title: Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Ophthalmology, St Thomas' Hospital, London, England, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: Hollick
authors.forename: D J
authors.initials: DJ
authors.lastname: Spalton
authors.forename: P G
authors.initials: PG
authors.lastname: Ursell
authors.forename: W R
authors.initials: WR
authors.lastname: Meacock
authors.forename: S A
authors.initials: SA
authors.lastname: Barman
authors.forename: J F
authors.initials: JF
authors.lastname: Boyce
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019923:Capsulorhexis; D002386:Cataract / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000009:adverse effects*; D053685:Laser Therapy; D007903:Lens Capsule, Crystalline / Q000473:pathology* / Q000601:surgery; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D019904:Polymethyl Methacrylate / Q000009:adverse effects*; D012826:Silicone Elastomers / Q000009:adverse effects*; D014792:Visual Acuity
chemical_list: D012826:Silicone Elastomers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D019904:Polymethyl Methacrylate