[Normal values of various papillary parameters and correlation to papillary size]

The Optic Nerve Head Analyzer was used to study the disc parameters--neuroretinal rim area and cup/disc ratio--in 194 eyes of 122 healthy subjects. Both neuroretinal rim area (1.35 +/- 0.35 mm2) and cup/disc ratio (0.5 +/- 0.18) showed a large interindividual variability, i.e., very small values for the neuroretinal rim and very large values in the cup/disc ratio are not only found in glaucomatous but even in healthy eyes. Due to the great variability of disc parameters, a single examination using the Optic Nerve Head Analyzer will presumably not be sufficient to decide whether an individual disc is glaucomatous or normal. Early recognition of glaucoma by means of computerized disc analysis will therefore require follow-up examinations. In accordance with other investigators, we found a highly significant correlation between the neuroretinal rim area and the corresponding disc size (p less than 0.001), i.e., a large disc normally has a large neuroretinal rim. In addition, we also found a significant correlation between the cup/disc ratio and the corresponding disc size (p less than 0.001), i.e., even the relative value of the cup/disc ratio is not independent of disc size. A large disc normally has a large cup/disc ratio. Correlation studies between disc parameters and disc size cannot determine whether the neuroretinal rim area or the cup/disc ratio gives more information about an optic disc. Both parameters, neuroretinal rim area and cup/disc ratio, however, are of equal value concerning the recognition of glaucoma by means of computerized disc analysis, because early diagnosis of glaucoma with this new technique presupposes intraindividual follow-up examinations.