Refractive lens exchange increases retinal detachment risk

Manchester, England-Retinal detachment (RD) is a significant risk in refractive lens exchange (RLE) surgery for high myopia, said Emanuel S. Rosen, MD.

Dr. Rosen, visiting professor, department of vision sciences, University of Manchester, England, presented a review of the literature examining the rate of RD in the general population and among myopic eyes after lens removal surgery with IOL implantation.

His summary showed there was a 0.018% rate of RD in the general population that was increased by Kelman phacoemulsification 100-fold overall and 200-fold in myopic eyes (axial length >25 mm). The risk was also greater in eyes that suffered complications during lens removal, especially capsular tear, anterior vitrectomy, or vitreous loss.

In reviewing the literature on this topic, Dr. Rosen pointed out that in addition to high myopia, younger age seems to increase the risk of RD after lens removal surgery. A recent retrospective study of 1,793 patients in a New Zealand community who have undergone phacoemulsification found the overall risk was 1.17%. However, it was 5.17% among patients under 50 years old versus only 0.64% in the over 70-year-old age group.

"Remember, it is the under 50-year-old age group that makes up the patient population for RLE," he said.

Dr. Rosen also presented the results of a meta-analysis he undertook based on a review of papers published over the past decade (1995 to 2005) that had reported rates of RD after lens extraction and IOL implantation in myopic eyes. A total of 21 papers were identified that included 6,522 eyes. In that series, 117 eyes suffered pseudophakic RD (1.8%, one in 56 eyes). Among the individual papers, the RD rates ranged from 0 to 8.1%.

"A number of variables that differ among these studies can account for the variation in their results but that also makes it impossible to reach any hard conclusions about outcomes," Dr. Rosen said. "Long-term case control studies of a high volume of myopic eyes undergoing RLE would be very valuable to help us to define the risk better."

RD rate of 8%

Among those papers, an RD rate of 8% was reported by both Ripandelli et al. in 2003 and Colin et al. in 1999. The former study was based on 930 highly myopic eyes undergoing cataract surgery. Refractive error ranged from –15 to –30 D and axial length from 29.7 to 35.5 mm. The follow-up duration was 36 months, and the rate of RD in fellow, unoperated eyes was 1.2%. Colin et al. reported a 7-year follow-up of 52 eyes of 30 patients that had undergone RLE for high myopia. The results showed the rate increased with higher myopia.

Dr. Rosen also presented data from his personal series of 583 eyes with axial lengths from 24 to 31 mm. Most of the cases involved cataract surgery rather than RLE. During up to 8 years of follow-up, the rate of RD was 0.3%.

Because the risk of RD is thought to be increased after crystalline lens removal because the procedure causes volumetric changes that predispose to vitreoretinal pathology, retinal prophylaxis prior to lens exchange surgery would be expected to have a marginal effect on the risk.

"That concept is consistent with the experience of Colin who found an 8% rate of RD in spite of retinal prophylaxis," Dr. Rosen said.

Dr. Rosen added that RLE is associated with other retinal risks. cystoid macular edema is one potential complication. In contrast to RD, it affects hyperopic patients more often than myopic patients and also tends to be transient rather than permanent.