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Christopher Anderson Clark, Ann E Elsner, Bryan Haggerty, Joel A Papay; Retinal profile asymmetries in myopes and emmetropes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2160.
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© ARVO (1962-2015); The Authors (2016-present)
Previous work has shown that peripheral refractive error asymmetries exist between different locations in the retina and those asymmetries are greater in myopes than emmetropes. This could be due to a number of factors including physical restriction from the optic nerve and differences in optical alignment between the optical/visual axis. The purpose of this study is to investigate the source of asymmetry.
Fifty-six subjects (refractive error +1.50 to -11.15) had a battery of tests performed including axial length, corneal topography, anterior chamber depth, peripheral refraction, peripheral partial coherence interferometry, and SD OCT for retinal thickness. Turning point location (TPL) was classified as the retinal location in degrees where the retinal profile was at a minimum. Angle alpha was measured as the distance from the apex of the corneal topography to the visual axis. Statistics including repeated measures ANOVA were performed with SPSS (IBM, Endicott, NY.)
The TPL was greatest in high myopes with an average displacement of three degrees temporal from the fovea compared to approximately zero degrees for emmetropes (P = 0.045.) No correlation was found in this study between angle alpha and either the TPL or retinal profile asymmetry along the horizontal axis. Asymmetry did increase with refractive error (P = 0.008.) Visual inspection of the SD OCT images showed greater optic nerve head tilt in subjects with higher asymmetries regardless of refractive error.
Retinal profile asymmetries increase with refractive error which is consistent with previously reported data. These asymmetries appear to be largely due to physical constriction by the optic nerve rather than to do optical effects such as angle alpha.<br />
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