The optic nerve head was assessed with a confocal scanning laser ophthalmoscope(Heidelberg Retina Tomograph [HRT] II; Heidelberg Engineering GmbH, Heidelberg,Germany). The size of the field of view was 15° × 15°, and digitizationwas performed in frames of 384 × 384 pixels. The spatial resolutionwas 10 µm per pixel. Three 3-dimensional images were obtained for eacheye from each patient. With the HRT II, there is an automatic online qualitycontrol during image acquisition. If 1 or more of the acquired image seriescannot be used for any reason (eg, if the patient were to lose fixation),then additional images are automatically acquired until 3 useful image serieshave been obtained. The mean topographic result of the 3 scan series was usedfor analysis. The contour line was drawn around the optic disc by one of us(P.T.). The standard reference plane was used. There are several approachesthat can be used to discriminate between healthy and glaucomatous optic discs.These approaches rely on global and/or sectorial topographic indices and havesimilar sensitivities.16 We used the Moorfieldsregression analysis approach. It has the advantage of adjusting the globaland sectorial rim areas for disc size and age to improve specificity and toallow for the assessment of regional damage. Regional damage was assessedwith HRT II software by dividing the optic nerve head into 6 sectors (nasal,supranasal, supratemporal, temporal, inferotemporal, and inferonasal). Thesectors were compared with those in a normal database using Moorfields regressionanalysis, and then classified into 1 of 3 categories (within normal limits,borderline, or outside normal limits).17 Briefly,this classification was performed as follows: the rim and disc area for eachsector were compared with those in a normal database, and the sectors werethen classified depending on the patient's age and the overall size of theoptic disc. The analysis provided a predicted value and an actual value forthe rim area of each of the 6 sectors. If the percentage of the rim area fora given sector was larger than or equal to the 95% age-dependent confidencelimit, then the sector was classified as being within normal limits. If thepercentage of rim area was between the 95% and 99.9% confidence limits, thenthe respective sector was classified as borderline. Finally, if the percentageof the rim area for a sector was lower than the 99.9% confidence limit, thenthe sector was classified as being outside normal limits. Only those sectorsclassified as being outside normal limits were included in our mapping analysis.