title: Quantitative differences between the optic nerve head and peripapillary retina in low-tension and high-tension primary open-angle glaucoma.
abstract: OBJECTIVE
  To determine whether quantitative differences in optic nerve topography could be identified between patients having primary open-angle glaucoma with normal intraocular pressure (low-tension primary open-angle glaucoma [LT-POAG]) vs those with elevated intraocular pressure (high-tension primary open-angle glaucoma [HT-POAG]).
  
  
  METHODS
  We attempted to match 31 eyes of 31 patients in the LT-POAG group on a case-by-case basis with comparable eyes of 31 patients with HT-POAG. We used the Heidelberg Retina Tomograph to evaluate the optic nerve head and retinal nerve fiber layer.
  
  
  RESULTS
  Cup areas and cup:disk area ratios were significantly larger (P < .05), whereas rim areas, rim volumes, retinal nerve fiber layer heights, and retinal nerve fiber layer cross-sectional areas were consistently smaller, but not significantly so (P > .05), in the LT-POAG group. The inferior neuroretinal rim area was significantly smaller (P < .05) and the mean deviation of superior arcuate area was significantly greater than the opposite sector in patients with LT-POAG but not in those with HT-POAG. A relationship between localized measurements of the optic nerve head and mean deviation was more apparent in the LT-POAG group than in the HT-POAG group.
  
  
  CONCLUSIONS
  The optic cups were larger in patients with LT-POAG than in those with HT-POAG. Measurements of sectors of the optic disk correlated better with visual field changes in LT-POAG than did global measurements of the whole nerve head, indicating more vulnerability of the optic nerve to focal damage with low intraocular pressure.
authors.affiliation: William and Anna Goldberg Glaucoma Service, Wills Eye Hospital/Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5599, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Eid
authors.forename: G L
authors.initials: GL
authors.lastname: Spaeth
authors.forename: M R
authors.initials: MR
authors.lastname: Moster
authors.forename: J J
authors.initials: JJ
authors.lastname: Augsburger
mesh_terms: D016022:Case-Control Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000150:complications / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007429:Intraocular Pressure; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D009798:Ocular Hypertension / Q000150:complications / Q000473:pathology*; D015814:Ocular Hypotension / Q000150:complications / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009900:Optic Nerve / Q000473:pathology*; D011897:Random Allocation; D012160:Retina / Q000473:pathology*; D012189:Retrospective Studies; D014054:Tomography / Q000379:methods; D014794:Visual Fields