title: Comparison of visual acuity outcomes in predominantly classic vs occult lesions in age-related macular degeneration treated with photodynamic therapy.
abstract: OBJECTIVE
  To determine if patients with occult with no classic and predominantly classic (PC) choroidal neovascular membranes have clinically equivalent visual outcomes after treatment with photodynamic therapy (PDT) with verteporfin.
  
  
  METHODS
  This is a retrospective, observational cohort study. Two hundred and seventy-seven consecutive patients with occult or PC choroidal neovascularization secondary to age-related macular degeneration treated with PDT were included. The main outcome was the difference in mean change in Early Treatment of Diabetic Retinopathy Study (ETDRS) acuity lost from baseline in occult vs PC lesions, with the minimal clinically important difference (MCID) set at 7.5 letters.
  
  
  RESULTS
  At baseline, 131 patients had occult and 146 had PC choroidal neovascularization. Twelve-month follow-up data were available for 94 occult and 110 PC participants. Occult patients lost an average of 8.7 letters (1.9 lines), and patients in the PC group an average of 10.0 ETDRS letters (two lines) over 12 months. The mean letters lost at 12 months was not significantly different between the groups, and the MCID was not detected (difference=1.3 letters; P=0.411; 95% confidence interval (-2.3, 5.6)). Patients with occult lesions required a mean of 2.99 treatments vs a mean of 2.96 treatments in the PC group (out of a possible 4; P=0.172).
  
  
  CONCLUSIONS
  We were not able to detect a clinically important difference in mean change in visual acuity with PDT treatment between patients with occult and PC lesions.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of British Columbia, Columbia, Canada. mpotter@ interchange.ubc.ca
authors.forename: M J
authors.initials: MJ
authors.lastname: Potter
authors.forename: S M
authors.initials: SM
authors.lastname: Szabo
authors.forename: W W
authors.initials: WW
authors.lastname: Li
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020256:Choroidal Neovascularization / Q000209:etiology / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008268:Macular Degeneration / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011166:Porphyrins / Q000627:therapeutic use; D012189:Retrospective Studies; D016896:Treatment Outcome; D000077362:Verteporfin; D014792:Visual Acuity
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D000077362:Verteporfin