Eyeworld

FEB 2012

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

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96 EW MEETING REPORTER February 2012 Meeting Reporter continued from page 95 Reporting live from the 2012 International Military Refractive Surgery Symposium final BCVA of Dr. Schallhorn's ecta- sia cases was 20/20 in 87%. "They ended up doing better than I thought," he said. "We don't have undue problems performing LASIK or PRK knowing there's a risk of infection. The risk of infection may be higher than the risk of ecta- sia, and the final BCVA of a series of microbial keratitis cases would likely be not nearly as good as this." While the threat of ectasia is very real, is it really a condition sur- geons should lose sleep over? Dr. Schallhorn doesn't believe so. "Ectasia is a risk after LASIK, but let's put it in the proper perspective of what it really means," he said. "We have excellent diagnostic tools to identify risk factors. We now have, or will soon have, good treat- ment modalities if a patient does develop ectasia. Ectasia is not some- thing we need to fear above all else." Large pupils not at greater risk The myth busting continued later on in the meeting with Dr. Schallhorn giving a talk debunking the belief that large low-light pupils are at greater risk of quality of vision symptoms after LASIK. Dr. Schallhorn found no correlation between these pupils and quality of vision or quality of life symptoms 1-month post-op laser vision correc- tion, despite persistent rumors to the contrary. "It's still a controversial topic because people have ingrained be- liefs that pupil size is very predictive of who will have quality of vision problems after surgery," he said. Simple optics suggests a rela- tionship between the large low-light pupil and visual disturbances that would particularly manifest at night, which further adds credence to this belief. There are other compensatory mechanisms, however, such as the Stiles-Crawford effect, which may mitigate against symptoms with a large pupil, said Dr. Schallhorn. Dr. Schallhorn gave an extensive Editors' note: This Meeting Reporter contains original reporting by the EyeWorld news team from the 2012 IMRSS in San Antonio. overview of all the literature pub- lished on this topic and found one study out of 11 that reported a posi- tive correlation between elevated pupil size and laser vision correction outcomes. "The preponderance of peer-re- viewed literature shows no relation- ship," he said. "But we wanted to look at this in even greater detail with the Optical Express data set. Optical Express gives a vision and well-being questionnaire to all pa- tients. We did a data query of con- secutive young myopes that underwent LASIK over a defined time period. This yielded 18,000 pa- tients, which is many times the sum of all literature." After careful analysis of sources for potential bias, Dr. Schallhorn had 2,592 patients with a pupil di- ameter of ≥8.0 mm. "Myopic patients with large low-light pupils in this large retro- spective study were not at greater risk for quality of vision symptoms or quality of life problems at 1 month post-op," he concluded. "These symptoms are most strongly influenced by the post-op uncor- rected visual acuity. That's the key." Post-LASIK corneal neuralgia Corneal neuralgia is a newly de- scribed disease process refractive surgeons wish was mythological. Lt. Cmdr. John B. Cason, M.D., cornea, external disease, and refractive sur- gery, Naval Medical Center, San Diego, gave an overview of the symptoms, which many patients find excruciating. "The hallmark of this is how un- comfortable these patients are," he said. "But when you examine them, you don't see anything causing it. These patients are extremely difficult to treat; they keep coming back to your clinic. All the therapies you give them fail, and because of this, many of us think they're making it up." The pain these patients are feel- ing, however, is very real. Some pa- tients are so uncomfortable and so despondent over failed treatments that they become suicidal. As one patient Dr. Cason had in fellowship said, "I want my eyes taken out or I want to die." Patients with corneal neuralgia will have lowered Schirmer's scores that are frequently borderline or within the normal range; they have no corneal staining, but symptoms consistent with dry eye; they have a depressed corneal sensitivity by Cochet-Bonnet esthesiometry, and a decreased nerve density by confocal microscopy. Symptoms may be re- lated to other chronic pain condi- tions such as fibromyalgia and chronic regional pain syndrome. "What exactly is this? Is it dry eye? Is it that these regenerated nerves are more sensitive?" he asked. "We're not exactly sure." Dr. Cason speculated if refrac- tive surgeons should screen patients

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