Phakic IOL yields strong outcomes in selected active US military personnel

Phakic IOL implantation safely improved visual acuity at 3 months in active military personnel with myopia who were deemed unsuitable candidates for laser vision correction, a study found.

The authors reported results obtained with the Visian Implantable Collamer Lens (ICL, STAAR Surgical).

“The results at 3 months and beyond have been very impressive, really,” Gregory D. Parkhurst, MD, the corresponding study author, said. “In terms of visual symptoms, I would say that we got reports of excellent vision.”

Dr. Parkhurst said refractive surgery in military personnel is valuable because spectacles and contact lenses are impractical in combat settings.

“Refractive surgery in the military is a really important program because there’s a job-specific reason to be performing surgery,” he said.

In addition to offering a viable surgical option for patients who do not qualify for laser refractive surgery, phakic IOLs have other advantages, according to Dr. Parkhurst.

“I would expect that we see an increased use of phakic IOLs and lens-based refractive surgery, not only in the military but across refractive surgery at large,” he said. “There are just so many advantages with not permanently altering the cornea, especially in these high myopes. And when it is time to have cataract surgery someday, it’s going to be very easy to predict the IOL power that you need and offer a variety of presby-correcting IOLs, which may not be available to former corneal refractive surgery patients.”

Study results were published in the Journal of Refractive Surgery.

Patients, protocols

The retrospective study included 135 eyes of 69 patients who underwent implantation of the Visian ICL over a 14-month period in 2008 and 2009. Mean patient age was 30.9 years. Analysis of 3-month postoperative outcomes included 128 eyes.

“We started off implanting just a few ICLs because it was a newer technology to our refractive surgery program. We weren’t really sure where we were going to go with it. We are now over 4 years out and seeing more refractive centers adding the technology to their armamentarium,” Dr. Parkhurst said.

Indications for ICL implantation were abnormal corneal topography in 37% of eyes, thin predicted post-LASIK residual stromal bed in 32%, history of dry eye disease in 13%, thin central corneas in 11% and other conditions in 7%. The patient group did not include pilots or Air Force personnel, who are not permitted to undergo ICL implantation.

Mean preoperative spherical equivalent refraction was –6 D, and mean preoperative astigmatism was 0.65 D. Mean preoperative logMAR corrected distance visual acuity was –0.08 D (Snellen equivalent 20/16.6).

Mean targeted spherical equivalent refraction was –0.21 D.

Preoperative biometric measurements included corneal topography, anterior chamber depth, axial length and white-to-white measurement to determine ICL sizing.

“The other way is to do ultrasound biomicroscopy to actually measure the ciliary sulcus length,” Dr. Parkhurst said. “We ended up investing in UBM, and that’s how we do it now. But these were our first patients when we first got started. At that time we were doing white-to-white, which proved to be very effective.”

Patients were examined 1 day, 1 week, 1 month and 3 months postoperatively.

Data on manifest refraction were available for 128 eyes at 3-month follow-up.

Results, conclusions

Study results showed that mean postoperative spherical equivalent refraction was –0.19 D. Refractive correction was within 0.5 D of emmetropia in 90% of eyes and within 0.75 D in 99%.

Mean postoperative logMAR corrected distance visual acuity was –0.13 (Snellen equivalent 20/14.8); 33% of eyes gained at least one line of corrected distance visual acuity and 13% gained at least two lines. One eye lost one line. No eyes lost two or more lines.

Mean uncorrected distance visual acuity was –0.08 (Snellen equivalent 20/16.6). Postoperative uncorrected distance visual acuity equaled or exceeded preoperative corrected distance visual acuity in 108 eyes (80%).

“The vast majority of the patients would say that their vision now with ICLs was the best they had ever seen before,” Dr. Parkhurst said. “We saw that objectively, where many of them had a better postoperative uncorrected vision than they had a preoperative best corrected vision. That’s a pretty rare outcome for us to see.”

Results showed no significant intraoperative or postoperative complications. One patient underwent ICL explantation because of excessive vault, which was not a study outcome measure.

“But that’s definitely an important thing to look at,” Dr. Parkhurst said. “One of the concerns with this technology, of course, is cataract formation. We know that if there’s a low or flat vault, there may be a higher risk of cataract development at young ages. This is particularly important in a young patient population like those in the military. So far, there has been a less than a 1% incidence of cataract.”

Further study is warranted to analyze long-term outcomes, the study authors said. – by Matt Hasson

Editors’ note: Dr. Parkhurst’s statements in this article are his opinion as a physician and not those of the U.S. government or the U.S. Army.

Reference:

• Parkhurst GD, Psolka M, Kezirian GM. Phakic intraocular lens implantation in United States military warfighters: a retrospective analysis of early clinical outcomes of the Visian ICL. J Refract Surg. 2011;27(7):473-481.

• Gregory D. Parkhurst, MD, can be reached at McFarland Eye Centers, 17200 Chenal Parkway, Suite 440, Little Rock, AR 72223; email: Gregory.Parkhurst@gmail.com.
• Disclosure: Dr. Parkhurst has no relevant financial disclosures.