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Dan Chun, Jack Grinband, Stanley Chang, Lawrence A. Yannuzzi, K Bailey Freund, Quan V Hoang; Downgaze-Induced Vitreous Chamber Elongation in Highly Myopic Eyes with Staphyloma as Gauged by Magnetic Resonance Imaging. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1870. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Both genetic and environmental factors are thought to contribute to axial elongation in myopia. The elucidation of modifiable environmental factors is critical to slowing myopia progression. Here, we determine if the stress and strain of normal eye movements result in vitreous chamber axial length change in highly myopic eyes.
A prospective imaging study was performed on 82 eyes of 43 highly myopic patients (> 27 mm of axial length on IOLMaster) with a clinical diagnosis of staphyloma. 3D MRI scans were acquired while subjects gazed in 5 directions (primary, nasal, temporal, superior and inferior). Volume renderings were manually segmented to isolate the fluid-filled vitreous and aqueous chambers and a novel processing pipeline was created to automate alignment of the eye and to measure the vitreous chamber axial length for each eye in every gaze. Vitreous chamber length (defined as the distance along the visual axis from the limbal plane to the anterior surface of the retina) at each eccentric gaze was compared to the vitreous chamber length in primary gaze using a fixed effects regression allowing for person-specific and eye-specific effects. To account for the repeated measurements of vitreous chamber length for each subject, we report standard errors that are clustered at the patient-gaze level.
Subjects exhibited a range of ethnic backgrounds, including Caucasian (n = 29), East Asian (n = 9) and African American (n = 5). Axial lengths ranged from 27.0 to 39.3 mm on IOLMaster and vitreous chamber lengths ranged from 20.4 to 33.1 mm (median 24.2) on MRI volumetric renderings. In examining vitreous chamber axial length in the different gazes, we found that the mean change in vitreous chamber length was not statistically significant when comparing primary gaze to nasal (p = 0.35) or temporal gaze (p = 0.52). The mean change in vitreous chamber length was near-zero and not statistically significant when changing from primary gaze to upgaze (p = 0.79, 95% CI -0.03 to 0.04). There was vitreous chamber elongation when changing from primary gaze to downgaze by +0.04 mm (p = 0.026, 95% CI 0.005 to 0.08).
A reversible, instantaneous vitreous chamber axial elongation appears to occur only in downgaze, which is consistent with past clinical studies suggesting an association between excessive near work and myopia development and progression.
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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