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Seth Bronstein, Shannon Xinnan Wang, Kelsey Evans, Nimesh Bhikhu Patel; The Horizontal Raphe in Structure Function Relationships. Invest. Ophthalmol. Vis. Sci. 2016;57(12):364.
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© ARVO (1962-2015); The Authors (2016-present)
To relate optical coherence tomography (OCT) structure and function from standard automated perimetry, several mapping strategies have been developed. To minimize variability in the structure-function correspondence, maps can be individualized to a specific eye. The purpose of this study was to investigate the relationship between major structural and functional landmarks, namely, the horizontal raphe, Bruch’s membrance opening (BMO) and the blind spot.
20 healthy adults (ages 22 to 49) without history of ocular pathology were recruited. High density OCT scans of both eyes were obtained using overlapping regions in the central 60°, that were subsequently flattened to the inner limiting membrane, montaged, and used to locate the horizontal raphe, fovea, and optic nerve. To locate the borders of the blind spot, subjects wore anaglyph glasses and were asked to respond to red/green static and kinetic Goldmann size II stimuli presented on a LCD display. Optical biometry was used to measure axial length. For data analysis, the size and location of the blind spot, size of the BMO, and BMO to fovea to horizontal raphe angle were used.
The mean blind spot diameter using static perimetry (7.26±0.9°) and kinetic perimetry (8.20±0.7°) were significantly different (p<0.01), but linearly related (R2=0.39, p<0.01). On average, the blind spot was 1.5±0.3° larger than the BMO. There was no relationship between axial length and blind spot size or the distance between fixation and the center of the blind spot (p=0.11). The average horizontal raphe angle (-7.17±2.3°) was similar to that of the location of the blind spot (-6.26±3.6°). Horizontal raphe angles were linearly related to blind spot angles but the two angles from a single subject were significantly different. These differences were minimized when the total angular measure was compared from both eyes of the same subject (slope = 1.01, R2=0.84, p<0.01).
The horizontal raphe angle with the optic nerve head corresponds well with the location of the blind spot. For studies using customized structure-function mapping, it is important to account for head tilt and cyclotorsion.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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