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Helge Martin Sudkamp, Dierck Hillmann, Peter Koch, Claus von der Burchard, Malte vom Endt, Michael Münst, Reginald Birngruber, Johann Roider, Gereon Huttmann; Aberration corrected in vivo imaging of the retinal cone mosaic using a simple, full-field OCT approach. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4601.
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© ARVO (1962-2015); The Authors (2016-present)
Imaging the retinal cone mosaic requires the correction of aberrations caused by imperfections of the eye. This correction is possible by adaptive optics, which is technically challenging and requires complex and expensive devices. Recently, numerical approaches for correcting aberrations in post processing were presented, which however require data with undisturbed phase information. This is currently not possible with commercially available OCT systems since high imaging speed is needed to avoid the influence of motion to the phase of the OCT signal. Here, we use a simple FF-OCT, which delivers motion-free phase information from enface plane to correct for aberrations in numerical post processing.
We imaged the human retina using off-axis full-field time-domain (OA-FF-TD) OCT. The system used consists of only a few relatively inexpensive optical components and allows to build a handheld OCT device capable of imaging the human retina in vivo.Images were recorded at 6 mm pupil size from healthy volunteers. An iterative computational algorithm was applied to the data to determine and correct for ocular aberrations.
We acquired images with a field of view of 1.6 mm x 0.7 mm for various retinal regions of healthy subjects. After numerically correcting for aberrations, we were able to resolve the cone mosaic above an eccentricity of 3° temporal to the fovea. From this data we were also able to determine the spacing of the regular cone mosaic. For eccentricities of 4°, 6.5°, 8° and 9° we determined an average cone density of 16 000, 12 000, 10 000, and 8000 cones per mm2 in a healthy subject.
OA-FF-TD-OCT is a promising new technology, for a simple and robust retina scanner system. In contrast to commercially available OCT systems, it allows for aberration free imaging of the human retina at large pupil sizes and thus is able to resolve single cells of the cone mosaic.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Cone mosaic 8 degree temporal of to the fovea before aberration correction. The field of view is 5 degree times 2 degree
Cone mosaic 8 degree temporal of to the fovea after aberration correction. The field of view is 5 degree times 2 degree
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