title: Impact of panretinal photocoagulation on optic nerve head parameters.
abstract: BACKGROUND
  To investigate the impact of panretinal photocoagulation (PRP) on quantitative optic nerve head (ONH) assessment in patients with diabetic retinopathy.
  
  
  METHODS
  Eighty eyes of 80 diabetic patients who did not undergo PRP and 45 eyes of 45 subjects with diabetes who underwent PRP were enrolled in the prospective, cross-sectional study. Participants were evaluated by confocal scanning laser ophthalmoscopy (CSLO). The global values of ONH parameters were compared among the groups.
  
  
  RESULTS
  The eyes that had been treated with PRP had a significantly greater rim area (1.84 ± 0.45 vs. 1.68 ± 0.30 mm(2)), smaller cup/disc area ratio (0.14 ± 0.12 vs. 0.19 ± 0.12), smaller linear cup/disc ratio (0.34 ± 0.17 vs. 0.42 ± 0.14) and shallower cup depth (0.15 ± 0.09 vs. 0.18 ± 0.07 mm) than controls (p = 0.021, p = 0.019, p = 0.007, p = 0.04, respectively). On the other hand, PRP-treated eyes were found to have a significantly thinner mean peripapillary retinal nerve fibre layer compared with the eyes in the control group (0.21 ± 0.08 vs. 0.25 ± 0.09 mm; p = 0.029).
  
  
  CONCLUSIONS
  These results suggest that the ONH morphology in eyes treated with PRP may be altered to mask glaucomatous cupping due to PRP itself. Therefore caution must be taken to interpret the CSLO parameters obtained from eyes that have been treated with PRP.
authors.affiliation: MD Ulucanlar Eye Research Hospital, Ankara, Turkey. abcankaya@hotmail.com
authors.forename: Ali Bulent
authors.initials: AB
authors.lastname: Cankaya
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Ozdamar
authors.forename: Solmaz
authors.initials: S
authors.lastname: Ozalp
authors.forename: Seyhan Sonar
authors.initials: SS
authors.lastname: Ozkan
mesh_terms: D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017075:Laser Coagulation / Q000379:methods*; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000473:pathology / Q000601:surgery*; D009901:Optic Nerve Diseases / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity