The incidence of the development of cataracts is low after implantation of an implantable collamer lens (ICL), 1.96% over 5 years of follow-up. The common risk factors for cataract development in association with an ICL are patients aged more than 40 years, high myopia, surgeon learning curve, shallow anterior chamber depth, and male gender.
Chicago-Clinically significant cataracts develop infrequently after implantation of an implantable collamer lens (ICL), specifically 1.96% over 5 years of follow-up, according to Kjell Gundersen, MD, PhD, who reported his findings at the annual meeting of the American Society of Cataract and Refractive Surgery. Common risk factors for development of a cataract included patients aged more than 40 years, high myopia, surgeon learning curve, shallow anterior chamber depth, and male gender.
In the study, cataract was defined as nuclear sclerosis, based on age alone, or on anterior subcapsular cataract and presumed to have been induced iatrogenically, said Dr. Gundersen, head of the Cataract Department, Privatsykehuset Haugesund, Haugesund, Norway. A clinically significant cataract was defined in the study under discussion as one that resulted in a decrease in more than two lines of vision, included the presence of visually disruptive glare, and required explanation of the ICL.
"Historically, reports have been published of very high incidences of cataract formation following ICL implantation," he said. "However, reviewing those reports must be done with caution because older studies in the literature did not differentiate between cataracts that were visually relevant and those that were not."
Dr. Gundersen and his colleagues conducted a retrospective analysis of 610 eyes with an ICL implanted between 2002 and 2007 at the Privatsykehuset Haugesund. Patients were aged 18 to 59 years and were divided almost evenly between men and women. Of these patients, 85% had either myopia or myopic astigmatism, 10% were hyperopic, and 5% had mixed astigmatism or hyperopic astigmatism.
Dr. Gundersen performed the surgeries, all of which were uncomplicated. The preoperative refractive errors ranged from –21 to 10 D, and astigmatism ranged from 0 to –6 D. More than 400 of the ICLs implanted were spherical and the remainder were toric ICLs. The anterior chamber depths ranged from 2.9 to 4.7 mm.
"Our analysis identified 27 cases of lenticular opacities, of which 12 cases (1.96%) had formation of a clinically significant cataract and required explantation of the ICL," Dr. Gundersen said. "Of the 12 cases, 11 patients had been implanted with a spherical ICL and one with a toric ICL."
When the various factors were evaluated to determine the risk of cataract formation, investigators found that the time from cataract implantation to lens explantation varied greatly, i.e., from 12 to 52 months. They also noted that all of the eyes that developed a cataract had undergone surgery during the first 3 years during which Dr. Gundersen implanted ICLs, suggesting that a learning curve had been in play.
"It is fair to say that surgical experience does have a substantial role in the development of cataract after implantation of these lenses," he said.
All patients except one who developed a cataract after lens implantation were aged more than 40 years at the time of implantation. Most of the cases also had myopia that exceeded –12 D, except for one patient, aged 59 years, with hyperopia.
"When we combined the factors of age and myopia, 11 (92%) of the 12 eyes that developed a cataract after implantation of an ICL were either in patients older than 40 years or with a refraction greater than –12 D of myopia," he said. The eyes with significant cataracts had significantly more shallow anterior chambers. In addition, the vast majority of patients (10 of 12 eyes) who developed clinically significant cataracts were men.
Following explantation of the ICL, cataract removal, and implantation of an IOL, the visual acuity (VA) recovered nicely, according to Dr. Gundersen, and there was less variability in the VA after IOL implantation compared with after ICL implantation.
"The refraction was stable after the ICL/IOL exchange for manifest refraction, sphere, and cylinder," he said. "An interesting observation was that both the efficacy and the safety indices tended to be better after re-implantation of the IOL. This leads me to wonder if these eyes had a pre-existing cataract that we overlooked before the surgery to implant the ICL."