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A.S. Neubauer, M. Thiel, U.C. Welge-Luessen, A. Kampik; Comparison of the Retinal Thickness Analyzer (RTA) and the Heidelberg Retina Tomograph (HRT) for Optic Disc Imaging . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3385.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: In the last few years several instruments have become available for optic disc imaging. One of them is the RTA which has been used for retinal imaging for over ten years. The recent generation of the RTA is also capable of three-dimensional image analysis of the optic disc. Reports generated look very similar to those of the HRT, which has been extensively investigated and is widely accepted for disc imaging. The purpose of this study was to compare the results of disc imaging of the RTA and the HRT. Methods: Patients with at least two reliable visual field tests and either ocular hypertension or glaucoma were prospectively included in the study. Stereo optic disc photos, HRT and RTA glaucoma full scans were obtained from all patients. A total of 38 eyes were included in the study. The margin of the optic disc was manually defined on the images obtained with both instruments. Data were compared by student's t-test and correlation coefficients. Results: Of the 12 stereometric parameters obtained from both instruments the disc area, cup area and cup volume differed significantly. Correlation coefficients varied from 0.007 to 0.636. A statistically significant correlation of >0.5 was found for most parameters: mean cup depth, maximum cup depth, cup volume, disc area, rim area and cup area. When larger disc sizes obtained by RTA (mean 3.58 mm2) were adjusted to HRT values (mean 2.61mm2) for each patient, the absolute indices such as cup area, rim area and volume did not differ statistically. Conclusions: The RTA can validly be used to image the optic disc. For most of the parameters RTA and HRT show comparable results. Follow-up should always be performed with the same instrument as the absolute disc size measured with the RTA is usually larger.
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