Influence of Software Upgrade on Detection of Localized Nerve Fiber Defects with the RTVue Optical Coherence Tomograph in Glaucoma

Abstract

To investigate the influence of a software version upgrade of the RTVue-100 Fourier-domain optical coherence tomograph (RTVue-OCT) on the detection of localized retinal nerve fiber layer (RNFL) defects in glaucoma. In software version 4.0 of RTVue-OCT 16, 22.5o-sized RNFL sectors are compared to the normative database, respectively, while in the 6.3 version, 8 45o-sized RNFL sectors are investigated and compared to the same normative database. We investigated data of 56 glaucomatous eyes with one or more localized RNFL defects found using software version 4.0, and reanalyzed them using software version 6.3. A corresponding localized visual field defect was seen for all localized RNFL defects. We found 37 RNFL defects which extended to only one 22.5o-sized sector surrounded by an area labeled as within normal limits. Six of them (3 classified as borderline and 3 as outside normal limits by software version 4.0) were classified as within normal limits when they were analyzed with software version 6.3. The other 31 focal RNFL defects and all wider localized RNFL defects which extended to 2 neighboring 22.5o-sized sectors were detected with both software versions. A software upgrade of the RTVue-OCT, which doubles the size and reduces the number of RNFL sectors, decreases the probability of detection of narrow focal RNFL defects in glaucoma. RTVue-OCT users need to know this, and in order to detect localized RNFL thinning in glaucoma they should rely on other features of the report.