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Central corneal thickness and correlation to optic disc size: a potential link for susceptibility to glaucoma
  1. M Pakravan1,
  2. A Parsa2,
  3. M Sanagou3,
  4. C F Parsa1
  1. 1Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
  2. 2Department of Medicine, University of California, San Francisco, California, USA
  3. 3Ophthalmology Research Center, Shahid Beheshti Medical University, Tehran, Iran
  1. Correspondence to: Dr C F Parsa Wilmer Ophthalmological Institute, Wilmer 233, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21287-9028, USA; cparsa{at}jhmi.edu

Abstract

Aims: To evaluate a possible relationship between central corneal thickness (CCT) and optic disc area in patients with primary open-angle glaucoma (POAG).

Methods: Patients with POAG underwent eye examination, optic disc imaging with the Heidelberg Retina Tomograph II (HRT II) and ultrasound corneal pachymetry. Exclusion criteria were prior ocular surgery and low-quality HRT II images (HRT standard deviation (SD) >50). Pearson’s correlation coefficients were calculated to assess the associations between CCT and optic disc area.

Results: 212 eyes of 137 patients with POAG were examined. In all, 66 (48%) subjects were women, 104 (76%) were Caucasian, 26 (19%) African-American and 7 (5%) other races. 72 eyes remained after excluding those with prior intraocular surgery and low-quality HRT II images. In a univariate analysis of this group, CCT was inversely correlated with optic disc surface area (Pearson’s correlation coefficient r = −0.284, p = 0.036, n = 72). Mean (SD) disc area was 2 (0.53) mm2 (n = 160). Caucasians had significantly smaller discs (p<0.001) than other races (Caucasian 1.9 (0.47) mm2 (n = 119), African-Americans 2.4 (0.54) mm2 (n = 31), other races 2.3 (0.45) mm2 (n = 10)).

Conclusion: CCT is inversely correlated to optic disc area. Although thicker corneas have been recognised to cause slight overestimation of true intraocular pressure (IOP), they may also indicate the presence of a substantially smaller, and thus more robust, optic nerve head. People with thinner corneas which slightly underestimate the true IOP may also have larger and more deformable optic discs.

  • CCT, central corneal thickness
  • POAG, primary open-angle glaucoma
  • HRT II, Heidelberg Retina Tomograph II

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Footnotes

  • Competing interests: None declared.

  • This work was presented at the XXIIIrd Congress of the European Society of Cataract and Refractive Surgeons, 10 September 2005, Lisbon, Portugal.

  • Published Online First 13 September 2006

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