Artisan Toric IOL (Ophtec BV, Groningen, Netherlands) (Figure 1) implantation is effective for the reduction of anisometropia and astigmatism. Toric lens implantation also allows patients who are contact lens intolerant after keratoplasty to wear spectacles. In a study published in Ophthalmology, 16 eyes from 16 patients who were contact lens intolerant or unable to wear spectacles, were suitable for spectacle correction after the IOL implantation.1 Both the original study and a 3-year follow-up concluded that all patients were suitable for spectacle correction after implantation. The follow-up study found, however, that there was continuing endothelial cell loss from 6 months to 3 years postoperatively. In three cases, corneal graft failure developed.
The Artisan Toric lens has a convex-concave toric optic with a spherical anterior surface and a spherocylindrical posterior surface. This single-piece lens is composed of PMMA and is manufactured using a compression molding technology. The Toric IOL is iris-claw fixated, and it has a 5-mm optical zone. Refractive error, refractive cylinder power, anterior chamber depth, and topographically derived kertometric dioptric values were inserted into the Van der Heijde formula to calculate the dioptric power of the lens for two meridians. The axis of the cylinder identified by the subjective refraction was used to determine the axis of surgical enclavation.
AVAILABLE DIOPTRIC POWERs
The power of the lens was chosen to obtain emmetropia (14 eyes) or a postoperative spherical equivalent of -1.00 D (2 eyes) resulting from myopia in the untreated eyes. The intraocular lens is available in dioptric powers of -3.00 D to -20.50 D; 2.00 to 12.00 D; and in cylindrical powers of 2.00 D to 7.50 D.
Before surgery the horizontal and vertical axis for lens enclavation should be marked. A two-plane 5.3-mm corneoscleral incision should be centered at 12 o'clock. Two stab incisions should be performed at 2 and 10 o'clock and directed toward the enclavation sites. After an intracameral injection of acetylcholine and under an ophthalmic viscoelastic device (Healon GV; Advanced Medical Optics, Santa Ana, California), the lens should be introduced by forceps. After gentle rotation, the lens should fixate with a disposable enclavation needle in the marked axis. A slit iridotomy performed at 12 o'clock will avoid papillary block glaucoma. The wound suture should consist of three to four interrupted 10/0 nylon sutures, and a topical antibiotic can be used four times daily for 3 weeks, and three times daily for 1 week after the procedure.
According to our study,1 the above procedures were used on the 16 eyes with a mean ±standard deviation of the preoperative refractive cylinder of -6.66 ±1.93 D (range, -4.00 D to -10.00 D). That deviation was reduced to -1.42 ±0.78 D at the final follow-up examination (12 months). Spherical equivalent was reduced from -4.90 ±5.50 D before surgery to 0.96 ±0.86 D at the final follow-up. The UCVA and BCVA were more than or equal to 20/40 in 42% and 100% of eyes, respectively. There was no loss of BCVA and a gain of at least two lines in 50% of eyes (Figure 2). The percent reduction in refractive astigmatism, topographical astigmatism, and anisometropia of defocus were 78.0 ±11.5%, 20.3 ±34.9%, and 77.0 ±12.0%, respectively. Astigmatism correction index was 102.8 ±18.6%. Patients reported that their satisfaction increased from 3.2 to 8.3 after implantation on a scale of one to 10. Additionally, no complications (ie, cystoid macular edema, chronic inflammation of the anterior chamber, or retinal detachment) were noted.
PREFERRED TECHNIQUE
Until now, LASIK seemed to be the preferred technique for correction of anisometropia and astigmatism after keratoplasty.2-4 However, our study1 showed that use of Artisan Toric IOL, with a power range of 7.50 D of cylinder and -20.50 D of myopia to 12.00 D of hyperopia, provides a wide field for correction. To my knowledge, the reduction of the refractive cylinder by 91 ±21% (without any enhancements) is better than in most reported LASIK series. The reduction of refractive astigmatism after LASIK varies from 48% to 88%.
Improving the UCVA of 20/40 or better from 0% to 50% of the cases in the study, illustrates the efficacy of implanting the Artisan Toric IOL. In most of the LASIK series I have reviewed, UCVA better than 20/40 varied from 28% to 74%. With respect to short-term safety, no eye lost BCVA, and eight of 16 eyes gained at least two lines.
Concerns have been raised with respect to the development of complications (eg, endothelial cell loss, chronic inflammation, and cystoid macular edema) after Artisan lens implantation. A study using fluorometry showed inflammation comparable with cataract surgery at 6-months after surgery. According to Menezo et al,5 there are no chronic inflammation by slit-lamp examination, and cystoid macular edema with concomitant loss of BSCVA and was not seen in the immediate postoperative phase.6
Still, a cautious use of Artisan Toric lens implantation is needed, because we found a progressive endothelial cell loss in these corneas with a compromised endothelium. The mean endothelial cell loss was 13.8 ±18.7%, 21.2 ±21.8%, 29.6 ±27.3%, and 30.4 ±32.0% at 6, 12, 24 and 36 months, respectively. Probably, the higher cell loss is explained by the increased vulnerability of the corneal graft endothelium that usually has low cell densities and may cause a higher rate of endothelial cell loss.7 If we correct the endothelial cell loss values for the expected cell loss induced by the penetrating keratoplasty there appears to be an additional cell loss of 6% to 7% per year. I recommend more patients with a longer follow up of up to 5-years, to help identify the risk factors for progressive endothelial cell loss and a randomized study of the Artisan Toric lens implantation versus LASIK.
Rudy M.M.A. Nuijts, MD, PhD, is a an associate professor of ophthalmology at the department of ophthalmology at Academic Hospital Maastricht, in the Netherlands. He states he has no financial interest in the products or companies mentioned. Dr. Nuijts may be reached at rnu@compaqnet.nl.
Up Front | Nov 2006
Using the Artisan Toric IOL
How to manage postkeratoplasty astigmatism with this lens.
Rudy M.M.A. Nuijts, MD, PhD
