Implantation of the newest Implantable Collamer Lens phakic intraocular lenses (V4b and V4c) did not cause cataract formation in highly myopic patients.
Take-home message: Implantation of the newest Implantable Collamer Lens phakic intraocular lenses (V4b and V4c) did not cause cataract formation in highly myopic patients.
Reviewed by Jose F. Alfonso, MD, PhD
Oviedo, Spain-Cataract formation has been associated with the first phakic IOLs introduced into the marketplace. However, newer models seem to be on the way to solving that problem. The latest models, the Visian Implantable Collamer Lenses (ICL) (models V4b and V4c, STAAR Surgical), did not result in cataract development in any eyes in which they were implanted.
Because ICLs meet a need in the refractive surgery arena for patients with high refractive levels, they have been gaining in popularity and not just because of their effectiveness.
In addition, they are safe, predictable, and provide stable vision for patients with high levels of myopia, hyperopia, and astigmatism.
However, the downside has been development of clinically relevant cataracts in 2.1% of patients in less than a year following implantation and in 2.7% before the 3-year mark, according to the FDA data. The culprit in the development of anterior subcapsular cataracts seems to be the contact between the phakic IOL and the natural crystalline lens.
In light of this, Jose Alfonso, MD, PhD, and colleagues, conducted a retrospective, nonrandomized, clinical study in which they evaluated the performances of three phakic IOLs, the V4, V4b, and V4c models, in 3,420 eyes of 1,898 patients who underwent surgery in one center. The mean patient age was 31.2 years (range, 18 to 50 years). The mean spherical refractive error was -7.27 (range, -26.5 to 12.5 D).
Of the 3,420 eyes, 1,531 were implanted with the V4 phakic IOL, 1,108 with the V4b model, and 781 with the V4c model. The mean follow-up times, respectively, were 6 years (range, 1 to 12 years), 2.0 years (range, 1 3o 3 years), and 6 months (range, 3 to 24 months), according to Dr. Alfonso, associate professor at the University of Oviedo, School of Medicine and head of the Cornea and Lens Department of the Fernández-Vega Universitary Institute, Oviedo, Spain.
He reported that cataracts developed in 21 (0.61%) of 15 patients with the V4 phakic IOL. No cataracts developed in eyes that received the other two phakic IOL models.
Cataract and vaulting correlation
Seven (47%) of the 15 patients were younger than 40 years of age and eight (53%) were 40 years and older (mean age, 39.43 years). The mean spherical equivalent in these patients was -10.1 D. In three (14%) eyes, the phakic IOL power was less than -10.5 D, in four (19%) eyes between -10.5 and -13.5 D, and in 14 (67%) eyes higher than -13.5 D. The mean vault distance in these eyes was 103 µm. The mean time to cataract development was 4.2 years postoperatively.
The investigators published their findings in the Journal of Cataract and Refractive Surgery (2015;41:800-805).
The relationship between cataract development and vaulting has been of interest to surgeons. Previous studies have found that there is substantially less vaulting in patients who are older. A 2003 study by Gonvers and associates (J Cataract Refract Surg 2003;29:918-924) reported that central vaulting that exceeded 90 µm protects against cataract development.
However, 150 µm is recommended because of decreasing vaulting over time. In a previous study, Dr. Alfonso and colleagues reported a direct relationship between low vaulting and cataract formation, with all patients who developed cataracts having less than 100 µm of vaulting (Graefes Arch Clin Exp Ophthalmol 2010;248:1827-35).
With phakic IOLs with high refractive power, the peripheral vaulting becomes an issue in cataract development, and Dr. Alfonso advised surgeons to consider this in patients who are highly myopic.
In addition, patient age seems to be a factor in cataract formation, with older patients developing cataracts more often than younger ones. Dr. Alfonso has no financial interest in this subject matter.
In the study under discussion, the authors concluded, “…implantation of the [ICL] phakic IOL led to a very low incidence of cataract formation. The prevalence of cataract was higher in patients who were older, had high refractive errors, and had older phakic IOL models.”
Jose F. Alfonso, MD, PhD
Dr. Alfonso did not indicate any proprietary interest in the subject matter.