Sharp-edged intraocular lenses (IOLs) are less likely to lead to posterior capsule opacification (PCO) compared with round-edged IOLs in patients undergoing bilateral cataract surgery, according to review results published in the Cochrane Database of Systematic Reviews.
In comparing the effects of varying IOL optic edge designs on PCO following cataract surgery, researchers conducted a systematic review and meta-analysis of randomized controlled trials. The prespecified primary outcome for the review was the proportion of eyes with Nd:YAG capsulotomy 1 year following surgery; secondary outcomes included PCO score, best corrected distance visual acuity (BCDVA), and quality of life in the same timeframe.
Ten studies, including 1065 people and 1834 eyes, comparing sharp- and round-edged IOLs were included in the review. Eight of these studies were within-person studies, with 1 eye receiving a sharp-edged IOL and the fellow eye receiving a round-edged IOL. Studies were conducted in 3 European countries, India, Japan, and the United Kingdom.
Participants in the included studies had a diagnosis of bilateral age-related cataract; those with ocular sight-threatening differences like glaucoma, diabetic retinopathy, and age-related macular degeneration, among others, were excluded. The intervention in all studies included uncomplicated cataract surgery in both eyes with implantation of either a sharp- or round-edged IOL.
At 1 year, there were “few” cases of Nd:YAG capsulotomy, according to researchers: 1 in 371 in the sharp-edged group and 4 in 371 in the round-edged group. Effect estimates were in favor of sharp-edged IOLs, although confidence intervals were wide (odds ratio [OR], 0.30; 95% CI, 0.05-1.74).
At 2, 3, and 5 years, a similarly reduced risk of Nd:YAG capsulotomy in sharp-edged IOLs and round-edged IOLs was noted; however, the number of Nd:YAG capsulotomy events increased over a longer follow-up period, allowing this effect to be more precisely measured over time. At 2 years, the risk ratio (RR) was 0.35 (95% CI, 0.16-0.80) in 703 eyes across 6 studies with 89 fewer cases per 1000. At 3 years, the RR was 0.21 (95% CI, 0.11-0.41) in 538 eyes from 6 studies with 170 fewer cases per 1000, and at 5 years, the RR was 0.21 (95% CI, 0.10-0.45) in 360 eyes across 4 studies with 331 fewer cases per 1000. Nine and 12-year data were only available from 1 included study.
All included studies reported a PCO score: 4 reported the Automated Quantification of After-Cataract (AQUA) score, 4 reported the Evaluation of PCO (EPCO) score, and 2 reported another method of quantifying PCO. Due to the nature of the reporting, it was not possible to pool these data. However, all studies “consistently reported a statistically significant lower average PCO score with sharp-edged IOLs,” according to researchers. This evidence was judged to be of moderate certainty.
LogMAR visual acuity score was lower in eyes that received sharp-edged IOLs; however, this difference was small and “likely to be clinically unimportant” at the 1-year mark (mean difference, -0.06 logMAR; 95% CI, -0.12 to 0; 2 studies with 153 eyes). At longer follow-up periods, similar effects were noted but the data remained non-statistically significant and was, per researchers, less fully reported. Mean difference at 2 years was -0.01 logMAR (95% CI, -0.05 to 0.02; 2 studies with 311 eyes) and -0.09 logMAR at 3 years (95% CI, -0.22 to 0.03; 3 studies with 117 eyes). Five-year data were only available from 1 study.
No studies reported on patient quality of life, and only low-certainty evidence was available for adverse events. This evidence, though, did not suggest any difference of note between the 2 groups.
Overall, the studies were “poorly reported” and risk of bias was noted across “1 or more domain” in several studies. Some outcomes were imprecisely measured—particularly those with shorter follow-up time—but results were largely consistent.
“This review provides evidence that sharp-edged IOLs are likely to be associated with less PCO formation than round-edged IOLs, with less Nd:YAG capsulotomy,” the researchers concluded. “We are less confident about vision being clearer and the lower need for laser surgery for eyes given sharp edged-lenses. Further research is likely to increase our confidence in these results.”
Maedel S, Evans JR, Harrer-Seely A, Findl O. Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery. Cochrane Database Syst Rev. 2021;8(8):CD012516. doi: 10.1002/14651858