Purpose:
To evaluate the role of Optical Coherence Tomography/Scanning Laser Ophthalmoscopy (OCT/SLO) for optic nerve head drusen (ONHD) imaging with particular focus on determination of morphology within the nerve and its effects on adjacent tissues.
Methods:
Five eyes of three patients with irregular disc margins suspected to have ONHD were selected for the investigation. Glaucoma and other optic neuropathies were excluded by complete ophthalmologic history and examination and automated Humphrey visual field testing. Presence of either visible or buried drusen were confirmed with 20 MHz B-Scan ultrasound. Additional imaging included fundus photography and OCT/SLO (OTI, Toronto, Canada) imaging centered on the optic nerve and peripapillary fibers.
Results:
OCT/SLO, with its unique pixel-to-pixel registration, allowed for greater resolution than existing OCT-imaging techonologies. OCT/SLO of the optic nerves typically demonstrated a lucency created by the buried drusen as well as displacement and thickening of the overlying nerve fiber layer. There was increased reflectivity from the adjacent retinal pigment epithelium. Moreover, the capability of generating three-dimensional topographic maps ensured greater reproducibility for longitudinal follow-up of the same anatomic point at a given depth in the nerve head and retina. This feature offered the potential to answer previously studied questions of ONHD pathophysiology, namely differences between visible and buried drusen, nerve fiber layer damage and temporal progression.
Conclusions:
Optical Coherence Tomography/Scanning Laser Ophthalmoscopy (OCT/SLO) imaging revealed unique, not previously available, and clinically helpful views of optic nerve head drusen.Figure 1. OCT/SLO of the right optic nerve demonstrating the lucency created by the buried drusen as well as displacement and thickening of the overlying nerve fiber layer. There is increased reflectivity from the adjacent retinal pigment epithelium.
Keywords: optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • drusen