title: Stereoscopic analysis of optic nerve head parameters in primary open angle glaucoma: the glaucoma stereo analysis study.
abstract: OBJECTIVE
  The Glaucoma Stereo Analysis Study (GSAS), a cross sectional multicenter collaborative study, used a stereo fundus camera to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients and investigated the relationships between these parameters and patient characteristics.
  
  
  METHODS
  The study included 187 eyes of 187 subjects with primary open angle glaucoma or normal tension glaucoma (male: female  = 100: 87, age  = 61±9 years). Stereo pairs of ONH photographs were made with a stereo fundus camera (nonmyd WX). ONH morphological parameters were calculated with prototype analysis software. In addition to 35 standard parameters, we defined three novel parameters: disc tilt angle, rim decentering, and the absolute value of rim decentering. The correlation between each parameter and patient characteristics was analyzed with Spearman's rank correlation coefficient.
  
  
  RESULTS
  Patient characteristics included refractive error of -3.38±3.75 diopters, intraocular pressure (IOP) of 13.6±2.6 mmHg, and visual field mean deviation (MD) of -4.71±3.26 dB. Representative ONH parameters included a horizontal disc width of 1.66±0.28 mm, vertical disc width of 1.86±0.23 mm, disc area of 2.42±0.63 mm2, cup area of 1.45±0.57 mm2, and cup volume of 0.31±0.22 mm3. Correlation analysis revealed significant negative associations between vertical cup-to-disc ratio (0.82±0.08) and MD (r = -0.40, P<0.01) and between disc tilt angle (10.5±12.5 degrees) and refractive error (r = -0.36, P<0.01). Seventy-five percent of the eyes had a positive value for rim decentering (0.30±0.42), indicating that rim thinning manifested more often as an inferior lesion than a superior lesion.
  
  
  CONCLUSIONS
  We used stereoscopic analysis to establish a database of ONH parameters, which may facilitate future studies of glaucomatous changes in ONH morphology.
authors.affiliation: Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yokoyama
authors.affiliation: Department of Ophthalmology, Shimane University Faculty of Medicine, Shimane, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanito
authors.affiliation: Department of Ophthalmology, Fukui-ken Saiseikai Hospital, Fukui, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nitta
authors.affiliation: Department of Ophthalmology, Sapporo Teishin Hospital, Sapporo, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Katai
authors.affiliation: Department of Ophthalmology, St. Marianna University School of Medicine, Kawasaki, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kitaoka
authors.affiliation: Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Omodaka
authors.affiliation: Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Tsuda
authors.affiliation: Kowa Company, Ltd., Nagoya, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nakagawa
authors.affiliation: Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Nakazawa
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy / Q000379:methods*; D009900:Optic Nerve / Q000473:pathology*; D012680:Sensitivity and Specificity