Long-term effect of sharp optic edges of a polymethyl methacrylate intraocular lens on posterior capsule opacification: a randomized trial

Ophthalmology. 2005 Nov;112(11):2004-8. doi: 10.1016/j.ophtha.2005.06.021. Epub 2005 Sep 15.


Purpose: To compare the posterior capsule opacification (PCO) inhibiting effect of a 3-piece polymethyl methacrylate (PMMA) intraocular lens (IOL) with a sharp optic edge design with that of the round-edged version of the same IOL during a 5-year period.

Design: Randomized patient- and examiner-masked clinical trial with intraindividual comparison.

Participants: Thirty-two patients with bilateral age-related cataract (64 eyes).

Methods: Each study patient had phacoemulsification cataract surgery in both eyes and received a sharp optic edge PMMA IOL in one eye and a round optic edge PMMA IOL in the fellow eye (both by Dr Schmidt in Germany). Follow-up examinations were at 1 week, 1 month, 1 year, 3 years, and 5 years. Digital retroillumination images were taken from each eye. The amount of posterior capsule opacification was assessed objectively by means of automated image analysis software (Automated Quantification of After-Cataract) at 1 year, 3 years, and 5 years after surgery.

Main outcome measure: Posterior capsule opacification score: 0-10.

Results: The sharp optic edge IOL showed significantly less regeneratory and fibrotic PCO at 1 year, 3 years, and 5 years after surgery. The mean AQUA PCO score was 5.12 for the round-edge and 2.49 for the sharp-edge IOL (scale, 0-10; P<0.001) at 5 years. The mean difference among patients for the PCO score in the eye implanted with the sharp optic edge versus the score in the eye with the round optic edge was 2.83 at 5 years (95% confidence interval, 1.66-4.00). Due to the large number of neodymium:yttrium-aluminum-garnet laser capsulotomies that were performed (12 in the round-edge group and 4 in the sharp-edge group), there was no significant difference in visual acuity between both groups at any time point.

Conclusions: Compared with the round-edge version, the sharp optic edge design of a 3-piece PMMA IOL led to significantly less PCO at 1 year, 3 years, and 5 years after surgery. However, the sharp optic edge did not lead to complete PCO prevention during this follow-up period. This finding has implications for the design of PMMA IOLs used for cataract surgery, especially in the developing world.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Cataract / etiology*
  • Cataract / pathology
  • Double-Blind Method
  • Follow-Up Studies
  • Humans
  • Lens Capsule, Crystalline / pathology*
  • Lens Implantation, Intraocular
  • Lenses, Intraocular*
  • Phacoemulsification*
  • Polymethyl Methacrylate*
  • Postoperative Complications*
  • Prosthesis Design


  • Polymethyl Methacrylate