Detecting glaucoma with RADAAR: the Bridlington Eye Assessment Project.

Abstract

To develop a diagnostic algorithm using rim/disc area asymmetry ratio (RADAAR) to discriminate between normal and glaucomatous eyes using the Heidelberg retina tomograph (HRT). RADAAR was calculated by dividing rim/disc area ratio of the larger disc by that of the smaller disc. RADAAR normal tolerances in each disc sector were generated using 611 population based normal elderly individuals (mean age 72.5 years). Overall status for each individual was equal to the worst disc sector. Sensitivity was assessed in 45 patients with open angle glaucoma. RADAAR variance was significantly greater in glaucoma compared with normality in all disc sectors (p<0.001). Normal RADAAR limits were not dependent on age or sex. Overall, at the 99th percentile limit, the diagnostic algorithm's specificity was 95.1% with a sensitivity of 55.6%. Males with glaucoma showed greater RADAAR variance than females. Corresponding sensitivity of the diagnostic algorithm was 63.0% and 44.4% in males and females respectively, although this difference was not statistically significant (p = 0.43). The RADAAR diagnostic algorithm detected glaucoma with moderate sensitivity but was limited by significant numbers of glaucoma patients with symmetrical optic disc changes. RADAAR may have greater sensitivity in males than in females although this requires confirmation in further studies.