Reproducibility of RTVue Retinal Nerve Fiber Layer Thickness and Optic Disc Measurements and Agreement with Stratus Optical Coherence Tomography Measurements

Abstract

PURPOSE-To evaluate RTVue spectral-domain optical coherence tomography (OCT) (Optovue Inc, Fremont, California, USA) reproducibility and to assess agreement with Stratus time-domain OCT (Carl Zeiss Meditec, Dublin, California, USA) measurements. DESIGN-Observational clinical study.METHODS-Scans were obtained from both eyes of all participants 3 times using the RTVue nerve head map 4-mm diameter protocol and once using Stratus OCT within the same session. RTVue reproducibility and agreement with Stratus OCT were evaluated for retinal nerve fiber layer (RNFL) and optic disc measurements.RESULTS-Thirty healthy participants (60 eyes) and 38 glaucoma patients (76 eyes) were included in the study. RTVue reproducibility was good in both healthy participants and patients. For average RNFL thickness, the intraclass correlation coefficients in healthy eyes and patient eyes were 0.97 whereas for rim area they were 0.97 and 0.96, respectively. The correlation between RTVue and Stratus measurements generally was good, especially for average RNFL thickness (healthy eyes and patient eyes, r 2 = 0.82 and 0.86, respectively) and rim volume (healthy eyes and patient eyes, r 2 = 0.78 and 0.76, respectively). Bland-Altman plots showed good agreement between the instruments, with better agreement for average RNFL thickness (95% limits of agreement in healthy eyes and patient eyes, −8.6 to 12 µm and −5.6 to −14.8 µm, respectively) than optic disc parameters. Cup-to-disc ratio 95% limits of agreement in healthy eyes and patient eyes were −0.3 to 0.4 and −0.2 to 0.3, respectively. Optic disc measurements with RTVue were smaller than those with Stratus OCT (eg, disc area was on average 0.4 mm 2 smaller and rim area was 0.3 mm 2 smaller with RTVue).CONCLUSIONS-Reproducibility of RTVue RNFL and optic disc measurements was excellent in both groups. The level of agreement between RTVue and Stratus measurements suggests that RTVue has the potential to detect glaucomatous structural changes.Optical Coherence Tomography (Oct) is a noninvasive retinal nerve fiber layer (RNFL) and optic disc imaging method that provides micrometer-scale resolution.1 -4 OCT technology has changed considerably in recent years with the incorporation of spectral-domain (SD) imaging that offers significant advantages over the traditional time-domain (TD) OCT techniques. Unlike TD-OCT, SD-OCT uses a stationary reference mirror, and the OCT signal is acquired using a spectrometer as a detector.6 , 7 SD technology currently is capable of an acquisition speed of up to 29,000 A scans per second.8 In addition, SD-OCT offers a higher resolution than TD-OCT2 and can provide a significant reduction in motion artifacts and an increased signal-to-noise ratio compared with TD-OCT.9 , 10 Until very recently, ophthalmic applications of OCT technology were performed exclusively using TD-OCT (Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA). The recently introduced RTVue (Optovue Inc, Fremont, California, USA) is one of several ultra high-speed, high-resolution OCT ...

Diagnostic accuracy of nerve fibre layer, macular thickness and optic disc measurements made with the RTVue-100 optical coherence tomograph to detect glaucoma

“…The RTVue-100 OCT is one of the recently developed Fourier-domain OCT systems that all have several technical advantages compared with the time-domain OCT technology. [1][2][3][4][5][6] Information on the clinical benefits provided by those technical improvements for detection of glaucoma and glaucoma progression, however, is limited. In most diagnostic accuracy studies, a healthy normal group and an age-matched glaucoma group with pre-defined disease severity are compared.…”

“…The working principle of the device has been described in detail elsewhere. [1][2][3][4] In brief, the RTVue-OCT employs a near-infrared lightsource centred at 840 nm, with a 50 nm bandwidth. The normative database for diagnostic classification consists of 861 healthy eyes of mixed ethnicity subjects, with ages ranging between 19 and 82 years.…”

“…5,6,[13][14][15][16][17][18][19][20][21] The RTVue-100 OCT (Optovue Inc., Fremont, CA, USA) is one of the new commercially available Fourier-domain OCT instruments. [1][2][3][4][17][18][19][20][21] Its axial resolution is approximately 5 mm and the scan speed is 26 000 A-scans per second. Thus the speed is 65 times higher than that of the Stratus OCT system, and the resolution is about twice as good as such time-domain OCT instruments.…”

“…[1][2][3][4][5][6] In various studies, [7][8][9][10][11][12] the sensitivity and specificity of the Stratus OCT in detecting early glaucoma has been found to be only moderate to high. OCT instruments employing the Fourier-domain technology have significantly higher resolution and scan speed, improved image segmentation and better measurement reproducibility compared with the timeFdomain OCT. [1][2][3][4][5][6] Though the technology is new, information on the diagnostic accuracy of the different Fourier-domain OCT instruments to detect glaucoma of different severity, is increasing. 5,6,[13][14][15][16][17][18][19][20][21] The RTVue-100 OCT (Optovue Inc., Fremont, CA, USA) is one of the new commercially available Fourier-domain OCT instruments.…”

Effect of pupil dilation on retinal nerve fibre layer thickness measurements and their repeatability with Cirrus HD-OCT

“…[14][15][16][17] This is a mandatory requirement of any instrument designed not only to diagnose, but also to enable a follow-up assessment of possible changes in any measurement. If there is excellent repeatability, with little variance in measurements, then identifying small changes in those measurements over time will be meaningful, as long as one accounts for age-related changes.…”