Purpose/aim of the study: Confocal scanning laser ophthalmoscopy, HRT3, and spectral domain optical coherence tomography (OCT), RTVue-100, are able to give 3-dimensional (3D) topography images of optic nerve head (ONH) and to derive stereometric parameters and sectorial analysis. The purpose of the study is to evaluate the agreement of these two devices and their diagnostic accuracy to discriminate eyes with glaucoma from those without.
Materials and methods: Glaucoma patients and healthy control subjects were included. All of them underwent a complete ophthalmological examination, including slit lamp evaluation and visual field (VF) test. After pupil dilatation, HRT3 and RTVue-100 were performed. The following stereometric parameters were recorded: disc area, rim area, rim volume, cup volume, cup area, cup/disk ratio, and the following sectors, superotemporal, superonasal, inferotemporal, inferonasal.
Results: Forty-six eyes of 46 glaucoma patients and 58 eyes of 58 healthy subjects were included in the study. In both groups, HRT3 rim area and rim volume were statistically higher than RTVue-100 (glaucomas: 0.95 ± 0.38 versus 0.44 ± 0.33 and 0.19 ± 0.13 versus 0.02 ± 0.03, p < 0.01. controls: 1.41 ± 0.30 versus 1.08 ± 0.37 and 0.37 ± 0.13 versus 0.14 ± 0.11, p < 0.01), while cup area was statistically higher by RTVue-100 (glaucomas: 1.42 ± 0.57 versus 1.14 ± 0.58, p < 0.01. controls: 1.05 ± 1.35 versus 0.65 ± 0.48). Bland and Altman plots confirmed the presence of a fixed bias. The parameters with largest AUROC were rim volume, rim area and cup/disk ratio for both instruments. HRT3 inferotemporal sector had the highest sensitivity (80.43%, at 75.9% specificity), while for RTVue-100, the superotemporal sector had the highest sensitivity (76.1%, at 81% specificity). The agreement was moderate for inferotemporal sector and fair for the others.
Conclusions: HRT3 and RTVue-100 are not interchangeable for ONH analysis. They both have good diagnostic accuracy, but RTVue-100 shows slightly better performance, at least with regard to rim area volume.
Keywords: Glaucoma; HRT3; Rtvue-100; imaging; optic nerve head.