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Patrick A Sibony; Gaze-evoked deformations in optic nerve head drusen. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4310.
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We recently described gaze-evoked, “seesaw” deformations of the peripapillary basement membrane-layer(ppBM-layer) in patients with papilledema, ischemic optic neuropathy(AION) and normals.1 The deformations in papilledema were large and presumably due to gaze-induced hydraulic shifts of cerebrospinal fluid against the scleral flange. In AION and normals the deformations were small, temporal to the basement membrane opening(BMO) and presumably due to the tensile tethering of the globe by the optic nerve sheath in adduction.1-3 This study examines the effects of eye position on the shape of the ppBM-layer in patients with optic nerve head drusen(ONHD).
We examined registered 9mm SD-OCT axial-rasters from 20 patients with optic disc drusen . Images were obtained with head rotated so that eyes were positioned at 10-15°adduction and 30-40°abduction. Geometric Morphometric shape analysis, previously described4, 5, was used to analyse the ppBM-layer spanning 2500 microns on each side of the BMO.
There was a statistically significant difference in the shape of the ppBM-layer between abduction and adduction (p=0.01, permutation) characterized by an alternating deformational tilt. On adduction there was a relative posterior displacement of the temporal side with a slight anterior displacement of the nasal side. The reverse pattern occurred in abduction. The magnitude of the deformations in ONHD were similar to those described previously in AION and normals; and substantially smaller than papilledema.
The BMO is a high stress environment. Ocular ductions induce multiple complex modes of strain (i.e. shearing, compression, extension) within and around the ONH that can potentially generate friction between the soft tissues of the ONH (e.g. axons, glial cells, blood vessels, border tissues) and the rigid, sometimes irregular margins of ONHD. The cumulative traumatic effects of repetitive motion from eye movements may be a contributory factor in progressive loss of axons, hemorrhages, vascular occlusions and neovascular membranes that occur in patients with optic nerve head drusen.1. Sibony PA. IOVS 2016;57:4979-4987.2. Demer JL. IOVS 2016;57:1826-1838.3. Wang X, et al. IOVS 2016;57:2452-2462.4. Sibony P, et al. IOVS 2011;52:7987-7995.5. Sibony P, et al. IOVS 2014;55:8223-8231.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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