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New Orleans- Six-month clinical trial results demonstrate that the Artisan phakic toric IOL (PTIOL) offers a safe and effective method for correcting moderate-to-high amounts of regular astigmatism in both myopic and hyperopic eyes, reported Burkhard Dick, MD, assistant professor of ophthalmology, University of Mainz, Germany, during the 2001 Fall Symposium of the International Society of Refractive Surgery.
Data from 70 eyes showed the iris-fixated Artisan PTIOL reduced preoperative spherical and astigmatic errors with high predictability and good stability and was associated with excellent visual outcomes and strong patient satisfaction.

<“With this device we now have a method for correcting all refractive error with a single procedure.> I am convinced this option will increase and its acceptance among surgeons and patients will be very high because of the excellent results,” said Dr. Dick, who was the principal investigator of the study.

The toric version of the Artisan phakic IOL measures 8.5-mm in overall length, features a 5.0 mm convex-concave optic, and is similar to the models for treating myopia or hyperopia except the toric optic features a spherical anterior surface and a sphero-cylindrical posterior surface.

Two toric models are available and the selection between them depends on the axis of the cylinder. An A model (PTIOL-00) has the axis of cylinder passing through the enclavation site of the haptics, and it is recommended for eyes where the axis of cylinder is between zero and 45 degrees or from 135 to 180 degrees. Eyes where the axis of cylinder lies between 45 and 135 degrees should be implanted with the B model (PTIOL-900) for which the axis of cylinder is oriented 90 degrees to the haptics.
Available powers can correct -3.0 to -20.5 D of myopia or from +2.0 to +12 D of hyperopia along with 2.0 to 7.5 D of astigmatism. Power increments are in 0.5 D steps, which is very helpful for targeting the individual’s refraction and achieving excellent results, noted Dr. Dick, adding that customized IOLs can also be obtained on a special need basis.

The European clinical trial of the Artisan PTIOL was conducted at 15 investigational centers and aimed to evaluate 60 eyes at six months. However, that goal was exceeded and 70 eyes were followed to six months. There were 43 female eyes and 27 male eyes and the patients had a mean age of 35 years (range 22 to 59 years).

Mean preoperative cylinder was reduced in all eyes from 3.7 D to 0.7 D at six months, and the dramatic reduction achieved in preoperative astigmatism was demonstrated as well by comparing the pre- and postoperative doubled-angle plots (Holladay).
The procedure also demonstrated good predictability for correcting ametropia - all eyes were within 1.0 D of intended correction (spherical equivalent) - and for correcting astigmatism - all eyes were within zero to 2.0D of intended correction. Off-axis fixation accounted for three of four outliers (>1.0D), and could be attributed to the steep learning curve of the surgeons with this new lens, Dr. Dick said

“Although the Artisan PTIOL is not foldable and needs to be implanted through a 5-mm incision, induced astigmatism does not appear to be a problem. We use a sclerocorneal incision for implantation and found that in our series of about 30 eyes, the surgery induced an average of about 0.53 D of astigmatism. That is not very much, and it can be integrated into the preoperative power calculation,” he added.
Mean SE decreased from a preoperative value of -5.68 D to -0.57 D at one week and remained stable to 6 months.

The good refractive efficacy translated into excellent functional results. Uncorrected visual acuity was 20/40 or better in 88.6% of eyes. Best corrected visual acuity improved in 65.7% of cases and was maintained in the rest. The efficacy index, calculated as postoperative UCVA/preoperative BSCVA was 1.03.

<“After implantation of the Artisan PTIOL, patients saw better or at least as good without correction as they did with spectacles before the surgery.> I am somewhat doubtful if similar results can be achieved with laser surgery,” said Dr. Dick.

Patients were also asked to rate their satisfaction under normal, bright, and low light conditions using a scale of one (very poor) to ten (excellent). At six months, the mean rating was approximately 9.0 or higher in all three settings.

The toric version of the Artisan phakic IOL demonstrated the same favourable safety profile as the myopic version has in large studies. IOP was unaffected and measurement of endothelial cell counts showed a slight change (mean 4.5%) after six months.
Dr. Dick evaluated the stability of the implant’s fixation at 6 months after surgery in 21 eyes implanted at his center. Investigating the deviation of IOL fixation from target axis, he found the phakic IOL had deviated a mean of four degrees (range zero to 13) from its target axis.

“For a good outcome, it is crucial that the cylinder axis be marked accurately and the Artisan PTIOL be implanted at the right axis. These results from our follow-up support the concept that with its unique method of fixation, there is a good guarantee that this IOL will not rotate off-axis over time,” commented Dr. Dick.

Different axis marking strategies can be used to assure correct IOL alignment. Depending on the surgeons’ preference, the enclavation spots on the iris can be marked with a laser, the paracenteses on the limbus may be marked with a pen, or, as Dr. Dick favours, orientation can be guided by iris structure.

He added that when implanting the Artisan PTIOL in hyperopic eyes, it is important to keep in mind that the visual axis may not lie in the middle of the pupil. Therefore, obtaining optimal results may depend on decentering the IOL slightly in hyperopes.
IOL power calculations are performed by the manufacturer based on the van der Heijde formula and require the following data: manifest refraction at 12.0 mm vertex, cycloplegic refraction at 12.0 mm vertex, anterior chamber depth, keratometry value, and corneal diameter. Dr. Dick noted that he also routinely evaluates potential candidates with computerized corneal topography to exclude individuals with irregular astigmatism. In addition, he evaluates the periphery of the anterior chamber to assure the angle is not flat and there is enough space for the enclavation sites.

He added that the excellent results obtained with the Artisan PTIOL in the multicenter trial reflect in part the fact that he and his fellow investigators all had long-term experience with the Artisan phakic IOL.

His co-investigators include: Jorge Alio y Sanz, MD, Marco Bianchetti, MD, Camille Budo, MD, B J Christiaans, MD, M Alaa El-Danasoury, MD Jose Guell, MD, Jorg Krumeich, MD, M Landesz, MD, Francisco Loureiro, MD, Greg PM Luyten, MD, Antonio Marinho, MD, M Rahhal, MD, Urs Thomann, MD, and Jan Venter, MD.

Dr. Dick is not a paid consultant to Ophtec and has no other financial interest in that company.