Enhanced depth imaging optical coherence tomography of optic nerve head drusen

Objective: To assess the value of enhanced depth imaging optical coherence tomography (EDI OCT) in diagnosing and evaluating optic nerve head drusen (ONHD) compared with conventional diagnostic methods.

Design: Prospective, comparative, cross-sectional study.

Participants: Thirty-four patients with clinically visible or suspected ONHD in either eye based on dilated optic disc examination or optic disc stereophotography and without ocular comorbidity.

Methods: Spectral-domain OCT of the optic nerve head in both conventional (non-EDI) and EDI modes, ultrasound B-scan, and standard automated perimetry were performed on both eyes of all participants.

Main outcome measures: Detection and findings of ONHD between EDI OCT and conventional diagnostic methods.

Results: Sixty-eight eyes were clinically classified into 3 groups: 32 eyes with definite ONHD, 25 eyes with suspected ONHD, and 11 normal-appearing fellow eyes. In the definite ONHD group, EDI OCT, non-EDI OCT, and ultrasound B-scan were positive for ONHD in all eyes and visual field (VF) was abnormal in 24 eyes. In the suspected ONHD group, EDI OCT, non-EDI OCT, ultrasound B-scan, and VF were positive in 17, 14, 7, and 3 eyes, respectively; 8 eyes had no evidence of ONHD in any of the tests. In normal-appearing fellow eyes, EDI OCT, non-EDI OCT, ultrasound B-scan, and VF were positive in 3, 1, 1, and 0 eyes, respectively; 4 eyes had no evidence of ONHD in any of the tests. Enhanced depth imaging OCT had a significantly higher ONHD detection rate than ultrasound B-scan in all eyes (52/68 eyes vs. 40/68 eyes; P<0.001), in eyes with clinically suspected ONHD or normal-appearing fellow eyes (20/36 eyes vs. 8/36 eyes; P<0.001), and in eyes with clinically suspected ONHD (17/25 eyes vs. 7/25 eyes; P = 0.002). Enhanced depth imaging OCT-detected ONHD appeared as signal-poor regions surrounded by short, hyper-reflective bands or isolated/clustered hyper-reflective bands without a signal-poor core. In non-EDI OCT, posterior surfaces of the ONHD and deep-seated hyper-reflective bands were invisible or less clear than in EDI OCT.

Conclusions: Enhanced depth imaging OCT detects lesions likely representing ONHD more often and better assesses their shape and structure than conventional tests.