Evaluation of retinal nerve fiber layer progression in glaucoma: a comparison between spectral-domain and time-domain...

To compare the performance of a spectral-domain optical coherence tomography (OCT) device and a time-domain OCT device to detect retinal nerve fiber layer (RNFL) progression in glaucoma patients.

Prospective study.

One hundred twenty-eight eyes of 81 glaucoma patients.

Patients were followed up at 4-month intervals for at least 24 months for RNFL imaging and visual field examination. Both eyes were imaged by the Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) and the Stratus OCT (Carl Zeiss Meditec, Inc.) and underwent visual field testing at the same visit. Linear regression analyses between circumpapillary RNFL measurements (average, superior, and inferior RNFL thicknesses), visual field index (VFI), and follow-up time were performed. RNFL progression and RNFL improvement were identified when a significant negative or positive trend was detected, respectively. The agreement between the OCT instruments for progression detection was analyzed with κ statistics.

Number of eyes with RNFL progression and improvement, agreement of progression detection between RNFL measurements and VFI, and rate of change of average RNFL thickness.

Twenty-two eyes (19 patients) and 4 eyes (4 patients) had progression, and 0 and 5 eyes (5 patients) had improvement detected by the Cirrus HD-OCT and the Stratus OCT average RNFL measurements, respectively. The agreement for detection of RNFL progression was poor between the 2 OCT instruments (κ = 0.188, 0.027, and 0.267 for average, superior, and inferior RNFL thicknesses, respectively). The respective agreement between VFI and average RNFL thickness progression determined by the Cirrus HD-OCT and the Stratus OCT was 0.125 and 0.047. The rate of average RNFL thickness progression ranged between -1.52 μm/year and -5.03 μm/year for the Cirrus HD-OCT and between -2.22 μm/year and -7.60 μm/year for the Stratus OCT.

The Cirrus HD-OCT outperformed the Stratus OCT in detecting more eyes with RNFL progression and fewer eyes with RNFL improvement. Because of reduced measurement variability, the Cirrus HD-OCT could detect changes in RNFL thickness sooner than the Stratus OCT.

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