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Optimization of confocal scanning laser ophthalmoscope design.

LaRocca F, Dhalla AH, Kelly MP, Farsiu S, Izatt JA - J Biomed Opt (2013)

Bottom Line: However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts.We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts.Through an experiment comparing our optimized cSLO design to a commercial cSLO system, we show that our design demonstrates a significant improvement in both image quality and resolution.

View Article: PubMed Central - PubMed

Affiliation: Duke University, Department of Biomedical Engineering, Durham, North Carolina 27708, USA. fl20@duke.edu

ABSTRACT
Confocal scanning laser ophthalmoscopy (cSLO) enables high-resolution and high-contrast imaging of the retina by employing spatial filtering for scattered light rejection. However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts. We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts. We tested the imaging capabilities of our cSLO design with an experimental setup from which we obtained fast and high signal-to-noise ratio (SNR) retinal images. At lower FOVs, we were able to visualize parafoveal cone photoreceptors and nerve fiber bundles even without the use of adaptive optics. Through an experiment comparing our optimized cSLO design to a commercial cSLO system, we show that our design demonstrates a significant improvement in both image quality and resolution.

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Object plane spot diagrams for nine configurations spanning a 20-deg field of view (FOV) square on the Goncharov and Dainty31 model eye’s retina demonstrating near diffraction-limited resolution for the illumination path. The Airy disk radius was 7 μm. The Strehl ratios for the center, top-bottom, left-right, and corner configurations are 0.981, 0.975, 0.944, and 0.674, respectively.
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f4: Object plane spot diagrams for nine configurations spanning a 20-deg field of view (FOV) square on the Goncharov and Dainty31 model eye’s retina demonstrating near diffraction-limited resolution for the illumination path. The Airy disk radius was 7 μm. The Strehl ratios for the center, top-bottom, left-right, and corner configurations are 0.981, 0.975, 0.944, and 0.674, respectively.

Mentions: An overview of the optimized optical design of our cSLO is shown in Fig. 3. Spot diagrams, modulation transfer function plots, and an off-axis PSF plot were determined using a recent eye model from Goncharov and Dainty31 and are shown in Figs. 4, 5(a), and 5(b), respectively. The PSF plot was of a configuration demonstrating the largest FWHM of 7 μm. A fixation target to minimize patient eye motion was inserted by placing a dichroic mirror between the last two sets of lenses before the eye (see Fig. 3) in order to image the fixation pattern displayed by a 1 in. liquid crystal display (LCD) screen onto the retina. The lens closest to the eye was mounted on a knob-adjustable rack-and-pinion linear translator designed to allow for diopters of refraction correction. A photograph of the implemented cSLO design is shown in Fig. 6.


Optimization of confocal scanning laser ophthalmoscope design.

LaRocca F, Dhalla AH, Kelly MP, Farsiu S, Izatt JA - J Biomed Opt (2013)

Object plane spot diagrams for nine configurations spanning a 20-deg field of view (FOV) square on the Goncharov and Dainty31 model eye’s retina demonstrating near diffraction-limited resolution for the illumination path. The Airy disk radius was 7 μm. The Strehl ratios for the center, top-bottom, left-right, and corner configurations are 0.981, 0.975, 0.944, and 0.674, respectively.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3713285&req=5

f4: Object plane spot diagrams for nine configurations spanning a 20-deg field of view (FOV) square on the Goncharov and Dainty31 model eye’s retina demonstrating near diffraction-limited resolution for the illumination path. The Airy disk radius was 7 μm. The Strehl ratios for the center, top-bottom, left-right, and corner configurations are 0.981, 0.975, 0.944, and 0.674, respectively.
Mentions: An overview of the optimized optical design of our cSLO is shown in Fig. 3. Spot diagrams, modulation transfer function plots, and an off-axis PSF plot were determined using a recent eye model from Goncharov and Dainty31 and are shown in Figs. 4, 5(a), and 5(b), respectively. The PSF plot was of a configuration demonstrating the largest FWHM of 7 μm. A fixation target to minimize patient eye motion was inserted by placing a dichroic mirror between the last two sets of lenses before the eye (see Fig. 3) in order to image the fixation pattern displayed by a 1 in. liquid crystal display (LCD) screen onto the retina. The lens closest to the eye was mounted on a knob-adjustable rack-and-pinion linear translator designed to allow for diopters of refraction correction. A photograph of the implemented cSLO design is shown in Fig. 6.

Bottom Line: However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts.We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts.Through an experiment comparing our optimized cSLO design to a commercial cSLO system, we show that our design demonstrates a significant improvement in both image quality and resolution.

View Article: PubMed Central - PubMed

Affiliation: Duke University, Department of Biomedical Engineering, Durham, North Carolina 27708, USA. fl20@duke.edu

ABSTRACT
Confocal scanning laser ophthalmoscopy (cSLO) enables high-resolution and high-contrast imaging of the retina by employing spatial filtering for scattered light rejection. However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts. We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts. We tested the imaging capabilities of our cSLO design with an experimental setup from which we obtained fast and high signal-to-noise ratio (SNR) retinal images. At lower FOVs, we were able to visualize parafoveal cone photoreceptors and nerve fiber bundles even without the use of adaptive optics. Through an experiment comparing our optimized cSLO design to a commercial cSLO system, we show that our design demonstrates a significant improvement in both image quality and resolution.

Show MeSH
Related in: MedlinePlus