can be more challenging than other patient groups. First, these patients tend to have higher expectations, said Li Wang, MD, research associate, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, USA. “I think the key is managing patients’ expectations,” said Harry H. Huang, MD, Bethesda, Md., USA. He goes out of his way to emphasize that cataract post-op vision will not be as perfect as it may have been after the patient’s initial refractive surgery. He will also tell patients that some surgeons believe there is a 20% chance that they will need a lens exchange—although his personal experience with lens exchange is not that high, he wants the patient to understand what might occur post-op. He will refer difficult anatomical cases to a like-minded local colleague for a second opinion. If he senses a patient has a more difficult personality, he will often delay surgery or not perform it at all. Surprisingly, although this patient group generally has high hopes, a number of post-RK patients have suffered through poor vision and are often happy with the results that cataract surgery can give, said Douglas D. Koch, MD, professor of ophthalmology, the Allen, Mosbacher, and Law Chair of Ophthalmology, Houston, Texas, USA. These patients may not always think to mention their previous refractive surgery early in the pre- op process, said Mark H. Blecher, MD, Philadelphia, Pa., USA. “I do a lot of combination cases with our retina department,” he said. “Occasionally, I do the surgery but don’t get to talk to the patient much before. Then the patient will tell me in passing that he or she had LASIK. That can throw a monkey wrench into things.” This is why it’s crucial that staff members and pre-op forms ask about previous refractive surgery, Refractive patients pose challenges during cataract surgery by Vanessa Caceres EyeWorld Contributing Editor Views from Asia-Pacific Ronald YEOH, FRCS, FRCOphth, DO, FAMS Senior Consultant, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 Consultant Eye Surgeon & Medical Director, Eye & Retina Surgeons, #13-03 Camden Medical Centre, 1 Orchard Boulevard, Singapore 248649 Tel. no. +6567382000 Fax no. +6567382111 snecyls@snec.com.sg I ncreasing numbers of post-LASIK patients are coming up for cataract surgery and these patients often have higher expectations of precise refractive outcomes after cataract surgery, based on their refractive surgery experience. However, the difficulty in achieving accurate measurement of true corneal K values after LASIK is well recognized. This article summarizes the available options very well. When LASIK-related data is unavailable, the Haigis-L formula has worked reliably for many of us. When the amount of correction and post-LASIK refraction information is available, the ASCRS post-refractive IOL calculator is certainly very useful. There is however another very simple to use and accurate method published by Graham Barrett 1 and available on the APACRS website (http://www.apacrs.org/) under the heading Biometry Calculation Post-Refractive Surgery. This very easy to use calculator generates True-K values which can then be used in conjunction with various formulas, e.g., Universal, SRK/T, and Holladay. I have found that the Barrett True-K Formula V10 has yielded excellent results after implant surgery. As an added benefit, this Barrett True-K formula also gives more accurate outcomes when used for extremely myopic eyes where negatively powered implants are used. Just enter 0 for pre-LASIK refraction and 0 for post-LASIK refraction apart from the axial length, K value and A constant and an accurate True-K IOL power will be generated. The more methods we have at our disposal for accurate biometry in these “tricky” eyes, the better we can corroborate the information we have so that better refractive outcomes result. Reference 1. Barrett GD. An improved universal theoretical formula for intraocular lens power prediction. J Cataract Refract Surg . 1993 Nov;19(6):713-20. Editors’ note: Dr. Yeoh has no financial interests related to his comments. AT A GLANCE • Cataract patients who have previously had refractive surgery often have higher expectations for surgical outcomes • A number of IOL calculation tools, including the ASCRS post-refractive surgery IOL calculator, can help surgeons pinpoint the best IOL for patients. Newer devices like the ORange aberrometer allow surgeons to take intraoperative refractive measurements • Patients with previous RK present even more of a challenge to cataract surgeons because of factors such as hyperopic drift • Managing expectations before surgery can help keep patients prepared for the occasional refractive surprise Dr. Blecher said. While surgeons commonly try to track down pre-op refraction data, this can be hard to obtain if the patient had surgery outside of the US or if the doctor has retired. Other times, the challenge comes in tracking down when the patient had surgery and what procedure was performed. “With earlier generation PRK, the optical zones were smaller, and those patients have flatter true keratometry and a greater chance of refractive