[Improved reproducibility of computer-assisted structural analysis of the optic papilla]

Longitudinal monitoring of the optic disc structure by means of automated nervehead analysis (Optic Nerve Head Analyzer, ONHA) can facilitate the diagnosis of ongoing glaucoma. Until recently, however, longitudinal disc monitoring was complicated by considerable fluctuations of the results measured with the Optic Nerve Head Analyzer. Since March/1990 there is a new software version of the equipment (ONHA-plus). The determination of disc parameters using ONHA-plus proved to be significantly more reliable than the determination using the former ONHA: the mean fluctuation of the neuroretinal rim area measured on 18 normal eyes was 0.07 mm2 (ONHA-plus) compared to 0.094 mm2 (ONHA); the variation coefficient dropped from 7.9% (ONHA) to 4.6% (ONHA-plus). A further improvement of the reproducibility can be obtained by double examinations, because the mean examination time using ONHA-plus is about half as long as the examination time using ONHA. Moreover, ONHA-plus enables the recognition and elimination of unreliable results caused by poor image quality. Due to this increased reliability the ONHA-plus system is a considerably improved equipment for the clinical monitoring of glaucoma patients.