Peripapillary Vessel Density in Relation to Optic Disc Drusen: A Multimodal Optical Coherence Tomography Study.

BACKGROUND: Optic disc drusen (ODD) are acellular calcified deposits within the optic nerve head known to cause visual field defects. An emerging gold standard for the diagnosis of ODD is enhanced depth imaging optical coherence tomography (EDI-OCT). The presence of ODD affects the adjacent peripapillary vasculature, which can be visualized using OCT angiography (OCTA). This study investigates the association between peripapillary vessel density and anatomical ODD location and volume using a newly developed method of multimodal OCT. METHODS: A case-control study with 16 patients diagnosed with ODD in the period 2008-2017 and 24 healthy controls. All patients and controls had EDI-OCT, OCTA, and demographic data collected. Using EDI-OCT and the medical imaging segmentation tool ITK-SNAP, 3-dimensional (3D) visualization of ODD in patients were created. ODD 3D visualization and corresponding OCTA scans were superimposed, making it possible to correlate ODD volume to the peripapillary vessel density in the corresponding modified Garway-Heath segments of the optic disc. RESULTS: We found that mean peripapillary vessel density across all modified Garway-Heath segments were lower in ODD patients compared with controls with significant reduction of peripapillary vessel density in the superior segment ( P = 0.03) and globally ( P = 0.05). A significant inverse proportionality between ODD volume and peripapillary vessel density in the corresponding segment was seen ( P = 0.002). CONCLUSIONS: We found a reduced peripapillary vessel density in regions with close anatomical proximity to ODD and inverse proportionality between ODD volume and peripapillary vessel density.

Optic Nerve Head Anatomy and Vascular Risk Factors in Patients With Optic Disc Drusen Associated Anterior Ischemic Optic Neuropathy.

PURPOSE: Optic disc drusen (ODD) is an anatomical risk factor for nonarteritic anterior ischemic optic neuropathy (NA-AION). This study aimed to investigate the anatomical and vascular risk factors of patients with ODD-AION (ODD-associated NA-AION) and compare them with similar data from patients with nODD-AION (NA-AION without ODD). DESIGN: Case-control study. METHODS: Thirty-four ODD-AION and 34 nODD-AION patients who had all been systematically optical coherence tomography scanned using a standardized ODD scanning protocol were retrospectively analyzed and compared regarding demographics, vascular risk factors, clinical characteristics, and specific optic nerve head anatomical characteristics. RESULTS: In patients with ODD-AION, the ODD were predominantly deeply located (82%) but with no significant difference in size (52% large, 48% small). When compared with nODD-AION patients, ODD-AION patients were significantly younger at the time of diagnosis (P = .012) and had fewer vascular risk factors (P = .015). The ODD-AION patients had significantly more peripapillary hyperreflective ovoid mass-like structures (PHOMS) (P < .001) and prelaminar hyperreflective lines (P < .001) as well as smaller Bruch's membrane opening diameters (P = .017) compared with nODD-AION patients. No significant differences were found between ODD-AION and nODD-AION patients regarding visual acuity, refraction, lamina cribrosa position, ganglion cell layer volume, or retinal nerve fiber layer thickness. CONCLUSION: In ODD-AION, location of the ODD within the optic nerve head is important, while the size of the ODD is not. The ODD-AION and nODD-AION patients presented with distinctly different vascular risk factors and anatomical characteristics, establishing ODD and potentially also PHOMS as independent risk factors for developing NA-AION.