Assessment of optic nerve head drusen using enhanced depth imaging and swept source optical coherence tomography

Abstract

Background: Optic nerve head drusen (ONHD) are calcific deposits buried or at the surface of the optic disc. Although ONHD may be associated with progressive visual field defects, the mechanism of drusen-related field loss is poorly understood. Methods for detecting and imaging disc drusen include B-scan ultrasonography, fundus autofluorescence, and optical coherence tomography (OCT). These modalities are useful for drusen detection but are limited by low resolution or poor penetration of deep structures. This review was designed to assess the potential role of new OCT technologies in imaging ONHD.

Evidence acquisition: Critical appraisal of published literature and comparison of new imaging devices to established technology.

Results: The new imaging modalities of enhanced depth imaging optical coherence tomography (EDI-OCT) and swept source optical coherence tomography (SS-OCT) are able to provide unprecedented in vivo detail of ONHD. Using these devices it is now possible to quantify optic disc drusen dimensions and assess integrity of neighboring retinal structures, including the retinal nerve fiber layer.

Conclusions: EDI-OCT and SS-OCT have the potential to allow better detection of longitudinal changes in drusen and neural retina and improve our understanding of drusen-related visual field loss.

FIG. 1

Fundus photograph (A), B-scan ultrasound (B), fundus autofluorescence images (C, E) and enhanced depth imaging optical coherence tomography (EDI-OCT) images (D, F) of left eye of subject with optic nerve head drusen. The green lines shown in the red-free images indicate the direction of the respective EDI-OCT line scans.

FIG. 2

Fundus photograph (A), B-scan ultrasound (B), fundus autofluorescence images (C) and enhanced depth imaging optical coherence tomography (EDI-OCT) (D) of the left eye of subject with optic nerve head drusen. The green line in the red-free image indicates the direction of the EDI-OCT line scan. Superficial (small arrows) and buried drusen (large arrows) are shown.

FIG. 3

Enhanced depth imaging optical coherence tomography images of left eye of a subject with optic nerve head drusen (A), with the borders of the drusen outlined in yellow (B).

FIG. 4

Swept source optical coherence tomography of the left eye of a subject with optic nerve head drusen (A, B). The yellow lines on the red-free images indicate the direction of the enhanced depth imaging optical coherence tomography. The corresponding retinal nerve fiber layer thickness “heat-map” is shown (lower image) (C).