Long-Term Posterior Capsule Opacification Reduction With Square-Edge PMMA IOL
Ophthalmology, March 2017
In a randomized controlled study, Haripriya et al. compared posterior capsule opacification (PCO) scores and rates of Nd:YAG capsulotomy for a modified square-edge (SE) PMMA intraocular lens (IOL) against 2 other types: round-edge (RE) PMMA or SE hydrophobic acrylic IOLs. They found that at the 9-year follow-up, both the PCO scores and the rates of capsulotomy were significantly lower in the SE-PMMA group.
Many patients in the developing world receive sutureless, manual small-incision cataract surgery, often in conjunction with nonfolding PMMA IOLs. These IOLs, however, are associated with a higher rate of PCO compared with foldable acrylic IOLs. This is a particular problem in areas with limited access to postop care and Nd:YAG. Animal studies suggested that a sharp edge on the optic of a PMMA IOL reduced PCO; thus, the authors developed a modified SE-PMMA, which they evaluated in this study.
The study included 94 patients who were scheduled for bilateral phacoemulsification. All patients had an SE-PMMA IOL implanted in 1 eye; in the fellow eye, 46 patients received an RE-PMMA IOL (group A) and 48 received an SE acrylic IOL (group B). Randomization was used to determine group assignment and which IOL was implanted in the first eye to undergo surgery. The main outcome measures were PCO scores and YAG capsulotomy rates. PCO score was determined objectively by image analysis software grading of standardized retroillumination photos taken annually for the first 5 postoperative years and at year 9.
In both groups A and B, the SE-PMMA IOL had significantly lower PCO scores at 9 years than either of the comparison groups. Moreover, 9-year Nd:YAG capsulotomy rates were 2% for SE-PMMA IOLs versus 37% for RE-PMMA IOLs in group A and 4% for SE-PMMA IOLs versus 10% for SE acrylic IOLs in group B.
The authors noted that creating a squared posterior PMMA optic edge adds approximately $1 to the manufacturing cost of each IOL. However, given the long-term benefit in reducing PCO, they concluded that this modification is highly cost-effective and could significantly reduce the burden of vision-impairing secondary membrane in developing countries.
The original article can be found here.