Deformation of Optic Nerve Head and Peripapillary Tissues By Horizontal Duction

• Published in: American journal of ophthalmology Vol. 174; pp. 85 - 94
• Main Authors: Chang, Melinda Y, Shin, Andrew, Park, Joseph, Nagiel, Aaron, Lalane, Robert A, Schwartz, Steven D, Demer, Joseph L
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2017; Elsevier Limited
• Subjects: Biomechanics; Choroid - diagnostic imaging; Deformation; Eye Movements; Female; Follow-Up Studies; Funding; Glaucoma; Healthy Volunteers; Humans; Male; Medical imaging; Nerve Fibers - pathology; NMR; Nuclear magnetic resonance; Ophthalmology; Optic Disk - diagnostic imaging; Optic nerve; Optic Nerve Diseases - diagnosis; Optics; Prospective Studies; Retinal Ganglion Cells - pathology; Retinal Pigment Epithelium - diagnostic imaging; Scanners; Studies; Tomography; Tomography, Optical Coherence - methods; Young Adult; United States > US; California
• ISSN: 0002-9394; 1879-1891
• DOI: 10.1016/j.ajo.2016.10.001

Purpose To ascertain deformation of the optic nerve head (ONH) and peripapillary tissues caused by horizontal duction. Design Prospective, experimental study. Methods Optical coherence tomography of the ONH region was performed in 23 eyes of twelve normal volunteers in central gaze and increasing (10, 20, and 30°) adduction and abduction. Main outcome measures were changes from central gaze in the configuration of the ONH and peripapillary tissues in eccentric gazes. Results Adduction but not abduction was associated with significant, progressive relative posterior displacement of the temporal peripapillary retinal pigment epithelium (tRPE) from its position in central gaze reaching 49±10 μm in 30° adduction (standard error of mean, p<0.0001). Absolute (anterior or posterior) optic cup displacement (OCD) averaged 41±7 μm in 30° adduction. Linear regression showed significant effect of adduction on absolute OCD (slope 1.09±0.36 μm/degree, p=0.0037). In 20° and 30° adduction, all eyes exhibited significant progressive temporal ONH tilting reaching 3.1±0.4° in 30° adduction (p<0.0001). Abduction was not associated with significant peripapillary RPE displacement, OCD, or ONH tilt. Both nasal and temporal peripapillary choroid averaged 9 to 19 μm thinner in adduction and abduction than in central gaze (p<0.02). Conclusions Adduction temporally tilts and displaces the prelaminar ONH and peripapillary tissues. Both adduction and abduction compress the peripapillary choroid. These effects support MRI and biomechanical evidence that adduction imposes strain on the ONH and peripapillary tissues. Repetitive strain from eye movements over decades might in susceptible individuals lead to optic neuropathies such as normal tension glaucoma.