EyeWorld Asia-Pacific March 2013 Issue

43 EWAP REFRACTIVE March 2013 In fact, while standard LASIK patients experience a “wow” factor almost immediately post- op, that effect tends to diminish with regression over the course of weeks and months in high myopes. With Lasik Xtra, it’s just the opposite, Dr. Tan said. A small amount of myopia tends to remain immediately post-op, and vision continues to improve to plano until about the three-month follow-up period, he said. “The patients tell me they see better and better,” Dr. Tan said. “So I am getting late-onset ‘wows.’” Dr. Tan much prefers late- onset “wows” to regression, and so do his patients, he said. Patients potentially at risk for ectasia (i.e., young patients, those with thinner corneas, etc.) also appreciate the added potential safety that crosslinking allows. In my hands Normally, corneal ectasia develops anywhere from two to four years after LASIK and even as late as 10 years post-op, Dr. Tan said. “This is something very difficult to predict in normal eyes,” Dr. Tan said. “So I do [Lasik Xtra] on all high myopes, and all patients who have a residual corneal thickness of 250-300 microns in the stromal bed underneath the flap. I tell the patient, ‘I think you need Lasik Xtra just in case I make the cornea too weak.’ Most of them say, ‘If it’s no risk to me, I just get a bit of insurance.’” As noted earlier, Dr. Tan also performs Lasik Xtra on hyperopes. Normally, Dr. Tan starts out the LASIK procedure with IntraLase (Abbott Medical Optics, Santa Ana, Calif., USA). He makes a 100- to 110-micron flap. Dr. Tan applies the riboflavin (without dextran) for 45 seconds to the stroma, rinsing any excess from the flap. Then he puts the flap back. Dr. Tan applies UV light (30 mW/cm2) to the cornea for 45 seconds. Afterward, he waits an additional minute. That’s it. These are the only procedural differences compared to standard LASIK. For Dr. Tan, this means no additional time to the LASIK procedure required. Normally when Dr. Tan doesn’t perform Lasik Xtra, after putting the flap back, he waits three minutes and then finishes the procedure. “I like to wait three minutes for my flap to really stick on well so there are no flap shifts [during standard LASIK],” Dr. Tan said. “I used to wait one minute but then would occasionally get a few flap shifts. Then I waited two minutes and rarely would get flap shifts. When I wait three minutes I get no flap shifts. For the last few thousand cases I have never had a flap shift. So I wait three minutes. It seems to be a nice magic figure for me.” Now instead of waiting three minutes, he performs the crosslinking component during this time. With the riboflavin component, UVA illumination component, and added machines moving about during crosslinking, the time involved is identical to Dr. Tan’s standard LASIK procedure. “It doesn’t increase my time for surgery at all, at least for my technique,” Dr. Tan said. Drawbacks vs. drawbacks Initially, Dr. Tan said he was standard LASIK with the MEL 80 excimer laser (Carl Zeiss Meditec) with no eyes losing more than one line CDVA. Mean post-op mesopic contrast sensitivity was either the same or slightly better than pre-op at 3, 6, 12, and 18 cpd for all three populations, using the CSV-1000. In summary, Presbyond Laser Blended Vision is a solution for presbyopia that meets all the goals of good binocular vision at all distances, no compromise in safety, contrast sensitivity, or night vision, and retention of functional stereo acuity. The procedure is immediately reversible by wearing spectacles, or a simple retreatment can be done using a standard excimer laser ablation with the advantage of keeping the depth of field. All this is achieved while simultaneously correcting a wide range of refractive errors and astigmatism levels. he key to this approach was to base it on the natural mechanisms of spherical aberration processing and binocular fusion, unlike multifocal approaches that require the patient to adjust to the unnatural situation of having to differentiate between two images in the same eye. EWAP Editors’ note: Dr. Reinstein practices at the London Vision Clinic, London, England, UK, and is affiliated with the Department of Ophthalmology, Columbia University Medical College, New York, NY, USA, and the Centre Hospitalier National d’Ophtalmologie, Paris, France. He has financial interests with Carl Zeiss Meditec and ArcScan Inc. (Morrison, Colo., USA). Contact information Reinstein: +44 020 7224 1005, dzr@londonvisionclinic.com Presbyond - from page 37 Strengthening - from page 40 using a riboflavin formula that included dextran during the Lasik Xtra procedure. “When you leave dextran underneath the flap, it causes a little bit of DLK,” Dr. Tan said. “With the new formulation of riboflavin without dextran—with just normal saline—there is no DLK.” The DLK experienced previously was mild, grade 1 DLK, he said. While the jury is still out on the long-term effects of crosslinking, Dr. Tan is convinced that it is safer than performing PRK with mitomycin-C, another refractive surgery option for higher myopia that reduces the risk of ectasia. “If you have a choice between crosslinking and mitomycin-C, mitomycin-C is more dangerous,” he said. Meanwhile, Lasik Xtra is a better option than the Visian ICL (STAAR Surgical, Monrovia, Calif., USA) for many cases in Singapore, he said. Dr. Tan described the typical Singaporean myope as having “long eyeballs and anterior chambers that are too shallow for the Visian ICL. If I try to [implant a Visian ICL] in Singapore, the anterior chamber is going to be too small.” Referring to Lasik Xtra, Dr. Tan said, “If there is no downside, why not do it?” EWAP Editors’ note: Dr. Tan has no financial interests related to this article. Contact information Tan: +65 6738 8122, jtaneyes@singnet.com.sg