title: Observational study of the development of diabetic macular edema following panretinal (scatter) photocoagulation given in 1 or 4 sittings.
abstract: OBJECTIVE
  To compare the effects of single-sitting vs 4-sitting panretinal photocoagulation (PRP) on macular edema in subjects with severe nonproliferative or early proliferative diabetic retinopathy with relatively good visual acuity and no or mild center-involved macular edema.
  
  
  METHODS
  Subjects were treated with 1 sitting or 4 sittings of PRP in a nonrandomized, prospective, multicentered clinical trial. Main Outcome Measure Central subfield thickness on optical coherence tomography (OCT).
  
  
  RESULTS
  Central subfield thickness was slightly greater in the 1-sitting group (n = 84) than in the 4-sitting group (n = 71) at the 3-day (P = .01) and 4-week visits (P = .003). At the 34-week primary outcome visit, the slight differences had reversed, with the thickness being slightly greater in the 4-sitting group than in the 1-sitting group (P = .06). Visual acuity differences paralleled OCT differences.
  
  
  CONCLUSIONS
  Our results suggest that clinically meaningful differences are unlikely in OCT thickness or visual acuity following application of PRP in 1 sitting compared with 4 sittings in subjects in this cohort. More definitive results would require a large randomized trial. Application to Clinical Practice These results suggest PRP costs to some patients in terms of travel and lost productivity as well as to eye care providers could be reduced.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT00687154.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Brucker
authors.forename: Haijing
authors.initials: H
authors.lastname: Qin
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Antoszyk
authors.forename: Roy W
authors.initials: RW
authors.lastname: Beck
authors.forename: Neil M
authors.initials: NM
authors.lastname: Bressler
authors.forename: David J
authors.initials: DJ
authors.lastname: Browning
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Elman
authors.forename: Adam R
authors.initials: AR
authors.lastname: Glassman
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Gross
authors.forename: Craig
authors.initials: C
authors.lastname: Kollman
authors.forename: John A
authors.initials: JA
authors.lastname: Wells
mesh_terms: D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D017075:Laser Coagulation / Q000379:methods*; D054020:Lasers, Gas / Q000627:therapeutic use*; D008269:Macular Edema / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012160:Retina / Q000473:pathology; D019233:Retreatment; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology