title: Effect of macular edema on optical coherence tomography signal strength.
abstract: OBJECTIVE
  The purpose of this study was to examine the effect of macular edema (ME) on Stratus optical coherence tomography (OCT) (Stratus OCT, Carl Zeiss Meditec, Dublin, CA) signal strength (SS).
  
  
  METHODS
  Part 1: Macular OCT was performed in 57 eyes with ME, at 2 different time points with different degrees of ME. The relationships between SS change and change in center point thickness and total macular volume in two scans were examined. Part 2: In 54 eyes with ME, Stratus OCT examinations with macular thickness mapping and retinal nerve fiber layer analysis protocols were performed. The paired values of SS obtained with two scan protocols were compared. The relationship between SS difference between two test protocols with center point thickness and total macular volume was evaluated.
  
  
  RESULTS
  Part 1: There was a significant correlation between SS change and the change in center point thickness and total macular volume in 2 consecutive scans. Part 2: Maximum SS obtained during macular OCT examination was significantly less than that obtained during retinal nerve fiber layer OCT. Significant correlations were observed between the difference in SS obtained in two scan protocols and center point thickness as well as total macular volume.
  
  
  CONCLUSIONS
  Macular edema decreases macular OCT SS. In patients with ME, SS obtained during macular OCT examination was significantly lower than that obtained during retinal nerve fiber layer OCT examination.
authors.affiliation: Department of Ophthalmology and Poostchi Ophthalmic Research Center, Shiraz University of Medical Sciences, Shiraz, Iran. hosseinashraf@yahoo.com
authors.forename: Hamid
authors.initials: H
authors.lastname: Hosseini
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Razeghinejad
authors.forename: Sarah
authors.initials: S
authors.lastname: Nowroozizadeh
authors.forename: Peyman
authors.initials: P
authors.lastname: Jafari
authors.forename: Hossein
authors.initials: H
authors.lastname: Ashraf
mesh_terms: D001369:Axons / Q000473:pathology*; D003930:Diabetic Retinopathy / Q000150:complications; D006801:Humans; D008269:Macular Edema / Q000175:diagnosis* / Q000209:etiology; D011446:Prospective Studies; D012160:Retina / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012170:Retinal Vein Occlusion / Q000150:complications; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence