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P.J. Harasymowycz, A. Kamdeu–Fansi, M. Chagnon; Normative RADAAR data: A newparameter for HRT–based diagnosis of glaucoma . Invest. Ophthalmol. Vis. Sci. 2004;45(13):5518.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the distribution of rim area to disc area asymmetry ratio (RADAAR) values in a normal population. Methods: Prospective epidemiological study of subjects invloved in a community glaucoma screening project for primary open–angle glaucoma. Patients underwent bilateral frequency doubling perimetry (FDP) and Heidelberg Retina Tomography (HRT). Normals were defined based on function, and had a normal screening FDP test result, with one minimal point being accepted as normal. RADAAR values were then calculated based on stereometric HRT values and correlations with demographic data, cup to disc area ratio (CDAR) differences and mean disc area sizes performed. Results:Eighty–four patients met the eligibility criteria. RADAAR values varied between 0.75 and 1.45 with a mean of 1.04 (SD 0.110). There was no correlation with age, or sex. Black patients (n=20), however, had significantly higher RADAAR values than Caucasians (n=64); (1.08 vs 1.02; p<0.021). No correlation between RADAAR and mean disc area was found. RADAAR demonstrated a quadrantic and non–linear correlation with CDAR differences (F=62.45, p<0.001), with both lower and higher RADAAR values being associated with larger CDAR differences. Conclusions: RADAAR, a novel HRT–based value, is an indicator of inter–eye rim to disc asymmetry. Blacks may normally exibit more rim to disc asymmetry than than Caucasians. There is a strong and non–linear correlation between cup to disc area ratio differences between eyes and RADAAR, thus knowledge of normative data may help further studies determine whether RADAAR detects early asymmetric glaucoma damage.
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