Method to reduce undesired multiple fundus scattering effects in double-pass systems

García-Guerra, Carlos Enrique; Martínez‐roda, Joan A; Aldaba, Mikel; Díaz-Doutón, Fernando; Vilaseca, Meritxell; Vohnsen, Brian; Pujol, Jaume

doi:10.1364/josaa.36.000918

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…In this sense, different optical methods have been proposed to reduce IS effects such as Fourier analysis [ 14 ] or adaptive optics ( AO ) deep learning techniques [ 15 ]. However, in the presence of advanced cataracts, corneal distrophies, edema, or vitreous opacifications can lead to an unavoidable VG generation degrading the fundus images and, therefore, making segmentation and image analysis difficult and leading to erroneous estimates.…”

Section: Introductionmentioning

confidence: 99%

Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images

et al. 2021

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The optical quality of an image depends on both the optical properties of the imaging system and the physical properties of the medium in which the light travels from the object to the final imaging sensor. The analysis of the point spread function of the optical system is an objective way to quantify the image degradation. In retinal imaging, the presence of corneal or cristalline lens opacifications spread the light at wide angular distributions. If the mathematical operator that degrades the image is known, the image can be restored through deconvolution methods. In the particular case of retinal imaging, this operator may be unknown (or partially) due to the presence of cataracts, corneal edema, or vitreous opacification. In those cases, blind deconvolution theory provides useful results to restore important spatial information of the image. In this work, a new semi-blind deconvolution method has been developed by training an iterative process with the Glare Spread Function kernel based on the Richardson-Lucy deconvolution algorithm to compensate a veiling glare effect in retinal images due to intraocular straylight. The method was first tested with simulated retinal images generated from a straylight eye model and applied to a real retinal image dataset composed of healthy subjects and patients with glaucoma and diabetic retinopathy. Results showed the capacity of the algorithm to detect and compensate the veiling glare degradation and improving the image sharpness up to 1000% in the case of healthy subjects and up to 700% in the pathological retinal images. This image quality improvement allows performing image segmentation processing with restored hidden spatial information after deconvolution.

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Section: Introductionmentioning

confidence: 99%

Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images

et al. 2021

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Three-dimensional measurement for spherical and nonspherical shapes of contact lenses

Saeki

Huyan

Sawada³

et al. 2021

Appl. Opt.

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In recent years, with the development of precise lathe-cutting equipment, special shaped contact lenses (CL) have been crafted. However, while it is possible to manufacture such a lens, its shape evaluation has not been well-established. We conducted a basic optical experiment using special lenses to measure a spherical lens and nonspherical mold. As the measurement sample, a metal ball, special CL, and a toric-shaped mold were adopted. In order to accurately measure those real shapes, we proposed an algorithm in which the probe light is vertically incident to the sample surface within a numerical aperture of the optical probe. For this algorithm, we developed the specialized time-domain optical coherence tomography (TD-OCT), which was designed to conduct circular scanning while maintaining vertical incidence by driving a two-axis (vertical and horizontal) micro-electromechanical system mirror with a phase difference of 90°. The shape, thickness distribution, and curvature radii of both front and back surfaces of a CL were estimated with this OCT signal analysis and sphere fitting. The shape and curvature radius were evaluated by using the simulated data under the same experimental conditions. They were sufficiently accurate based on the resolution of this OCT. Also, a toric-shaped mold was evaluated by comparing the relationship between each coordinate and intensity of the interference signal. As a result, it is confirmed that the experimental result and the simulated matched well.

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Method to reduce undesired multiple fundus scattering effects in double-pass systems

Cited by 2 publications

References 22 publications

Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images

Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images

Three-dimensional measurement for spherical and nonspherical shapes of contact lenses

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