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Robert Allan Sharpe, David Williams, Rupal H Trivedi, Jeffrey Blice; Location of foveola relative to optic nerve head in healthy eyes using spectral domain optical coherence tomography (SD-OCT). Invest. Ophthalmol. Vis. Sci. 2016;57(12):4244.
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© ARVO (1962-2015); The Authors (2016-present)
The location of the foveola is key in evaluating and treating a variety of macular diseases. Few prior investigations have studied location of the fovea relative to the optic nerve head; however, none has employed spectral domain optical coherence tomography (SD-OCT). The precision of this imaging modality provides unprecedented ability to measure the location of the foveola. The purpose of this study is to measure the location of the foveola relative to the optic nerve head using SD-OCT in anatomically normal eyes.
Macular SD-OCTs from a single SPECTRALIS® (Heidelberg Engineering) were analyzed in a retrospective manner. Images were included if the OCT revealed normal anatomy and captured sufficient views of the optic disc. Exclusion criteria included retinal vascular events, diabetic retinopathy and any other process that would cause anatomic distortion. Eyes with early dry age-related macular degeneration were included if drusen not visible on imaging. Basic demographic data were obtained in addition to refractive error, hemoglobin A1c, and ocular diagnoses. Measurements were performed using the Heidelberg Eye Explorer software. Location of foveola was determined by the foveal depression and ellipsoid line contour in conjunction with the foveal light reflex. Distances were measured from the midpoint of the temporal aspect of the optic nerve head.
Fifty eyes from 39 patients were included and had a mean age of 57.4 ± 12.6 years. Mean spherical equivalent was -0.19 ± 0.95 in the 44 phakic eyes. The most common diagnoses were diabetes screening (50%) and fellow eye pathology (32%). Mean A1c was 7.4 ± 1.6%. On SD-OCT imaging, mean distance of foveola from optic disc was 594.4 ± 309.5 μm and 3644.8 ± 212.7 μm for vertical and horizontal axes, respectively. The position of fovea in relation to optic nerve head exhibited higher variance vertically than horizontally. The diagonal distance averaged 3706.9 ± 209 μm with a range of 889 μm. No correlation was observed for foveola position with refractive error in phakic eyes.
Significant variability exists regarding location of the foveola in relation to the optic nerve head in healthy eyes, especially in the vertical meridian. SD-OCT provides better localization of foveola than traditional teachings of a reliable position relative to the optic nerve.
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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