Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial

Am J Ophthalmol. 2000 May;129(5):577-84. doi: 10.1016/s0002-9394(99)00447-x.


Purpose: To compare the visual outcome, percentage of posterior capsular opacification, and laser capsulotomy rates with polymethylmethacrylate, silicone, and hydrogel intraocular lens implants at 1 and 2 years postoperatively.

Methods: Ninety-three eyes of 93 patients were randomized to receive a polymethylmethacrylate, silicone, or hydrogel intraocular lens implant. A standardized surgical protocol was followed by a single surgeon using phacoemulsification with capsulorhexis; any patients with surgical complications were excluded, and all patients received standardized medication and follow-up. Patients were examined at days 1 and 7, months 1, 3, and 6, and years 1 and 2 after surgery. At each assessment, best-corrected logMAR visual acuity and Pelli-Robson contrast sensitivity were measured. Posterior capsular opacification was objectively assessed by digital retroillumination imaging with the use of a dedicated software program and calculated as the percentage area of opacified capsule. Laser capsulotomy was performed if the eye had lost 2 lines of visual acuity with a clinically opaque capsule.

Results: At 2 years postoperatively, the mean percentage area of posterior capsular opacification for hydrogel lenses was 63%; for polymethylmethacrylate, 46%; and for silicone, 17%. Hydrogel intraocular lenses were associated with 17% more posterior capsule opacification than were polymethylmethacrylate lenses (95% confidence interval, 1-33; P =. 037) and 45% more than were silicone lenses (95% confidence interval, 33-58; P <.0001) at 2 years. Polymethylmethacrylate lenses had 28% more posterior capsule opacification than silicone lenses (95% confidence interval, 13-43; P <.0001) at 2 years. Twenty-eight percent of patients with hydrogel intraocular lenses required an Nd:YAG laser posterior capsulotomy at 2 years, compared with 14% with polymethylmethacrylate, whereas no patients with silicone lenses needed a capsulotomy (P =.014). Visual acuity was not significantly different among the three groups, but patients with silicone intraocular lenses had significantly better contrast sensitivity than those with hydrogel lenses (P =.046).

Conclusions: Intraocular lenses made of this specific hydrogel were associated with a significantly higher degree of posterior capsular opacification and more laser capsulotomies than polymethylmethacrylate and silicone intraocular lenses.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Aged, 80 and over
  • Capsulorhexis
  • Cataract / epidemiology
  • Cataract / etiology*
  • Cohort Studies
  • Female
  • Humans
  • Hydrogel, Polyethylene Glycol Dimethacrylate / adverse effects*
  • Laser Therapy
  • Lens Capsule, Crystalline / pathology*
  • Lens Capsule, Crystalline / surgery
  • Lens Implantation, Intraocular
  • Lenses, Intraocular / adverse effects*
  • Male
  • Middle Aged
  • Polymethyl Methacrylate / adverse effects*
  • Silicone Elastomers / adverse effects*
  • Visual Acuity*


  • Silicone Elastomers
  • Hydrogel, Polyethylene Glycol Dimethacrylate
  • Polymethyl Methacrylate