title: A randomized clinical trial of early panretinal photocoagulation for ischemic central vein occlusion. The Central Vein Occlusion Study Group N report.
abstract: OBJECTIVE
  To answer whether prophylactic panretinal photocoagulation (PRP) in ischemic central vein occlusion (CVO) prevents development of 2 clock hours of iris neovascularization or any angle neovascularization (TC-INV/ANV) or whether it is more appropriate to apply PRP only when TC-INV/ANV occurs.
  
  
  METHODS
  Multicenter randomized controlled clinical trial in eyes with ischemic CVO. Eyes were assigned to immediate prophylactic PRP (90 eyes) or to frequent close observation (91 eyes). If TC-INV/ANV developed, untreated eyes received PRP and previously treated eyes received supplemental PRP.
  
  
  RESULTS
  In both groups, TC-INV/ANV developed less often in prophylactically treated than untreated eyes, but the difference was not statistically significant when adjusted for baseline imbalance. Treatment of TC-INV/ANV was followed by prompt regression (within 1 month) in 18 (56%) of 32 previously untreated eyes and in 4 (22%) of 18 eyes that had had prophylactic treatment. All eyes except eight eventually stabilized without neovascularization. TC-INV/ANV was correlated with the amount of nonperfused retina (P = 0.0001) and extent of retinal hemorrhage (P = 0.03). Males were at higher risk than females for TC-INV/ANV (P = 0.01), as were patients with occlusions of less than one month duration (P = 0.01).
  
  
  CONCLUSIONS
  Prophylactic PRP does not totally prevent TC-INV/ANV, and prompt regression of TC-INV/ANV in response to PRP is more likely to occur in eyes that have not been treated previously. The authors recommend careful observation with frequent follow-up examinations in the early months (including undilated slit-lamp examination of the iris and gonioscopy) and prompt PRP of eyes in which TC-INV/ANV develops.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D005654:Fundus Oculi; D006801:Humans; D007498:Iris / Q000098:blood supply; D007511:Ischemia / Q000503:physiopathology / Q000601:surgery*; D017075:Laser Coagulation; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000517:prevention & control; D011183:Postoperative Complications; D012169:Retinal Vein / Q000503:physiopathology / Q000601:surgery*; D012170:Retinal Vein Occlusion / Q000503:physiopathology / Q000517:prevention & control / Q000601:surgery*; D012307:Risk Factors; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology