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Refractive Surgery | Jul/Aug 2009

I Chose a Wavefront Topography-Guided Ablation

A PRK enhancement several years after LASIK once again provided me with spectacle independence.

Although early in my career as an ophthalmologist I heard from various patient recollections that being awake during surgery causes anxiety, I was not able to relate to the emotional value of these statements until I decided to undergo LASIK. This was in 1998, right around the time I began my fellowship in refractive surgery at the University of British Columbia in Vancouver, Canada. Given that I would be specializing in corneal and refractive surgery—and being a contact-lens–intolerant myope—I felt that my patients had to see that refractive surgery was good enough for my own eyes.

I was extremely nearsighted; my prescription was -10.00 D in the maximum myopic meridian (-8.00 -2.00 X 180°). The disadvantages of wearing thick glasses (even high-index lenses were heavy) were numerous. Not only did I have to constantly dodge patients' inquiries as to why I was still wearing glasses when I was recommending corneal refractive surgery to them, but wearing spectacles when performing surgery through an operating microscope was less than ideal.

I asked Dan Z. Reinstein, MD, MA(Cantab), FRCSC, DABO, FRCOphth, to perform my surgery. Dr Reinstein, at the time, was also in his last month of fellowship training at the University of British Columbia. He was already an experienced LASIK surgeon, not only in routine LASIK but also in the analysis and repair of complications through his extensive and pioneering work with the Artemis VHF digital ultrasound technology (Arcscan, Inc., Golden, Colorado). I had observed some of his LASIK cases, had seen a large number of his patients postoperatively, and reviewed his outcomes (because he kept meticulous records of all his patients' visual outcomes). These factors provided a great advantage for an eye surgeon choosing an eye surgeon.

We had both the Nidek EC5000 (Nidek, Japan) and the Technolas 217C (Technolas Perfect Vision, Germany) systems available to us. We chose to do my treatment with the Techolas flying spot laser and performed my residual stromal calculations using the conventional method, substituting the Artemis-derived corneal thickness minima, which turned out to be approximately 15 µm thinner than by handheld pachymetry. (There was no wavefront- or topography-guided technology at the time.) We aimed for plano in both eyes.

Because my prescription was so high, we used a reduced optical zone size. As the moment of truth approached, I found it quite interesting how anxious I began to feel—just like a patient! I felt some anxiety during the procedure, and the Hansatome (Bausch & Lomb, Rochester, New York) suction ring was not my favorite experience, but it was over quickly. The results were fantastic. My vision was near perfect for years; however, what was a minimal undercorrection at 1 year became more symptomatic by years 2 and 3.

UNDERGOING ENHANCEMENT
After living with the stable undercorrection for a couple of years, I decided to undergo an enhancement and timed my treatment to coincide with the 2006 European Society of Cataract and Refractive Surgeons (ESCRS) meeting in London, where (the now) Professor Reinstein had established the London Vision Clinic in 2002. He used the Artemis to map my flaps and residual stromal thickness in 3D; we compared this 5-year postop map to the exam that had been performed 6 months postoperatively. Everything was stable.

We decided to perform a wavefront topography-guided treatment using the CRS-Master diagnostic system and MEL 80 laser (Carl Zeiss Meditec, Jena, Germany) to reduce my spherical aberration, which is colloquially known as expanding the optical zone, while performing a slight recentration of the original 5.5-mm ablation zone. Given the tissue constraints, I chose to have this done over the LASIK flap as a PRK. We also decided to treat only one eye, the left eye, to keep my right eye for future reading vision (ie, monovision).

The enhancement procedure was performed in front of an audience of several hundred of our colleagues attending the live surgery session during the ESCRS that afternoon. The procedure itself was much easier compared with LASIK, for many reasons. The entire procedure lasted only 5 to 7 minutes. I had my previous LASIK experience to draw from, and additionally I had now had several years experience treating patients. After surgery, I now have excellent distance vision, with an only slightly hyperopic refraction (Figure 1).

After the usual PRK recovery time, my vision started to clear nicely. Undergoing LASIK as well as PRK has benefited not only my vision but also my relationship with patients. From the first time I meet a patient and perform the initial consultation, I am able to communicate my own experience, which proves to be extremely reassuring for patients. Even though I am not presbyopic, I now have monovision, so I can discuss monovision with presbyopic patients and explain to them firsthand what to expect. For example, my binocular vision is not 100% clear, but I get about 95% for each of distance and near compared with my vision looking through each eye individually. I am, however, 100% independent from spectacles. Most of all, I can tell my patients that these procedures were safe enough for me.

Sabong Srivannaboon, MD, is an Associate Professor of Ophthalmology on the Faculty of Medicine at Siriraj Hospital, Mahidol University, Bangkok, Thailand, and practices at the TRSC International LASIK Center, Bangkok, Thailand. Dr. Srivannaboon states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: sabong@gmail.com.

Jul/Aug 2009