Abstract
PurposeTo investigate the effect of eye movement on the optic nerve head (ONH) using swept-source optical coherence tomography (SS-OCT), and to measure the degree of ONH changes.MethodsWe enrolled 52 healthy subjects, 20 to 40 years of age, and performed a prospective observational study. Both ONH and macula were imaged simultaneously using wide volume scan of the SS-OCT in the primary and different gaze positions. Horizontal eye movements were used to obtain OCT images in abducted and adducted eyeball positions. Multilateral 3-dimensional registration was used to process and analyze the images to measure the degree of ONH changes.ResultsThe mean axial length (AXL) was 25.73 ± 1.42mm and the mean spherical equivalents was -4.49 ± 2.94 D (The proportion of high myopia was 39.4%). Significant morphologic changes were observed in the ONH during both abduction and adduction. In abduction, the overall ONH tissues were elevated, and the mean area of elevation was 115,134 ± 9,424 μm2 (p<0.001). In adduction, the mean areas from two perspectives, which were nasal or temporal, and peripapillary tissues or optic nerve cupping were 95,277 ± 73,846 μm2, 34,450 ± 44,948 μm2, -108,652 ± 91,246 μm2, and -30,581 ± 46,249 μm2, respectively. Elevation in abduction (overall, nasal cup segment, and temporal cup segment; R = 0.204, 0.195 and 0.225, p = 0.038, 0.047 and 0.021, respectively) and elevation of nasal peripapillary segments in adduction were positively correlated with AXL (R = 0.346, p<0.001).ConclusionWe found significant morphologic changes in the ONH in both abduction and adduction and these changes were associated with AXL. Considering these morphologic changes as physical properties, it allows a better understanding of the biomechanical characteristics of the ONH.
Highlights
The optic nerve is a paired cranial nerve that transmits all visual information from the retina to the brain.[1, 2] The optic nerve is the main lesion of the optic neuropathies including glaucomatous optic neuropathy and the beginning of this, the optic nerve head (ONH), is a unique part of the central nervous system that can be examined directly with appropriate optical equipment and lenses
We found significant morphologic changes in the ONH in both abduction and adduction and these changes were associated with axial length (AXL)
Optic nerve head changes induced by eye movements physical properties, it allows a better understanding of the biomechanical characteristics of the ONH
Summary
The optic nerve is a paired cranial nerve that transmits all visual information from the retina to the brain.[1, 2] The optic nerve is the main lesion of the optic neuropathies including glaucomatous optic neuropathy and the beginning of this, the optic nerve head (ONH), is a unique part of the central nervous system that can be examined directly with appropriate optical equipment and lenses. The concept that eye movement can cause strain on the optic nerve was suggested in the early 19th century[9], and several recent studies reported the ONH change according to the eye movement using OCT. One group recently has shown that peripapillary tissue deformation occurs during horizontal ductions using OCT in healthy participants, in those with anterior ischemic optic neuropathy, in those with papilledema,[10] and in those with optic ONH drusen.[11] Another study demonstrated that adduction but not abduction was associated with peripapillary tissue displacement.[12] We reported that the volcano-like morphological change occurred in the ONH during abduction in highly myopic patient with phosphenes.[13] Because observing structural changes of the ONH can help to infer the strain on the ONH following eye movement, evaluation of ONH changes is important; as mentioned above, the research remains controversial about the morphologic changes that are induced by the eye movement
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