title: Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT.
abstract: In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 - 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume.
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria; Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria.
authors.forename: Valentin Aranha
authors.initials: VA
authors.lastname: Dos Santos
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria; Department of Clinical Pharmacology, Medical University of Vienna, Währinger Gürtel 18-20/6L, 1090 Vienna, Austria; Christian Doppler Laboratory for Ocular Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria.
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
authors.affiliation: Photonics Group, Department of Physics, University of York, York YO10 5DD, UK.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Triggs
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria.
authors.forename: Rainer A
authors.initials: RA
authors.lastname: Leitgeb
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Gröschl
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria.
authors.forename: Alina
authors.initials: A
authors.lastname: Messner
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Währinger Gürtel 18-20/6L, 1090 Vienna, Austria; Christian Doppler Laboratory for Ocular Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria.
authors.forename: Doreen
authors.initials: D
authors.lastname: Schmidl
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Währinger Gürtel 18-20/6L, 1090 Vienna, Austria; Christian Doppler Laboratory for Ocular Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhofer
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria; Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria.
authors.forename: Gerold
authors.initials: G
authors.lastname: Aschinger
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria; Christian Doppler Laboratory for Ocular Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20/4L, 1090 Vienna, Austria.
authors.forename: René M
authors.initials: RM
authors.lastname: Werkmeister
keywords: (170.4470) Ophthalmology; (170.4500) Optical coherence tomography