Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

Huang, Jinxin; Yuan, Qun; Zhang, Buyun; Xu, Ke; Tankam, Patrice; Clarkson, Eric; Kupinski, Matthew A.; Hindman, Holly B.; Aquavella, James V.; Suleski, Thomas J.; Rolland, Jannick P.

doi:10.1364/boe.5.004374

Cited by 24 publications

(12 citation statements)

References 22 publications

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“…Using a maximum likelihood (ML) approach, Huang et al [40] proposed an algorithm for super-resolved OCT measurement and applied it to an in vitro tear film phantom measurement. To the best of our knowledge, our approach based on measurements of the OCT reflectance to obtain super-resolved thickness maps is new in the OCT field.…”

Section: Discussionmentioning

confidence: 99%

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Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

Santos

Schmetterer²,

Triggs

et al. 2016

Biomed. Opt. Express

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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.

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Section: Discussionmentioning

confidence: 99%

“…Low-pass filtering is physically applied before discretization, because of the finite spectral resolution of the detection [40]. This low-pass filtering leads to a finite depth range [1].…”

Section: A2 Detected Spectral Arraymentioning

confidence: 99%

Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

Santos

Schmetterer²,

Triggs

et al. 2016

Biomed. Opt. Express

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show abstract

“…Finally, computationally intensive emerging methods for thickness estimation using OCT raw spectra may be investigated in the future as a mean to further push accuracy and precision in the estimation of thickness if such capability may be leveraged by manufacturers. 19 The method proposed in this paper yields a precision of 0.2 μm and an accuracy of 0.1 μm based on the microscope cover slip validation experiment, in addition to being automatic and fast (full thickness map is generated in less than one minute after the alignment of the lens to the GD-OCM microscope is performed). 33 Results from the current study also establish a benchmark against which other methods may be compared.…”

Section: Discussionmentioning

confidence: 99%

Optical Assessment of Soft Contact Lens Edge-Thickness

et al. 2016

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Purpose To assess the edge shape of soft contact lenses using Gabor-Domain Optical Coherence Microscopy (GD-OCM) with a 2 μm imaging resolution in three dimensions, and to generate edge-thickness profiles at different distances from the edge tip of soft contact lenses. Methods A high-speed custom-designed GD-OCM system was used to produce 3D images of the edge of an experimental soft contact lens (Bausch + Lomb, Rochester NY) in four different configurations: in air, submerged into water, submerged into saline with contrast agent, and placed onto the cornea of a porcine eyeball. An algorithm to compute the edge-thickness was developed and applied to cross-sectional images. The proposed algorithm includes the accurate detection of the interfaces between the lens and the environment, and the correction of the refraction error. Results The sharply defined edge tip of a soft contact lens was visualized in 3D. Results showed precise thickness measurement of the contact lens edge profile. 50 cross-sectional image frames for each configuration were used to test the robustness of the algorithm in evaluating the edge-thickness at any distance from the edge tip. The precision of the measurements was less than 0.2 μm. Conclusions The results confirmed the ability of GD-OCM to provide high definition images of soft contact lens edges. As a non-destructive, precise, and fast metrology tool for soft contact lens measurement, the integration of GD-OCM in the design and manufacturing of contact lenses will be beneficial for further improvement in edge design and quality control. In the clinical perspective, the in-vivo evaluation of the lens fitted onto the cornea will advance our understanding of how the edge interacts with the ocular surface. The latter will provide insights into the impact of long-term use of contact lenses on the visual performance.

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“…The system layout was detailed in our previous study. 16 In summary, the key components of the system consist of a commercial broadband light source, a custom bandpass filter, and a custom broadband astigmatism-corrected Czerny-Turner spectrometer. 21 The supercontinuum laser (WhiteLase Micro, Fianium) is filtered to operate in the spectral window of 600 to 1000 nm.…”

Section: Customized Optical Coherence Tomography Instrumentationmentioning

confidence: 99%

“…To overcome this limitation, we have recently reported a maximum-likelihood (ML) estimator for the tear film thickness measurement. [16][17][18] The purpose of this study is to benchmark the noise properties of different broadband sources, including supercontinuum, SLD, and swept sources, and to investigate the performance of different sources for a thickness estimation task, with both FFT and ML estimators. For such a purpose, the rest of the paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging

et al. 2015

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Abstract. Thickness estimation is a common task in optical coherence tomography (OCT). This study discusses and quantifies the intensity noise of three commonly used broadband sources, such as a supercontinuum source, a superluminescent diode (SLD), and a swept source. The performance of the three optical sources was evaluated for a thickness estimation task using both the fast Fourier transform (FFT) and maximum-likelihood (ML) estimators. We find that the source intensity noise has less impact on a thickness estimation task compared to the width of the axial point-spread function (PSF) and the trigger jittering noise of a swept source. Findings further show that the FFT estimator yields biased estimates, which can be as large as 10% of the thickness under test in the worst case. The ML estimator is by construction asymptotically unbiased and displays a 10× improvement in precision for both the supercontinuum and SLD sources. The ML estimator also shows the ability to estimate thickness that is at least 10× thinner compared to the FFT estimator. Finally, findings show that a supercontinuum source combined with the ML estimator enables unbiased nanometer-class thickness estimation with nanometer-scale precision.

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Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

Cited by 24 publications

References 22 publications

Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

Optical Assessment of Soft Contact Lens Edge-Thickness

Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging

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