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Modeling Photo-Bleaching Kinetics to Create High Resolution Maps of Rod Rhodopsin in the Human Retina.

Ehler M, Dobrosotskaya J, Cunningham D, Wong WT, Chew EY, Czaja W, Bonner RF - PLoS ONE (2015)

Bottom Line: We modeled the kinetics of rhodopsin bleaching by applying variational optimization techniques from applied mathematics.The physical model and the numerical analysis with its implementation are outlined in detail.This new technique enables the creation of spatial maps of the retinal rhodopsin and retinal pigment epithelium (RPE) bisretinoid distribution with an ≈ 50μm resolution.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Mathematics, University of Vienna, Vienna, Austria.

ABSTRACT
We introduce and describe a novel non-invasive in-vivo method for mapping local rod rhodopsin distribution in the human retina over a 30-degree field. Our approach is based on analyzing the brightening of detected lipofuscin autofluorescence within small pixel clusters in registered imaging sequences taken with a commercial 488nm confocal scanning laser ophthalmoscope (cSLO) over a 1 minute period. We modeled the kinetics of rhodopsin bleaching by applying variational optimization techniques from applied mathematics. The physical model and the numerical analysis with its implementation are outlined in detail. This new technique enables the creation of spatial maps of the retinal rhodopsin and retinal pigment epithelium (RPE) bisretinoid distribution with an ≈ 50μm resolution.

No MeSH data available.


Related in: MedlinePlus

Rod rhodopsin measurement (II).To derive the final rhodopsin map, we first detect the blood vessels. Instead of a binary vessel mask, we use a gradual interface at vessel borders resulting in a smooth vessel mask as proposed in Eq (22). Inpainting based on Eq (21) was used to remove the retinal blood vessels from the final rhodopsin map leading to a smooth rod rhodopsin map. We show the computed parameter γ, which is the sum of emission and excitation rhodopsin absorbance. Since the emission rhodopsin absorbance (590nm-600nm) is neglible, γ indeed is the rhodopsin absorbance at 488nm. The center of the fovea lacks rhodopsin whose density increases when moving apart from the center. Consistently with the rod distribution described in [8], rod rhodopsin increases most rapidly along the superior vertical meridian and increases least rapidly along the nasal horizontal meridian. Although we do not see a connected hot spot of highest rod rhodopsin density, we observe larger and more connected areas of highest rhodopsin density in the superior retina than in the inferior retina, again, consistent with the rod distribution in [8].(a) cropped rhodopsin map from Fig 6a to be inpainted(b) smooth mask χ used in the spatial consistency forcing term(c) the final output showing the distribution of the rhodopsin optical density γ, i.e., the rhodopsin absorbance at 488nm. Units are suppressed to indicate that we compute its distribution rather than absolute quantitative optical densities as we are not able to validate overall amplitudes due to background in our image sets.(d) horizontal and vertical rhodopsin profiles, averaged over small stripes.
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pone.0131881.g007: Rod rhodopsin measurement (II).To derive the final rhodopsin map, we first detect the blood vessels. Instead of a binary vessel mask, we use a gradual interface at vessel borders resulting in a smooth vessel mask as proposed in Eq (22). Inpainting based on Eq (21) was used to remove the retinal blood vessels from the final rhodopsin map leading to a smooth rod rhodopsin map. We show the computed parameter γ, which is the sum of emission and excitation rhodopsin absorbance. Since the emission rhodopsin absorbance (590nm-600nm) is neglible, γ indeed is the rhodopsin absorbance at 488nm. The center of the fovea lacks rhodopsin whose density increases when moving apart from the center. Consistently with the rod distribution described in [8], rod rhodopsin increases most rapidly along the superior vertical meridian and increases least rapidly along the nasal horizontal meridian. Although we do not see a connected hot spot of highest rod rhodopsin density, we observe larger and more connected areas of highest rhodopsin density in the superior retina than in the inferior retina, again, consistent with the rod distribution in [8].(a) cropped rhodopsin map from Fig 6a to be inpainted(b) smooth mask χ used in the spatial consistency forcing term(c) the final output showing the distribution of the rhodopsin optical density γ, i.e., the rhodopsin absorbance at 488nm. Units are suppressed to indicate that we compute its distribution rather than absolute quantitative optical densities as we are not able to validate overall amplitudes due to background in our image sets.(d) horizontal and vertical rhodopsin profiles, averaged over small stripes.

Mentions: We inpaint the blood vessels to obtain the final rod rhodopsin map in Fig 7. The deviation between the preliminary rhodopsin map and those after image inpainting, assessed away from the mask, are below 5% in the amplitude, and < 1% in the mean-square error.


Modeling Photo-Bleaching Kinetics to Create High Resolution Maps of Rod Rhodopsin in the Human Retina.

Ehler M, Dobrosotskaya J, Cunningham D, Wong WT, Chew EY, Czaja W, Bonner RF - PLoS ONE (2015)

Rod rhodopsin measurement (II).To derive the final rhodopsin map, we first detect the blood vessels. Instead of a binary vessel mask, we use a gradual interface at vessel borders resulting in a smooth vessel mask as proposed in Eq (22). Inpainting based on Eq (21) was used to remove the retinal blood vessels from the final rhodopsin map leading to a smooth rod rhodopsin map. We show the computed parameter γ, which is the sum of emission and excitation rhodopsin absorbance. Since the emission rhodopsin absorbance (590nm-600nm) is neglible, γ indeed is the rhodopsin absorbance at 488nm. The center of the fovea lacks rhodopsin whose density increases when moving apart from the center. Consistently with the rod distribution described in [8], rod rhodopsin increases most rapidly along the superior vertical meridian and increases least rapidly along the nasal horizontal meridian. Although we do not see a connected hot spot of highest rod rhodopsin density, we observe larger and more connected areas of highest rhodopsin density in the superior retina than in the inferior retina, again, consistent with the rod distribution in [8].(a) cropped rhodopsin map from Fig 6a to be inpainted(b) smooth mask χ used in the spatial consistency forcing term(c) the final output showing the distribution of the rhodopsin optical density γ, i.e., the rhodopsin absorbance at 488nm. Units are suppressed to indicate that we compute its distribution rather than absolute quantitative optical densities as we are not able to validate overall amplitudes due to background in our image sets.(d) horizontal and vertical rhodopsin profiles, averaged over small stripes.
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pone.0131881.g007: Rod rhodopsin measurement (II).To derive the final rhodopsin map, we first detect the blood vessels. Instead of a binary vessel mask, we use a gradual interface at vessel borders resulting in a smooth vessel mask as proposed in Eq (22). Inpainting based on Eq (21) was used to remove the retinal blood vessels from the final rhodopsin map leading to a smooth rod rhodopsin map. We show the computed parameter γ, which is the sum of emission and excitation rhodopsin absorbance. Since the emission rhodopsin absorbance (590nm-600nm) is neglible, γ indeed is the rhodopsin absorbance at 488nm. The center of the fovea lacks rhodopsin whose density increases when moving apart from the center. Consistently with the rod distribution described in [8], rod rhodopsin increases most rapidly along the superior vertical meridian and increases least rapidly along the nasal horizontal meridian. Although we do not see a connected hot spot of highest rod rhodopsin density, we observe larger and more connected areas of highest rhodopsin density in the superior retina than in the inferior retina, again, consistent with the rod distribution in [8].(a) cropped rhodopsin map from Fig 6a to be inpainted(b) smooth mask χ used in the spatial consistency forcing term(c) the final output showing the distribution of the rhodopsin optical density γ, i.e., the rhodopsin absorbance at 488nm. Units are suppressed to indicate that we compute its distribution rather than absolute quantitative optical densities as we are not able to validate overall amplitudes due to background in our image sets.(d) horizontal and vertical rhodopsin profiles, averaged over small stripes.
Mentions: We inpaint the blood vessels to obtain the final rod rhodopsin map in Fig 7. The deviation between the preliminary rhodopsin map and those after image inpainting, assessed away from the mask, are below 5% in the amplitude, and < 1% in the mean-square error.

Bottom Line: We modeled the kinetics of rhodopsin bleaching by applying variational optimization techniques from applied mathematics.The physical model and the numerical analysis with its implementation are outlined in detail.This new technique enables the creation of spatial maps of the retinal rhodopsin and retinal pigment epithelium (RPE) bisretinoid distribution with an ≈ 50μm resolution.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Mathematics, University of Vienna, Vienna, Austria.

ABSTRACT
We introduce and describe a novel non-invasive in-vivo method for mapping local rod rhodopsin distribution in the human retina over a 30-degree field. Our approach is based on analyzing the brightening of detected lipofuscin autofluorescence within small pixel clusters in registered imaging sequences taken with a commercial 488nm confocal scanning laser ophthalmoscope (cSLO) over a 1 minute period. We modeled the kinetics of rhodopsin bleaching by applying variational optimization techniques from applied mathematics. The physical model and the numerical analysis with its implementation are outlined in detail. This new technique enables the creation of spatial maps of the retinal rhodopsin and retinal pigment epithelium (RPE) bisretinoid distribution with an ≈ 50μm resolution.

No MeSH data available.


Related in: MedlinePlus