title: Correlation of confocal laser scanning tomography with planimetric photographic measurements of the optic disc in a normal South Indian population: the Vellore Eye Study.
abstract: OBJECTIVE
  To compare the confocal laser tomographic scanning evaluation with photographic measurements of the optic nerve head in a South Indian population.
  
  
  METHODS
  The prospective comparative clinical non-interventional epidemiologic study included 62 subjects (62 eyes) forming a population-based sample, selected randomly. Mean age was 47.2 +/- 8.9 years, mean refractive error measured was -0.17 +/- 1.10 diopter (range, - 4.50 to + 2.50 diopter). Confocal laser scanning tomographic images on Heidelberg Retina Tomograph (HRT) and colour optic disc photographs were morphometrically analysed and compared. Main outcome measures were morphologic optic disc parameters.
  
  
  RESULTS
  The optic disc area measurements were significantly smaller (p < 0.001) in the HRT technique than in the photographic method. In contrast, the HRT as compared to the photographic measurements showed significantly (p < 0.001) larger values for the relative width and relative area of the neuroretinal rim. The differences in measurements between both methods were maximum in the nasal part (p < 0.001) of the optic disc and minimum in the temporal disc region.
  
  
  CONCLUSIONS
  In normal eyes of South Indians, neuroretinal rim measurements by the HRT and expressed as percentage of disc size measurements are significantly larger than rim measurements on disc photographs.
authors.affiliation: Department of Ophthalmology, Christian Medical College, Vellore, Tamil Nadu, India. ravithomas@lvpei.org
authors.forename: Ravi
authors.initials: R
authors.lastname: Thomas
authors.forename: Ronnie
authors.initials: R
authors.lastname: George
authors.forename: Jayapraksh
authors.initials: J
authors.lastname: Muliyil
authors.forename: Jost B
authors.initials: JB
authors.lastname: Jonas
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009898:Optic Disk / Q000033:anatomy & histology*; D010781:Photography; D011446:Prospective Studies; D012016:Reference Values