For the often problematic cases of ametropia with high cylinder values, traditional treatments, such as LASIK and PRK, have notable limitations in their corrective capabilities. Attempts to correct high refractive defects with these procedures have commonly yielded negative results, including low predictability, regression, corneal ectasia, and poor quality of vision in dim illumination, largely due to significant changes in corneal curvature and small optical zones.1 There are, however, several intraocular procedures that make such corrections possible, because they do not modify the optical corneal surface. Among these procedures are phacoemulsification of the crystalline lens (which should be treated cautiously with younger patients due to the ensuing loss of accommodative ability and the possibility of retinal complications) and the implantation of phakic IOLs. These lenses use a small optical zone to correct high ametropia, while maintaining the compatibility of their thickness with the ocular anatomy.2
Many surgical approaches to correct ametropia with high astigmatism have been proposed. Roberto Zaldivar, MD, of Argentina and his associates introduced the bioptics procedure, which entails a LASIK procedure after phakic IOL implantation. This technique is intended to correct myopic refractions of greater than 20.0 D.3 My own research team, meanwhile, developed the Adjustable Refractive Surgery technique to treat refractions exceeding -14.0 D, while maintaining an optical zone of 6 mm.4 Currently, however, we are actively researching a relatively new IOL.
THE ARTISAN TORIC LENS
In 1986, Jan Worst, MD, and Paul Fechner, MD, modified the existing iris-claw (OPHTEC, Groningen, Netherlands) lens, which was designed for the correction of aphakia, and gave the lens a negative power to be used in the treatment of high myopia. The name of the lens was changed to Artisan in 1998, but there were no significant adjustments to its design. Theoretically, implantation of this lens eliminates the need for multiple surgeries to correct high values of sphere and cylinder and greatly reduces visual recovery time and the occurrence of complications.5,6
Since 1997, my colleagues and I have implanted 285 Artisan lenses, but, due to its fairly recent market introduction, we have implanted only 14 Artisan Toric lenses. These implants, however, belong to a multicenter European study that includes 70 eyes. The candidates for these procedures have eyes with astigmatism higher than 1.5 D, myopia greater than -8.0 D, or hyperopia exceeding +3.0 D. The available lens powers range from 2.0 D to 7.5 D of astigmatism, from -3.0 D to -20.5 D of myopia, and +2.0 to +12.0 D hyperopia, with power increments of 0.5 D. Two models of the lens are available. Model A, with an axis at 0º (the axis of the claw), is recommended for eyes with an axis of cylinder between 0º and 45º, or from 135º to 180º. Model B's axis is at 90º (again, the axis of the claw), and this lens is recommended for eyes with an axis of cylinder between 45º and 135º.7 Patients must show an endothelial cell count greater than 2,300 cells/mm and an anterior chamber depth greater than 3.2 mm.7
The surgical technique involves difficulties in attaching the haptics to the iris, making the attainment of exact lens centration difficult to perfect. The surgeon implants the lens through a 5.2-mm incision, and creates two lateral ports for the insertion of the instruments necessary to attach the lens.8 The dioptric power calculation is derived from the patient's refractive error, anterior chamber depth, and keratometric values.7
We analyzed the results in terms of BCVA, UCVA, subjective refraction, endothelial cell count, intraocular pressure, an examination with a slit lamp, a retinal examination, the satisfaction of the patient, and a follow-up evaluation at 12 months.
No patients experienced a diminution of BCVA, each improving by one or more lines (Snellen chart) with respect to preoperative refractive status. Postoperative spherical equivalents were between -1.0 and +0.50 D, and there was no incidence of endothelial cell loss. In the entire multicenter study, only 4.5% of cases experienced endothelial cell loss at 6 months. After the suture removal, refractions have not changed. Every patient has reported a high degree of satisfaction.
Our results, as well as those of the European multicenter study, indicate that the implantation of the Artisan Toric Lens is safe, offers high predictability, and enables surgeons to reduce or eliminate high ametropia with only one procedure. The lens is also useful for correcting high astigmatism after penetrating keratoplasty, which makes it an effective alternative to corneal refractive surgery. Prospective studies with long-term follow-up will provide more information concerning the safety of this procedure, especially regarding endothelial cell count.
Felicidad Manero, MD, is an ophthalmologist at the Instituto de Microcirugía Ocular in Barcelona, Spain. He does not hold a financial interest in any of the products mentioned herein. Dr. Manero may be reached at +34 93 253 1500; firstname.lastname@example.org
Fortino Velasco, MD, is a fellow at the Cornea and Refractive Surgery Unit at the Instituto de Micro cirugía Ocular in Barcelona, Spain. He does not hold a financial interest in any of the products mentioned herein. Dr. Velasco may be reached at +34 93 253 1500; email@example.com
José Lucena, MD, is Master of the Anterior Segment at the Instituto de Microcirugía Ocular in Barcelona, Spain. He does not hold a financial interest in any of the products mentioned herein. Dr. Lucena may be reached at +34 93 253 1500; firstname.lastname@example.org
1. Seiler T, Holschbach A, Derse M, et al: Complications of myopic photorefractive keratotomy with the excimer laser. Ophthalmology 101:153-60, 1994
2. Zaldivar R, Ricur G, Oscherow S: The phakic intraocular lens implant: In-depth focus on posterior chamber phakic IOL. Cur Opin Ophthal 11:22-34, 2000
3. Zaldivar R, Davidorf JM, Oscherow S, et al: Combined posterior chamber phakic intraocular lens and laser in situ keratomileusis: Bioptics for extreme myopia. J Refract Surg 15:299-308, 1999
4. Güell JL, Vázquez M, Gris O: Adjustable refractive surgery: 6 mm Artisan lens plus laser in situ keratomileusis for the correction of high myopia. Ophthalmology 108; 945-52, 2001
5. Fechner PU, Worst JGF: A new concave intraocular lens for the correction of high myopia. Eur J Implant Refract Surg 1:41-43, 1989
6. Cisneros A, Cervera M, Perez-Torregosa VT, et al: Lentes fáquicas y alta miopia: Resultados a medio y largo plazo. Archivos de la Sociedad Española de Oftalmología 69:49-358, 1995
7. Werner L, Apple D, Izak A, et al: Phakic anterior chamber intraocular lenses. Int Ophthalmol Clin 41:133-151, 2001
8. Pop M, Mansour M, Payette Y: Ultrasound biomicroscopy of the iris-claw phakic intraocular lens for high myopia. J Refract Surg 15:632-635, 1999