Hyperopic shift in refraction associated with implantation of the single-piece Collamer intraocular lens

To describe reports of refractive hyperopic shift over time following intraocular lens (IOL) implantation, discuss possible etiologies, and suggest preventive and therapeutic treatments.

Multiple U.S. ophthalmic surgical centers; data collection at Staar Surgical, Monrovia, California, USA.

Forty cases displaying a progressive hyperopic shift in refraction after implantation of the single-piece Collamer IOL (Staar Surgical) were reported to the manufacturer out of 160 000 that have been implanted since its commercial introduction in April 2000. A retrospective data analysis of these 40 cases was performed; parameters included the mean refractive change over time, presence of capsular fibrosis, IOL displacement, and outcomes of secondary treatments. Individual case examples are presented.

The mean refractive shift was 1.81 diopters (D) (range 0.25 to 3.75 D) with 5 cases (14%) demonstrating a hyperopic shift greater than 3.0 D. In 38 of the 40 cases, some combination of the following were reported: posterior displacement of the IOL, capsule fibrosis, and/or relief of the condition by performance of a radial or circumferential anterior neodymium:YAG capsulotomy to relieve capsule tension. The use of a small (less than 5.5 mm) capsulorhexis was also associated with cases showing the hyperopic shift.

The most likely etiology was the development of anterior capsule fibrosis, sometimes exacerbated by a small capsulorhexis, which could cause the IOL to move posteriorly, resulting in a hyperopic change in refraction. Previous in vitro testing by the manufacturer ruled out a change in the refractive power of the IOL in the eye as a cause of this phenomenon.