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M. Gora, I. Grulkowski, M. Szkulmowski, B. J. Kaluzny, M. Sylwestrzak, S. Marcos, A. Kowalczyk, M. Wojtkowski; Three Dimensional Anterior Segment Imaging During Accommodation Using High Speed Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5798.
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© ARVO (1962-2015); The Authors (2016-present)
To introduce new tools for measuring and visualizing changes in geometry of anterior segment of human eye during its accommodation. To demonstrate new methods for quantitative determination of radii of curvature and analysis of topography of the cornea and crystalline lens from three-dimensional OCT data.
We constructed a new high speed spectral OCT system providing images with 5-mm axial depth covering the cornea from limbus to limbus, and the entire anterior chamber, or optionally the full area and thickness of the crystalline lens. This instrument can acquire three-dimensional data with a speed up to 130k optical A-scans/sec with 6.9 um axial resolution. Six non-dilated eyes of six subjects (25 to 33 years) without previous history of ocular diseases were examined. A fixation point was moved from near to infinity in the same eye, inducing an accommodative response in the tested eye. This procedure was repeated 10 times for each measured eye. The shape of the anterior corneal surface and anterior and posterior lens surfaces were segmented out from the three-dimensional data. In order to obtain true geometry, the three dimensional ray-tracing was applied.
Three dimensional OCT data enables precise determination of geometrical parameters of the anterior segment like localization of corneal axis and estimation of corneal and lens radii of curvature. Volumetric analysis of dynamic changes in the anterior segment, caused by accommodation, provides quantitative information about changes of the lens curvature, lens position in respect to cornea and lens thickness. Additionally we were able to acquire real-time cross-sectional movies of accommodating lens with the use of high speed OCT system. Such a real-time investigation of the dynamic accommodation in living human eyes had not been reported to date using OCT.
Ultrahigh speed OCT imaging of the entire anterior chamber has been achieved using a new Fourier domain instrument. Volumetric data obtained with this instrument were used for detailed quantitative mapping of lens thickness, corneal curvatures and their changes during accommodation process. New instrumentation and analysis tools promise to enable a wide range of new applications for basic research of mechanical properties of cornea, limbus, iris and lens.
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