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Alan Le, Michael Lesgart, Bola Ayoub Gawargious, Soh Youn Suh, Joseph L Demer; Horizontal Duction Causes Age-dependent Deformation of the Optic Nerve Head and Peripapillary Retina. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6173. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether optic nerve tethering during adduction can cause observable deformation of the optic nerve head (ONH) and peripapillary retina (PPR) as reflected by displacement of embedded vascular landmarks in young and older normal subjects.
Right eyes of 20 young adults, age 23.9±3.9 (standard deviation, SD, range 19-32) years, were compared to right eyes of 20 older subjects, age 61.4±9.3 (range 48-79) years. En face images of the ONH and PPR were taken with Heidelberg Spectralis infrared scanning laser ophthalmoscopy in central gaze, 35° abduction, and 35° adduction. Deformations in central versus eccentric gazes of the ONH and adjacent PPR were measured by comparing positions of prominent epipapillary and epiretinal blood vessels (BV) that served as anatomical fiducials.
BVs within the ONH of younger subjects shifted temporally during adduction and nasally during abduction, reflecting deformation of the tissues to which the vessels were attached. Displacement of the nasal half of the ONH in adduction was much greater at 38.5±1.7μm (standard error of the mean, SEM) than in the temporal half at 4.1±2.1μm (P<0.001). In abduction, the temporal half of the young ONH shifted 4.4±0.6μm nasally without significant displacement in the nasal half. This represents horizontal compression of the ONH in adduction more than in abduction. Older subjects showed less temporal shift in the ONH and less PPR displacement within one disc radius (P<0.0001) in adduction. In older subjects, the nasal half of the ONH shifted 24.5±1.3μm compared with 4.4±2.1μm in the temporal half.
Large horizontal duction, particularly adduction, compresses the ONH, and deforms peripapillary vasculature and the underlying neural tissues. This deformation, which is larger in younger than older subjects, may be principally due to optic nerve tethering in adduction.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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