Retinal nerve fiber layer imaging with spectral-domain optical coherence tomography: patterns of retinal nerve fiber layer progression

Abstract

Objective: To examine the use of the retinal nerve fiber layer (RNFL) thickness map generated by a spectral-domain optical coherence tomography (OCT) to detect RNFL progression and identify the pattern of progressive changes of RNFL defects in glaucoma.

Design: Prospective, longitudinal study.

Participants: One hundred eighty-six eyes of 103 glaucoma patients.

Methods: Patients were followed at 4-month intervals for ≥ 36 months for RNFL imaging and visual field examination. Both eyes were imaged by the Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA) and had visual field testing at the same visits. We defined RNFL progression by Guided Progression Analysis (Carl Zeiss Meditec) of serial RNFL thickness maps. The pattern of RNFL progression was evaluated by comparing the baseline RNFL thickness deviation map and the RNFL thickness change map. Visual field progression was defined by trend analysis of visual field index and event analysis based on the Early Manifest Glaucoma Trial criteria.

Main outcome measures: The presence and the pattern of RNFL progression.

Results: A total of 2135 OCT images were reviewed. Twenty-eight eyes (15.1%) from 24 patients (23.3%) had RNFL progression detected by RNFL thickness map analysis. Three RNFL progression patterns were observed: (1) widening of RNFL defects (24 eyes, 85.7%), (2) deepening of RNFL defects (2 eyes, 7.1%, both had concomitant widening of RNFL defects), and (3) development of new RNFL defects (5 eyes, 17.9%). The inferotemporal meridian (324°-336°) 2.0 mm away from the optic disc center was the most frequent location where RNFL progression was detected. Thirteen eyes (46.4%) had concomitant visual field progression; 61.5% (n = 8) of these had RNFL progression that preceded or occurred concurrently with visual field progression. Forty-two eyes from 37 patients (22.6%) had visual field progression by trend and/or event analyses without progression in the RNFL thickness map.

Conclusions: Analysis of serial RNFL thickness maps generated by the spectral-domain OCT facilitates the detection of RNFL progression in glaucoma.