May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Ophthalmic Ultrahigh Resolution Optical Coherence Tomography: Eliminating Chromatic Aberration of the Human Eye
Author Affiliations & Notes
  • A. Unterhuber
    School of Optometry & Vision Science, Cardiff University, Cardiff, United Kingdom
  • B. Povaay
    School of Optometry & Vision Science, Cardiff University, Cardiff, United Kingdom
  • E. J. Fernandez
    Laboratorio de Optica, Universidad de Murcia, Murcia, Spain
  • B. Hermann
    School of Optometry & Vision Science, Cardiff University, Cardiff, United Kingdom
  • B. Hofer
    School of Optometry & Vision Science, Cardiff University, Cardiff, United Kingdom
  • H. Sattmann
    Center for Biomedical Engineering and Physics, Medical University Vienna, Vienna, Austria
  • W. Drexler
    School of Optometry & Vision Science, Cardiff University, Cardiff, United Kingdom
  • Footnotes
    Commercial Relationships A. Unterhuber, None; B. Povaay, None; E.J. Fernandez, None; B. Hermann, None; B. Hofer, None; H. Sattmann, None; W. Drexler, Carl Zeiss Meditec, C.
  • Footnotes
    Support Cardiff University, FP6-IST-NMP-2 STREPT (017128), FWF Y 159-PAT, the Christian Doppler Society, FEMTOLASERS GmbH, Carl Zeiss Meditec Inc., Maxon Computer GmbH
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 4249. doi:
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    • Get Citation

      A. Unterhuber, B. Povaay, E. J. Fernandez, B. Hermann, B. Hofer, H. Sattmann, W. Drexler; Ophthalmic Ultrahigh Resolution Optical Coherence Tomography: Eliminating Chromatic Aberration of the Human Eye. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4249.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose:: To investigate improvements in axial resolution and signal to noise for ultrahigh resolution frequency domain optical coherence tomography (UHR-FD-OCT) using spectral bandwidths exceeding 150 nm.

Methods:: A high speed (up to 25k depth-scans/s) UHR-FD-OCT system has been designed to support 240 nm of spectral bandwidth centred at 800 nm. For illumination a special ultra-broadband Titanium:Sapphire laser based on all chirped specialty mirrors has been set up, emitting 300 nm bandwidth at full width half maximum (FWHM). Chromatic aberrations of the human eye at this wavelength range usually prohibit improvement of axial resolution to levels below 3 µm, which already can be achieved with ~120 nm wide spectral bandwidths. A specially designed optical element has been introduced into the scanning beam path to exactly compensate the chromatic effects of the human eye. The device has been tested in normal human subjects.

Results:: Measurements on healthy retinas reveal for the first time that effective axial resolutions better than 3 µm can be achieved in vivo. Although chromatic aberrations are the main limitation for axial resolution improvement precise compensation of high order dispersion had to be performed. Results achieved with the broadband three-dimensional UHR-FD-OCT system depict an effective axial resolution of ~1 µm giving access to finer morphological detail in addition to sensitivity improvements.

Conclusions:: Chromatic aberration corrected UHR-OCT employing spectral bandwidths larger than 150 nm does not only improve transversal resolution, but also the effective axial resolution and signal to noise. Correct compensation of these effects leads to tomograms with unprecedented microstructural tissue information. Furthermore employing extremely broad bandwidth might allow the extraction of depth resolved spectroscopic information due to the overlap of absorption features of clinically interesting chromophores (i.e. haemoglobin).

Keywords: laser • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optical properties 
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