title: Utility of digital stereo images for optic disc evaluation.
abstract: OBJECTIVE
  To assess the suitability of digital stereo images for optic disc evaluations in glaucoma.
  
  
  METHODS
  Stereo color optic disc images in both digital and 35-mm slide film formats were acquired contemporaneously from 29 subjects with various cup-to-disc ratios (range, 0.26-0.76; median, 0.475). Using a grading scale designed to assess image quality, the ease of visualizing optic disc features important for glaucoma diagnosis, and the comparative diameters of the optic disc cup, experienced observers separately compared the primary digital stereo images to each subject's 35-mm slides, to scanned images of the same 35-mm slides, and to grayscale conversions of the digital images. Statistical analysis accounted for multiple gradings and comparisons and also assessed image formats under monoscopic viewing.
  
  
  RESULTS
  Overall, the quality of primary digital color images was judged superior to that of 35-mm slides (P < 0.001), including improved stereo (P < 0.001), but the primary digital color images were mostly equivalent to the scanned digitized images of the same slides. Color seemingly added little to grayscale optic disc images, except that peripapillary atrophy was best seen in color (P < 0.0001); both the nerve fiber layer (P < 0.0001) and the paths of blood vessels on the optic disc (P < 0.0001) were best seen in grayscale. The preference for digital over film images was maintained under monoscopic viewing conditions.
  
  
  CONCLUSIONS
  Digital stereo optic disc images are useful for evaluating the optic disc in glaucoma and allow the application of advanced image processing applications. Grayscale images, by providing luminance distinct from color, may be informative for assessing certain features.
authors.affiliation: Department of Ophthalmology, University of Pennsylvania, Scheie Eye Institute, Philadelphia, Pennsylvania 19104-3309, USA. stone@mail.med.upenn.edu
authors.forename: Richard A
authors.initials: RA
authors.lastname: Stone
authors.forename: Gui-Shuang
authors.initials: GS
authors.lastname: Ying
authors.forename: Denise J
authors.initials: DJ
authors.lastname: Pearson
authors.forename: Mayank
authors.initials: M
authors.lastname: Bansal
authors.forename: Manika
authors.initials: M
authors.lastname: Puri
authors.forename: Eydie
authors.initials: E
authors.lastname: Miller
authors.forename: Judith
authors.initials: J
authors.lastname: Alexander
authors.forename: Jody
authors.initials: J
authors.lastname: Piltz-Seymour
authors.forename: William
authors.initials: W
authors.lastname: Nyberg
authors.forename: Maureen G
authors.initials: MG
authors.lastname: Maguire
authors.forename: Jayan
authors.initials: J
authors.lastname: Eledath
authors.forename: Harpreet
authors.initials: H
authors.lastname: Sawhney
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009798:Ocular Hypertension / Q000175:diagnosis; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D010781:Photography; D015203:Reproducibility of Results