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February 2012
 

MEETING REPORTER
 

Ectasia, topography readings hot topics among military refractive surgeons


 



Reporting live from the 2012 International Military Refractive Surgery Symposium




Editors' note: This Meeting Reporter contains original reporting by the EyeWorld news team from the 2012 IMRSS in San Antonio.

 

























Early in January, military refractive surgeons convened in San Antonio for the 6th Annual International Military Refractive Surgery Symposium to exchange ideas, debate with peers, and listen to the latest research from colleagues stateside and abroad. Air Force, Army, and Navy representatives kicked off the meeting with an overview of the state of refractive surgery in each branch. The Air Force reported 84,595 refractive treatments between fiscal year (FY) 01 and December of FY 12. Ninety-four percent of patients had 20/20 vision or better 12 months out, while 32% had best corrected visual acuity (BCVA) of 20/15 or better. "No aviator has been grounded as a direct result of refractive surgery, and I think that speaks a lot to the quality of the program," said Maj. Vasudha A. Panday, M.D., San Antonio. Since 2000, the Army has reported more than 216,000 refractive procedures and has seen a shift in the types of patients being treated. "Hyperopic patients are coming back into the fold over the last year or two because of the current status of the excimer platforms," said Col. Mark F. Torres, M.D., U.S. Army Madigan Army Medical Center, Tacoma, Wash. The Army is seeing a shift back toward LASIK over surface ablation for a combination of reasons including a hyperopic patient population, femtosecond technology allowing for safer and more predictable flap creation, and speed of recovery. The Navy also described a trend toward LASIK, which accounted for 47% of the nearly 13,000 refractive procedures in FY 11. Capt. Elizabeth M. Hofmeister, M.D., head, Navy Refractive Surgery Center, San Diego, reported on a number of recent research projects, including topical cyclosporine in LASIK and photorefractive keratectomy (PRK), which examined if Restasis (Allergan, Irvine, Calif.) sped up visual recovery in normal patients. The study found no benefit of topical cyclosporine. "That is an example of good evidence-based medicine where we saved the DOD countless dollars in not using that very expensive medication for routine patients," she said. Future studies on the horizon include a head-to-head comparison of the Navy's wavefront-guided and wavefront-optimized platform. In September 2011, the Navy began enrollment in an FDA study, Patient Reported Outcomes with LASIK. Dr. Hofmeister gave an overview of her visits to all Navy Refractive Surgery Centers, highlighting some successes, tips, and challenges of the centers. "Jacksonville is one example where they have solved some of the facility issues that others of us have faced," she said. "They have a beautiful, large room that accepts all three of their lasers, and they have climate control, which has been a big issue at some of our centers." Screening and treating ectasia was a recurrent topic among speakers. William B. Trattler, M.D., refractive, corneal, and cataract specialist, Center for Excellence in Eye Care, Miami, began the ectasia conversation by pointing out the subjective nature of topography readings in his keynote address, "Advanced Diagnostics for Pre-operative Evaluation of the Refractive Surgery Candidate." "How effective are we at interpreting corneal maps?" he asked. "What it really boils down to is if a corneal map is normal or abnormal in your eyes. You're trying to screen patients and select the right candidates. You don't want to operate on someone who will develop ectasia, but you also have to be careful not to rule everyone out. Interpretation of maps is a challenge."
If a case doesn't look quite normal, he advised surgeons to thoroughly evaluate both eyes and even flip a topography reading over so the steep part of the eye is inferior. Dr. Trattler also stressed that thickness doesn't mean the cornea is strong or stiff. Although an abnormal topography is an important pre-op clue, patients with normal topographies can develop ectasia as well. "Ectasia is a risk of laser vision correction," said retired Navy Capt. Steve C. Schallhorn, M.D., former director, Cornea Service & Refractive Surgery, Naval Medical Center, San Diego; and professor of ophthalmology, University of California, San Francisco. "Sometimes there are no apparent risk factors."
Dr. Schallhorn reported his observations from a laser vision correction analysis involving 204,284 patients, 58 of whom developed ectasia. Ectasia affected more males than females, and patients were slightly younger on average than the cohort, he said. "The average age of the entire cohort was 38 years old, whereas the average age of the ectasia patient was 31," he said. "Ectasia tends to happen in younger patients, but we also have seen ectasia occur in patients over the age of 50. Older age is no guarantee [a patient is] not going to develop ectasia, but it is associated with younger patients." Dr. Schallhorn called cornea shape the "most significant risk factor" for ectasia. Anterior curvature seems to be the most predictive factor. Ectasia mostly occurred in myopes, but there were some cases of ectasia in hyperopes as well. On average, 24 months passed between treatment and ectasia diagnosis. Although determining which patients will develop ectasia can be maddening, there is good news. The final BCVA of Dr. Schallhorn's ectasia 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 ectasia, 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 surgeons 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 treatment modalities if a patient does develop ectasia. Ectasia is not something 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 correction, despite persistent rumors to the contrary. "It's still a controversial topic because people have ingrained beliefs that pupil size is very predictive of who will have quality of vision problems after surgery," he said. Simple optics suggests a relationship 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 overview of all the literature published on this topic and found one study out of 11 that reported a positive correlation between elevated pupil size and laser vision correction outcomes. "The preponderance of peer-reviewed literature shows no relationship," 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 patients. We did a data query of consecutive young myopes that underwent LASIK over a defined time period. This yielded 18,000 patients, 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 diameter of ≥8.0 mm. "Myopic patients with large low-light pupils in this large retrospective 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 uncorrected visual acuity. That's the key."



Post-LASIK corneal neuralgia

Corneal neuralgia is a newly described disease process refractive surgeons wish was mythological. Lt. Cmdr. John B. Cason, M.D., cornea, external disease, and refractive surgery, Naval Medical Center, San Diego, gave an overview of the symptoms, which many patients find excruciating. "The hallmark of this is how uncomfortable 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 feeling, however, is very real. Some patients 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 related to other chronic pain conditions 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 refractive surgeons should screen patients for underlying chronic pain syndromes as a contraindication to surgery. "There are a lot of patients we treat with refractive surgery that have done just fine," he said. "We'd be eliminating patients that could potentially have successful surgery, but it's certainly a possibility with these pre-existing syndromes that they could have this disabling condition." Dr. Cason recommended a multidisciplinary approach—for example, in conjunction with a psychiatrist—to handle these cases.



Study evaluates pain with use of different bandage contact lenses

The Acuvue Oasys is the most effective FDA-approved bandage soft contact lens following PRK to reduce pain, concluded Angelletta N. McCraney, D.O., M.P.H., during her presentation of a prospective, randomized, double-masked study. Dr. McCraney and colleagues evaluated the post-op pain level reported for eyes using the Acuvue Oasys, Ciba Air Optix, and the Bausch + Lomb (B+L) Pure Vision (Rochester, N.Y.). "Differences in post-operative pain relief have been anecdotally noted with different contact lenses," she said.
To see if this anecdotal evidence had any scientific credibility, Dr. McCraney looked at 108 eyes of 54 patients randomized to one of the three lenses. All patients were evaluated in the clinic on post-op days 1 and 4 with a survey determining absolute pain in each eye on a scale of 0-10. All patients were managed post-op with the standard post-PRK treatment regime including a topical antibiotic, topical steroid, artificial tears, and oral pain medication. For analysis of absolute pain, patients were grouped by pair of lenses used. On day 1, Acuvue eyes had the least number of more painful eyes at 7%, followed by Ciba with 30% and B+L with 56%. Seven percent reported no difference. On day 4, the Acuvue eyes had the least number of more painful eyes at 2%, followed by Ciba with 23%, and B+L with 50%. Twenty-five percent reported no difference. "The B+L lens was reported as least comfortable most often, which was statically significant," she said. "Differences in the lenses that may contribute to pain include variations in base curve diameter and oxygen permeability. The Acuvue Oasys had the lowest post-PRK pain scores. Based on this study, there is a difference in post-PRK pain based on the various contact lenses that was both statistically and clinically significant. In this study, there appears to be an association with the edge profile and the level of comfort."



Editors' note: The views and opinions given by the doctors are their own and in no way represent the U.S. government or their respective military branches. Drs. Cason, Hofmeister, McCraney, Panday, and Torres have no financial interests related to their comments. Dr. Schallhorn has financial interests with Abbott Medical Optics (Santa Ana, Calif.). Dr. Trattler has financial interests with CXL-USA and OCULUS GmbH (Wetzlar, Germany).







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