Phakic lenses provide safe, precise refractive correction

San Francisco-In the ongoing debate over the superiority of refractive procedures, phakic lenses are receiving increasing attention because they preserve and improve the quality of vision, according to Jos? L. Guell, MD, PhD.

"Phakic IOLs have been receiving more and more attention recently," said Dr. Guell, associate professor of ophthalmology, Autonoma University of Barcelona, and director of the Cornea and Refractive Surgery Unit, Instituto de Microcirugia Ocular de Barcelona, Barcelona. He described the factors responsible for that renewed interest during Cornea Day 2006 at the annual meeting of the American Society of Cataract and Refractive Surgery.

He explained that while implantation of phakic IOLs was one of the first refractive procedures for the correction of ametropia, the IOLs were originally abandoned because of the frequency and severity of complications associated with them.

From the late 1990s to the early 2000s, a great deal of interest developed in the reversibility of refractive procedures. A few studies conducted in patients with high myopia compared LASIK and phakic IOLs during that time.

"In every one of the studies that compared phakic IOLs with LASIK for the treatment of high myopia, the results showed that the phakic IOLs produced better quality of vision than LASIK," he said.

In his practice, Dr. Guell and colleagues undertook a comparison of phakic IOLs and LASIK for the correction of high myopia. They considered seven factors: refractive results, stability, adjustability, reversibility, patient perception of the type of surgery, complications, and optical quality. They reviewed all publications on phakic IOLs in order to make their determinations.

Considering the refractive results, especially efficacy and predictability, and not considering the need for enhancement surgeries in LASIK and phakic IOLs, "there are no significant differences between LASIK and phakic IOLs in efficacy and predictability or in correction of high myopia. In addition, there is no significant difference in the rates of complications between the two procedures, taking into account the limitations at the time of comparing the different results published in the peer-reviewed literature," he said.

The results with phakic IOLs, he pointed out, are stable, adjustable, and reversible and are much better than with LASIK.

However, one stumbling block for phakic IOLs is that the patient perception of LASIK is better than that of phakic IOLs, because of the differences between an intraocular procedure and a surface procedure, he said.

Regarding the last consideration, the quality of vision in high myopia was a bit more difficult to compare. Dr. Guell explained that when using a theoretical linear ablation pattern the degree of applanation of the cornea is, surprisingly, not important to maintain high-quality vision. But, in practical terms, when doing a standard correction to reduce the anterior corneal power down to 38 D, and with optimized ablations because they preserve better postoperative asphericity, down to 36 D, the optical quality then begins to diminish in LASIK.

The surgical skill with which LASIK for high myopia is performed is not important, because the quality of vision (the modulation transfer function and the point spread function) begins to deteriorate from 38 D.

"This, however, is not the case with phakic IOLs. In cases with –10 or –12 D of correction, the modulation transfer function and the point spread function are preserved," he emphasized.

In his practice, Dr. Guell prefers to use the Artisan Verisyse-Veriflex IOL (Advanced Medical Optics, Ophtec BV) because of its proper centration in patients with high myopia. The IOL is placed deeper in the anterior chamber compared with the angle-supported IOLs, and the IOL is fixed and obviously can be used in toric corrections and in the future to correct other vectorial aberrations. In addition, the Verisyse lens preserves iris vascularization compared with angle-supported IOLs, he explained. Finally, the foldable model (Veriflex) can be introduced through a 3.0-mm incision.