Study finds risk of cataracts from ICL implantation is low
July 10, 2008
At the recent annual meeting of the American Society of Cataract and Refractive Surgery, Kjell Gundersen, MD, PhD, reported the findings of a 5-year study of the risk of cataract after implantable collamer lens (ICL) implantation surgery.
ICL (also called implantable contact lens) implantation is a lens-based refractive surgery usually reserved for the correction of relatively high amounts of myopia or hyperopia.
Dr. Gundersen noted that previous studies have found a high incidence of cataracts after ICL surgery, but that these studies did not differentiate between minor lens opacities that did not affect vision and clinically significant cataracts that did.
He also said that improvements in ICL designs may have reduced the risk of cataracts formation in the years since these studies were published.
Study design
Dr. Gundersen and colleagues performed a retrospective analysis of 610 eyes that underwent ICL implantation performed by Dr. Gundersen at Privatsykehuset Haugesund, a private hospital in southwest Norway, between 2002 and 2007.
Patients in the study ranged in age from 18 to 59 years, with approximately an equal number of men and women.
The majority of the patients (85%) had either myopia or myopic astigmatism. The remainder had farsightedness, farsightedness with astigmatism, or mixed astigmatism.
The magnitude of the patients' pre-operative refractive errors ranged from -21 diopters (D) of myopia to 10 D of hyperopia, with up to 6 D of astigmatism.
Study results
Over the 5-year period of the study, the researchers identified 27 cases of post-operative lens opacities (4.4%), but only 12 of these (1.96%) were clinically significant cataracts that required removal of the ICL and cataract surgery.
All eyes that developed cataracts had undergone the ICL surgery during the first 3 years of the study, suggesting that their may have been a learning curve for the surgeon.
"It is fair to say that surgical experience does have a substantial role in the development of cataract after implantation of these lenses," said Dr. Gundersen.
Also, all patients who developed cataracts were over 40 years old at the time of their ICL procedure, and most of them had pre-operative myopia greater than -12 D.
(It should be noted that the first patients in the study to have the ICL procedure were followed for a period of 5 years after surgery and the last patients were followed for less than a year.)
All patients who developed cataracts were successfully treated by surgical removal of both the ICL and the cataractous lens and implantation of a typical intraocular lens (IOL) used in cataract surgery.
Results support findings of previous FDA study
The results of this study support the findings of an earlier clinical trial of ICL implantation for myopia required by the US Food and Drug Administration (FDA).
The FDA study looked at 526 eyes that underwent the ICL procedure and monitored the eyes for up to 8 years after surgery.
Researchers in the FDA study concluded that approximately 6% to 7% of eyes develop lens opacities at 7+ years following ICL implantation, but only 1% to 2% develop opacities that progress to clinically significant cataracts during the same period.
Like Dr. Gundersen and his colleagues, the researchers in the FDA study found that older patients and those with very high degrees of pre-operative myopia have a greater risk of developing cataracts after ICL refractive surgery.