Glaucoma detection using different Stratus optical coherence tomography protocols

Abstract

To examine and compare the diagnostic accuracy of retinal nerve fibre layer (RNFL) thickness measurements using different Stratus optical coherence tomography (OCT) scanning protocols. Stratus OCT data for 90 healthy subjects and 62 glaucoma patients with mild or moderate visual field loss were prospectively collected and analysed using four RNFL thickness protocols that differed in terms of image resolution and number of scans. Cut-off levels corrected for age and refractive error were defined by reference values derived from an independent normal database. Sensitivity and specificity were calculated for average RNFL thickness for the full circle scan, and for the quadrant and clock hour circle scan sectors at p < 5% and p < 1% cut-off values. Regular- and high-resolution images performed equally well, and single best-quality scans were as good as the average of three scans to distinguish between healthy and glaucomatous eyes. Full circle RNFL thickness yielded similar or better diagnostic accuracy than that of sectors. Sensitivities ranged from 84% to 87% and specificities from 89% to 93% for full circle RNFL thickness at the p < 5% cut-off level. The abilities of four different Stratus OCT RNFL thickness protocols to distinguish between eyes with predominantly mild glaucomatous field loss and healthy eyes were very similar. Thus diagnostic accuracy did not differ between high- and regular-resolution protocols, nor between global (full circle) and localized (sector) OCT parameters, which suggests a diffuse component in early glaucomatous RNFL damage.