Age, trauma risk factors for opacification after ICL implantation

A study suggests that older crystalline lenses are more vulnerable to opacification after trauma during phakic IOL surgery.

ByJared Schultz

Older age, low endothelial cell density and the occurrence of intraoperative trauma are risk factors for crystalline lens opacification after implantation of a posterior chamber phakic IOL, according to researchers in Vienna. Low central vaulting of the phakic IOL, previously believed to be a risk factor for crystalline lens opacification, was not found to be a significant factor with 3 years of follow-up, the researchers said.

Birgit Lackner, MD, and colleagues at the University of Vienna Medical School implanted STAAR Surgical’s ICL Version 4 (since renamed the Visian ICL) in 76 eyes of patients with myopia in a prospective study to assess the correlation between progression of postoperative crystalline lens opacification and factors such as vaulting and endothelial cell density.

“In our series, four of six early opacifications and four of five progressive opacifications occurred after difficult surgery in older patients, which suggests that intraoperative trauma to the crystalline lens is the leading cause of early opacification,” the study authors said. Their report is published in the November 2004 issue of the Journal of Cataract & Refractive Surgery.

The patients were evaluated preoperatively and at 1, 3, 6, 12, 24 and 36 months postoperatively to determine uncorrected and best corrected visual acuity. Eyes that developed lens opacification were followed for at least 12 months to assess the degree and characteristics of the opacification.

Lens opacification occurred in 11 eyes (14.5%), and the researchers found that its occurrence was correlated with intraoperative trauma to the crystalline lens, age older than 50 years at the time of surgery and the decrease of endothelial cell density throughout the observation period. The degree of ICL vaulting was not correlated with lens opacification risk, they said.

Of the 11 eyes, six eyes (55%) had best corrected visual acuities that were stable within ± 0.5 lines, and five had progressive VA loss, losing between 3.5 and 0.5 lines. Three of the eyes with progressive opacifications had a one- or two-line loss of BCVA from preoperative values and subsequently underwent cataract surgery, the study authors said.

The researchers noted that the cases of opacification seen in the study had no overall negative effect on postoperative outcomes. The mean uncorrected visual acuity in all eyes increased from 0.04 ± 0.04 preoperatively to 0.42 ± 0.27 at 1 month.

“Compared to preoperative measurements, they (on the whole) had a substantial improvement of visual acuity, even with their opacification,” Dr. Lackner said in an e-mail interview with Ocular Surgery News.

The role of age

According to the report, the mean age of patients who developed opacifications was 48.3 ± 7.4 years, and the patients who developed progressive opacifications tended to be older than patients with stable opacifications.

The report called age the most important factor in the likelihood of lens opacification. The authors noted that four of six cases with early opacifications developed after particularly difficult and prolonged surgical procedures and that all five cases with late opacifications occurred in patients over the age of 50 years. Eight of the 11 opacifications were in patients older than 45 years, and all of the instances of surgical trauma were in patients older than 50.

The researchers noted in their report that STAAR Surgical recently included a cutoff age of 45 years in its recommendations for use of the lens due to the potential for the vulnerability of the crystalline lens to increase with age.

The report also raises questions as to whether applying a strict age limit for ICL implantation would decrease opacification rates or merely postpone them.

“By applying the recently suggested age criteria, the opacification rate in our series would drop from 14.5% to 5%,” the report noted, if age by itself is a causative factor.

Beyond age, Dr. Lackner said that researchers have yet to learn the specific causes of progressive opacification vs. stable early opacification.

“At present we do not know enough about the pathogenesis of opacification to reliably differentiate the causes for stable or progressive cases,” he said.

Vaulting issues

Although the vaulting of the lens did not correlate with opacification, the report suggested that further research is needed on this issue. The Visian ICL was designed to leave a larger space between the phakic IOL and the natural lens than previous models of the STAAR lens, Dr. Lackner said. However, the vaulting measurements published so far represent the distance between the ICL and the crystalline lens under static laboratory conditions, she explained.

For Your Information:

Birgit Lackner, MD, can be reached at the department of ophthalmology, University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria; +40400-7900; e-mail: birgit.lackner-funovics@meduniwien.ac.at. Dr. Lackner and colleagues have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned.

STAAR Surgical Company, maker of Visian ICL, can be reached at 1911 Walker Ave., Monrovia, CA 91016 U.S.A.; +1-626-303-7902; e-mail: info@STAAR.com.

Reference:

Lackner B, Pieh S, et al. Long-term results of implantation of phakic posterior chamber intraocular lenses. J Cataract Refract Surg. 2004;30:2269-2276.

Jared Schultz is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses geographically on Europe and the Asia-Pacific region.