title: Estimation of the relative amount of hemoglobin in the cup and neuroretinal rim using stereoscopic color fundus images.
abstract: OBJECTIVE
  To calculate the relative amount of hemoglobin (Hb) in sectors of the optic nerve head (ONH) from stereoscopic color fundus images using the Laguna ONhE method and compare the results with the visual field evaluation and optical coherence tomography (OCT).
  
  
  METHODS
  Healthy eyes (n = 87) and glaucoma eyes (n = 71) underwent reliable Oculus Spark perimetry and Cirrus OCT. Optical nerve head color images were acquired with a nonmydriatic stereoscopic Wx Kowa fundus camera. Laguna ONhE program was applied to these images to calculate the relative Hb amount in the cup and six sectors of the rim. Receiver operating characteristic (ROC) analysis and correlations between parameters were calculated.
  
  
  RESULTS
  We did not observe any variations in the relative amount of Hb in relation to age in healthy subjects (R(2) = 0.033, P > 0.05). Maximum ROC area confidence intervals were observed for a combination between perimetric indices and the Laguna ONhE Glaucoma discriminant function (0.970-0.899) followed by rim area (0.960-0.883), and mean deviation (MD; 0.944-0.857). In glaucoma cases, relative Hb amount presented significant reduction in all rim sectors, especially 231° to 270° and 81° to 120° (P < 0.001), except in the temporal 311° to 40° (P = 0.11). Perimetry mean sensitivity by sectors was better correlated with respective Hb levels than with rim areas or the corresponding nerve fiber thickness, especially the superior and inferior sectors (P < 0.05).
  
  
  CONCLUSIONS
  Visual field sensitivity was better correlated with Hb levels than with rim sector areas or the corresponding nerve fiber thickness. In many cases the remaining rim show low perfusion, especially in the superior and inferior sectors.
authors: Hospital Universitario de Canarias, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Cristina
authors: C
authors: Pena-Betancor
authors: Hospital Universitario de Canarias, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Marta
authors: M
authors: Gonzalez-Hernandez
authors: Department of Computer Science, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Francisco
authors: F
authors: Fumero-Batista
authors: Department of Computer Science, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Jose
authors: J
authors: Sigut
authors: Hospital Universitario de Canarias, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Erica
authors: E
authors: Medina-Mesa
authors: Department of Computer Science, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Silvia
authors: S
authors: Alayon
authors: Hospital Universitario de Canarias, University of La Laguna, La Laguna, Tenerife, Spain.
authors: Manuel
authors: M
authors: Gonzalez de la Rosa
mesh_terms: D000367:Age Factors; D000368:Aged; D005260:Female; D005654:Fundus Oculi; D005901:Glaucoma / Q000175:diagnosis / Q000503:physiopathology*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D019721:Ophthalmoscopes; D009898:Optic Disk / Q000737:chemistry*; D011446:Prospective Studies; D012016:Reference Values; D012160:Retina / Q000737:chemistry*; D012984:Software; D041623:Tomography, Optical Coherence; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology
chemical_list: D006454:Hemoglobins
keywords: glaucoma; hemoglobin; optic nerve head; perfusion; perimetry; visual field