Eyeworld

EW CATARACT 24 August 2016 by Liz Hillman EyeWorld Staff Writer corrected distance visual acuity of 20/20 or better in both eyes, Ames- bury et al. found, based on the Visu- al Function (VF)-14 questionnaire, cataract surgery does benefit these patients' quality of vision. "Functional vision assessed by the VF-14 questionnaire significant- ly improved after cataract surgery in patients with 20/20 or better preoperative CDVA," Amesbury et al. wrote. "This finding suggests that loss of CDVA cannot always be used to determine who will benefit from cataract surgery." This patient, who Dr. Miller said was pretty well educated on his medical state and the options avail- able to him, knew he would need to have cataract surgery someday and it would only get worse over time. "So he thinks, why not just be done with it, knowing that in the end he might have to go through a bit of harangue to get a good result," Dr. Miller said. What makes a good result more difficult in this case than a standard cataract surgery? The previous RK, which Dr. Miller said makes the accuracy of lens power calculations difficult along with some other factors. The patient also had an un- usual number of RK incisions—19 in his right eye, 18 in his left. Dr. Miller said RK incisions usually follow in multiples of 4. Standard calculations would have told Dr. Miller to use a 19.5 D IOL. The ASCRS Post-Refractive IOL Calculator, however, suggested a higher power. Dr. Miller chose a 21.5 D lens, going even slightly more powerful than the ASCRS calculation to account for the higher number of incisions. Next, Dr. Miller had to decide where to place his phaco incision. Knowing via a Pentacam (Oculus, Arlington, Washington) image that the patient had 1.2 D of vertically oriented astigmatism and based on his RK history, Dr. Miller decided to make a scleral incision. While this allowed him to avoid crossing RK incisions, as Dr. Miller said a corneal incision might, it did cause episcleral bleeding and required cautery. With cautery comes collagen shrinkage, which causes short-term astigmatism. posterior internal corneal aberra- tions as well. The patient also had mild +1 nuclear sclerotic cataract in both eyes. After this visit, Dr. Miller told the patient that while cataract surgery would probably improve his vision, he could most certainly wait longer. Within the month, the patient was back, opting for cataract surgery in his right eye. "He's a bit of a perfectionist," Dr. Miller said. And he's not alone. "Patients who are willing to allow their eyes to be cut generally have a low threshold for complain- ing about things. You see that with the current LASIK patients," Dr. Miller said. In fact, a study published in 2015 in the Journal of Cataract & Refractive Surgery found, based on data from the European Registry of Quality Outcomes for Cataract and Refractive Surgery, that patients who had corneal refractive surgery were getting cataract surgery earlier than their peers who hadn't had such a prior surgery. 1 Dr. Miller co-authored a study published in 2009 in the Journal of Cataract & Refractive Surgery that dis- cussed how some ophthalmologists might "be hesitant to operate" on a 20/20 eye, not to mention some insurance programs have visual acuity requirements to merit sur- gery. 2 Conducting a retrospective case review of patients who had Patient with 20/20 vision and only mild cataract opts for surgery now rather than later "T he acuity you measure on the eye chart is not everything," said Kevin M. Miller, MD, chief of the cataract and refrac- tive surgery division, David Geffen School of Medicine, University of California, Los Angeles. One of his recent patients is the perfect example. The 59-year-old post-RK patient who had been happy with his vision for years on his initial visit to Dr. Miller was found to be 20/20 –1 in his right eye. His manifest refraction was plano +0.5 D of cylinder. "That's almost perfect; I wish all of my patients were like that after surgery," Dr. Miller said. And yet, this man, who traveled across the country to see Dr. Miller specifically, complained of blurred vision. He said it had gradually gotten worse over the last five years, especially within the last two years. In that same visit, this patient glare tested "right off the chart" at less than 20/400, Dr. Miller said. An exam with the iTrace Ray Tracing Wavefront Aberrometer and Topographer (Tracey Technologies, Houston) revealed internal lens aberrations and, Dr. Miller thinks, "Perfectionist" RK patient presents interesting case for cataract surgery C ataract surgery on the post-refrac- tive eye poses many challenges. First, these patients, by undergoing corneal refractive surgery, have certain visual expectations. They likely expect to have "perfect" vision after cataract surgery. These expectations need to be discussed with the patient and perhaps more realistic expectations set, given the unpredictabil- ity of refractive outcomes after cataract surgery in the post-refractive eye. Second, refractive outcomes are more challenging in achieving emmetropia in these eyes, but there are now many IOL calculation algo- rithms available to help reach and achieve our target goals. Third, these patients tend to be more intolerant to decreases or changes in vision than the average patient, so may present earlier with cataract visual complaints, such as decreased acuity or contrast sensitivity, or issues with glare. This case, as presented by Cataract Editorial Board member Kevin Miller, MD, is a classic example of the post-refractive cataract patient. But it also introduces the challenges and nuances in dealing with the post-RK patient with respect to incision placement and corneal issues. As usual, Dr. Miller does a great job. Rosa Braga-Mele, MD, Cataract editor A preoperative Pentacam image revealed that the cornea was flatter in the center while the periphery was steeper. This patient also had 1.2 D of vertically oriented astigmatism. Source: Kevin Miller, MD Cataract editor's corner of the world

• Cover