FDA Phase III Trial Confirms Safety and Efficacy of Artisan Myopic Phakic IOL

By Cheryl Guttman

New Orleans-- Implantation of the Artisan myopic IOL yields predictable and stable refractive outcomes, good uncorrected vision, and minimal complications over the short and long term, Kerry K. Assil, MD, told Refractive Surgery 2001: New Options and New Horizons, here.

Interim results from the US FDA Phase III clinical trial together with 10-year European data showed that among a total of nearly 1300 eyes implanted with the lens, 85% achieved a UCVA of 20/40 or better. Furthermore, the complication rate was low and in fact very similar to that occurring in eyes without the implants, said Dr. Assil who is in private practice at the Sinskey Eye Institute, Santa Monica, CA, and is a clinical trial investigator in the FDA study.

“The high degree of stability of the refractive outcomes with this technology comes as no surprise because there is no prescription-altering wound healing response to corneal sculpting. The excellent safety results might be predicted as well. Since the implanted Artisan myopic IOL sits safely housed over time relatively far from the chamber angle, peripheral corneal endothelium, crystalline lens, and the iris pigment epithelium, it would be unlikely to induce progressive pathologic changes in the eye.”

“Reassuringly, <we are not seeing any evidence of new complications emerging with lengthening follow-up.> However, we acknowledge the need for an even larger series of eyes followed for a longer duration to rule out rare complications or subtle secondary changes that can develop over time,” said Dr. Assil.

In the FDA trial, begun in April 1999, 29 investigators at 22 centres have implanted the Artisan myopic phakic IOL in 775 eyes. The patients had a mean age of about 39 years, their mean preoperative SE was -12.46 D, and the average IOL power implanted was -12.74D. The baseline characteristics for 518 lenses implanted in Europe were very similar.

Refractive Stability from Day One
The refractive outcomes in the FDA trial have been stable from day one after surgery and throughout the two-year follow-up, and predictability has been high. The vast majority of eyes, 89%, were within 1 D of intended refraction and 63% were within +/-0.5 D. Furthermore, of 387 eyes with the implants 71% gained at least one line BSCVA and 20% gained two or more lines, while only three (0.8%) lost a single line of BSCVA, explained Dr. Assil.

“There is some minification effect when looking through a -13.0 D spectacle or even with a contact lens. However, myopic phakic IOLs correct the refractive error closer to the nodal point, and thereby probably increase BSCVA in a high proportion of eyes. And while the spherical equivalent doesn’t shift, we do see some changes in astigmatism during the first several months as a result of the suturing of the limbal wound used for implantation.

“We have tried to take advantage of that issue to correct any underlying astigmatism. Interestingly, in the intermediate follow-up from the US experience as well as in the longer term experience of our European colleagues, we are not seeing any significant secondary astigmatic creep associated with the wound,” noted Dr. Assil.

US Results an Improvement over European
Comparisons between patients in the two continents show that the efficacy and safety results in the US trial even surpass the very favourable European experience. For example, among eyes with a preoperative BSCVA of 20/40 or better in the FDA study, nearly 90% have achieved UCVA of 20/40 or better at six months and 69% are seeing 20/25 or better. In the European cohort, 76.8% of eyes achieved 20/40 or better UCVA.
Furthermore, in the European trial, cataract formation judged as age-related occurred in 2.4% of eyes and 0.8% developed pupillary block. Neither of those events has occurred in the US cohort. Secondary surgery for lens repositioning, removal, or replacement was performed at rates between 2.0% and 3.2% in the European trial. In contrast, none of the US eyes needed lens repositioning and the rates of IOL removal and replacement were each only 0.9%.

Low Endothelial Cell Loss
In addition, Dr. Assil pointed out that in a group of eyes in the US trial with complete data from serial visits over two years endothelial cell loss was only 1.82%.
“That rate is only slightly higher than age-related natural decay. However, we would like further follow-up from a larger number of eyes to confirm the observation from Europe that endothelial cell loss becomes negligible over time,” said Dr. Assil.

Other complications from the US trial include the development of iris synechiae in a single eye - this was first noted at six months and has remained stable up to two years. In addition, pigmented and non-pigmented precipitates have developed on the IOL in about 4% of eyes and night-time halo and glare affect about 4% of patients.
“The precipitates are not deemed clinically significant because they do not appear to affect visual outcomes, and the night-time vision symptoms seem to diminish over time. Furthermore, the symptoms experienced are not typically debilitating and the affected patients remain quite satisfied. We need to remember that <the incidence of glare and halos would likely be the same or higher with contact lens wear in eyes with such high refractive errors,”> commented Dr. Assil.

Patients eligible for enrolment in the US study were 21 to 50 years of age with -5.0 to -20.0 D of myopia, an anterior chamber depth more than 3.2 mm, endothelial cell count more than 2000 cells/mm2, a scotopic pupil larger than the optic diameter, and relatively stable short-term refraction out of contact lenses. Two different models of the Artisan IOL were used. Initially, all eyes were receiving a device with a 5 mm optic that could correct up to -23.5 D of myopia. Later in the series, a 6mm optic became available in powers of up to -15.5 D.

The primary limitation of the Artisan IOL is that the implantation procedure involves a greater amount of manipulation than surgery for foldable models, Dr. Assil said, adding:
“Ninety percent of the surgery is performed using a standard cataract protocol for 5.0- or 6.0-mm PMMA lenses. However, the unique manoeuvres for the enclavation step where the Artisan IOL is attached to the iris takes training and practice. Therefore, surgeons should expect to face a learning curve for this procedure. However, it has been very encouraging that neither progressive problems with IOP nor alarming rates of endothelial cell loss have appeared during the longer term follow-up available in Europe.”

The Artisan FDA myopia trial is sponsored by Ophtec USA, Boca Raton, FL. Dr. Assil has no financial interest in that company.