Phakic IOLs: do they fit in a refractive surgery practice?

April 1, 2006

Minneapolis, MN?Phakic IOLs are a powerful fit for any practice wanting to provide comprehensive refractive surgery, but surgeons who decide to offer this technology need comprehensive training to learn about patient selection, IOL sizing, and surgical technique, according to David R. Hardten, MD.

"Phakic IOLs play an important role in managing higher ametropias, can be additive to other types of refractive surgery already being offered, and the implantation technique is very learnable for practitioners already doing intraocular surgery," reported Dr. Hardten, adjunct associate professor of ophthalmology, University of Minnesota, and director, refractive surgery, Minnesota Eye Consultants, Minneapolis. "However, good outcomes depend on a number of issues that cannot be covered in a single talk or short session."

He spoke at the refractive surgery subspecialty day meeting sponsored by the International Society of Refractive Surgery of the American Academy of Ophthalmology, Chicago.

Dr. Hardten illustrated the clinical performance of the iris-fixated Verisyse IOL (AMO/VISX) and the foldable, posterior chamber Visian ICL (STAAR Surgical) by summarizing results from myopia clinical trials. Among eyes seen at 3 years in the FDA study of the Verisyse IOL, 92% achieved 20/40 or better uncorrected visual acuity (UCVA), only 6% lost 2 or more lines of BSCVA, and 49% had a gain in BSCVA. Endothelial cell counts remained very stable and were similar to those in patients who have not had IOL surgery. In addition, patient satisfaction levels were very high.

Dr. Hardten said similar results have been achieved with the Visian ICL. For example, among patients with preoperative BSCVA of 20/25 or better that was targeted for emmetropia, more than 90% achieved UCVA of 20/40 or better.

"Now, even better results may be attained in clinical use since we have access to IOLs in half-diopter power steps rather than just full-diopter increments. Surgeon-adjusted nomograms have also led to improved outcomes for phakic IOLs, and also for LASIK," he said. "And, while custom LASIK has now been approved for higher myopia, phakic IOLs still have a role for patients needing higher levels of correction."

Although only recently available on the market, phakic IOLs already account for 5% of Dr. Hardten's refractive surgery practice. Patients he considers a good fit for this option include those with prepresbyopic myopia with refractive errors of –8.0 to –16.0 D. People with lower myopia are also candidates if they have a thin cornea or atypical topography, while those with a higher level of myopia may be considered if they are young and expected to be tolerant of a smaller-diameter IOL (for the iris claw phakic IOL) or residual myopia.

"However, phakic IOLs do not correct presbyopia, so that in presbyopic moderate to high myopia and presbyopic hyperopia, refractive lens exchange with a multifocal or accommodating IOL may be a better choice. Patients with hyperopia in particular tend to be ideal candidates for refractive lens exchange because of anterior chamber anatomy," Dr. Hardten said.

He stressed that one size or style implant does not fit all patients. For the iris-fixated IOL, both 5.0-mm and 6.0-mm optic models are available. The larger optic is generally preferred for minimizing problems with glare and halos, but it is only available in powers up to –15.0 D while the power range is up to –20.0 D for the smaller-optic implant.

There are also certain anatomic considerations for determining if a patient is a good candidate. Relative thickness of the iris should be evaluated because the lens vaults over the iris.

"If the iris has a very thick collarette, there can be touch and inflammation," Dr. Hardten said.