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Some surprising findings surround phakic IOL implantation. At least in one large Midwest refractive practice, implantation of phakic IOLs is accounting for less than 1% of all refractive procedures. The incidence of enhancement procedures using LASIK or PRK is also very low-only 3%. Outcomes after additional excimer laser correction in patients with extreme myopia receiving one phakic IOL (Verisyse, Advanced Medical Optics) have been excellent.
In his large Midwest refractive practice, implantation of phakic IOLs accounts for less than 1% of all refractive procedures. The results have been excellent, however, with only 3% requiring enhancement procedures using LASIK or PRK, said Dr. Lindstrom, clinical professor of ophthalmology, at the University of Minnesota, Minneapolis.
In addition, the outcomes after additional excimer laser correction in patients with extreme myopia undergoing implan-tation of a particular phakic IOL (Verisyse, Advanced Medical Optics [AMO]) have been excellent, he said.
The use of phakic IOLs has many advantages, Dr. Lindstrom noted.
"No tissue is removed. The outcomes in clinical trials have been good. Several studies have shown that the quality of the vision is impressive," he said. In his study, the phakic IOL was implanted using an uncomplicated technique. First, a frown-based corneal scleral incision was made. In many patients, a peribulbar block was used.
Phakic IOL implantation rate
Dr. Lindstrom recounted that, since 1999, a total of 229 eyes had the phakic IOL implanted. During the same 6-year period, more than 30,000 laser refractive procedures have been performed. "Slightly less than 1% of our procedures have been implants of phakic IOLs, which is less than we would have anticipated," he said. Interestingly, since the lens was approved, that number of phakic implantation procedures performed has not increased.
"We also thought that with implantation of phakic IOLs, the enhancement rate would be high. However, enhancement was needed in only eight of the 229 eyes," Dr. Lindstrom said. "The laser [VISX CustomVue, AMO] that has received FDA approval to treat myopia up to –12.75 D for PRK or LASIK was used for the enhancements. Custom PRK was performed on three eyes, custom LASIK on one eye, and standard LASIK on four eyes. The patients with high myopia seem to be very pleased with the outcomes, despite a small residual refractive error."
In the population of patients with the Verisyse IOL implanted, the mean refractive error was –11.7 D. The lowest level of myopia treated with this IOL was –8 D.
"The typical outcome with the patients who underwent an enhancement procedure was residual myopia with some residual astigmatism. With laser enhancement in these eight eyes, we have had excellent outcomes with residual myopia of –0.06 and 0.25 D of astigmatism. Sixty-three percent of patients were 20/20, 88% had 20/25, and 100% had 20/30," Dr. Lindstrom said.
Many of the patients who received this IOL had significant higher-order aberrations, he said.
"There is no doubt that we can implant phakic IOLs and no doubt that we can enhance the procedures," Dr. Lindstrom said. "In many [patients] treated with custom LASIK or PRK and the currently available laser, we can achieve great outcomes.
"The biggest surprise to us was that only 1% of the refractive procedures are phakic IOLs," he concluded. "Our European colleagues had suggested to us that that percentage would be higher. The other surprise was the low rate, about 3%, of enhancement procedures following implantation of the phakic IOLs."