title: Influence of the disc-fovea angle on limits of RNFL variability and glaucoma discrimination.
abstract: OBJECTIVE
  To determine factors affecting the disc-fovea angle (DFA), and to test the hypotheses that adjusting for DFA improves limits of retinal nerve fiber layer (RNFL) variability in normal subjects or enhances performance of RNFL measures for glaucoma detection.
  
  
  METHODS
  Disc-fovea angle was measured on scanning laser ophthalmoscope fundus images from 170 eyes (110 normal and glaucoma subjects). The DFA measurements were repeated in 24 eyes. The relationship between DFA and various anatomic variables was explored. Main outcome measures were changes in 95% RNFL prediction limits or glaucoma discrimination after adjusting for DFA. We also explored the angle between temporal raphe and horizontal meridian in 19 eyes with nasal field defects limited to one hemifield.
  
  
  RESULTS
  Average mean deviation and DFA were -0.1 (±1.2) dB and -6.6° (±3.4°) and -4.1 (±3.3) dB and -7.9° (±3.9°) in the control and glaucoma groups, respectively (P < 0.001 and = 0.029). The average difference between DFA repeat measurements was 2.0° (±1.8°). Predictors for DFA were female sex (P = 0.004), smaller disc area (P = 0.006), and glaucoma diagnosis (P = 0.019). The absolute change in sectoral RNFL thickness was 6.1 (±3.9) and 4.6 (±3.1) μm in control and glaucoma subjects, respectively. Retinal nerve fiber layer prediction limits improved in 5, 9, and 10 o'clock sectors (P < 0.02). Discrimination ability for the best-performing RNFL sector did not improve (P = 0.936). The average angle between temporal raphe and horizontal meridian was 0.8° (±0.8°).
  
  
  CONCLUSIONS
  Disc-fovea angle measurements demonstrated fair intersession repeatability. While adjusting for DFA improved RNFL prediction limits in some sectors, it did not enhance glaucoma detection.
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Navid
authors.initials: N
authors.lastname: Amini
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Sara
authors.initials: S
authors.lastname: Nowroozizadeh
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Nila
authors.initials: N
authors.lastname: Cirineo
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Sharon
authors.initials: S
authors.lastname: Henry
authors.affiliation: Department of Computer Science and Engineering, University of California-San Diego, La Jolla, California, United States.
authors.forename: Ted
authors.initials: T
authors.lastname: Chang
authors.affiliation: Department of Biomathematics, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Tom
authors.initials: T
authors.lastname: Chou
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Anne L
authors.initials: AL
authors.lastname: Coleman
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Joseph
authors.initials: J
authors.lastname: Caprioli
authors.affiliation: Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Kouros
authors.initials: K
authors.lastname: Nouri-Mahdavi
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014794:Visual Fields
keywords: RNFL; disc-fovea angle; glaucoma; spectral-domain OCT; variability