Optic Nerve Head Topography Analysis in Healthy Adults Using Heidelberg Retina Tomograph and Retinal Thickness Analyzer

Optic nerve head topography analysis using the Heidelberg retina tomograph I (HRT) and the Retinal thickness analyzer (RTA) is important in the early diagnosis and follow up of glau­coma. The aims of our research were to obtain our own database for optic disc topography parameters in normal eyes using HRT and RTA, and assess reproducibility of measurements and clinical agreement between both devices. 50 healthy volunteers underwent HRT and RTA examinations of both eyes. To determine reproducibility of measurements 10 volunteers repea­ted the examinations of left eyes after a week. Differences between measurements by HRT and RTA were tested for statistical significance. Clinical agreement was assessed with lim­its of agreement and reproducibility with repeatability coefficient and intraclass correlation coefficient (ICC). Statistically significant differences (p < 0.05) between measurements by HRT and RTA were observed for all parameters, except for rim area (p = 0.051) and height varia­tion contour (p = 0.054). Limits of agreement were wide and clinically important. Repeatability coefficient was good (< 0.10) for all parameters measured by HRT, except for retinal nerve fibre layer (RNFL) cross-sectional area (0.28). Repeatability coefficient was > 0.10 for cup area (0.15), rim area (0.19), maximum cup depth (0.13), height variation contour (0.11), and RNFL cross-sectional area (0.14) measured by RTA. ICC was good (> 90%) for most parameters, except for mean RNFL thickness (89%) measured by HRT and height variation contour (84%) mea­sured by RTA. The two devices cannot be used interchangeably in clinical practice. At present, clinical usefulness of HRT is superior to RTA.