Photoreceptor waveguides and effective retinal image quality

Vohnsen, Brian

doi:10.1364/josaa.24.000597

Cited by 54 publications

(46 citation statements)

References 43 publications

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“…An initial light distribution entering the cell was taken as a diffraction pattern from the eye's pupil, which is broadened by corneal aberrations, to create an average Gaussian distribution of B40 mm width 24,25 . Next, the field was propagated down the medium, plane by plane, where every step was of 0.13 mm length.…”

Section: Resultsmentioning

confidence: 99%

Müller cells separate between wavelengths to improve day vision with minimal effect upon night vision

et al. 2014

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Vision starts with the absorption of light by the retinal photoreceptors-cones and rods. However, due to the 'inverted' structure of the retina, the incident light must propagate through reflecting and scattering cellular layers before reaching the photoreceptors. It has been recently suggested that Müller cells function as optical fibres in the retina, transferring light illuminating the retinal surface onto the cone photoreceptors. Here we show that Müller cells are wavelength-dependent wave-guides, concentrating the green-red part of the visible spectrum onto cones and allowing the blue-purple part to leak onto nearby rods. This phenomenon is observed in the isolated retina and explained by a computational model, for the guinea pig and the human parafoveal retina. Therefore, light propagation by Müller cells through the retina can be considered as an integral part of the first step in the visual process, increasing photon absorption by cones while minimally affecting rod-mediated vision.

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Section: Resultsmentioning

confidence: 99%

Müller cells separate between wavelengths to improve day vision with minimal effect upon night vision

et al. 2014

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“…Nevertheless, the investigation of differences in cone reflectance between pathological and healthy retinas is still limited to a few isolated studies [20,21]. In addition, studies have demonstrated that cones in the central retina may vary their sensitivity or pointing direction in order to compensate for the eye's internal aberrations [22] or deterioration in the nearby cone's functionality [23] and that cones in the peripheral retina may vary their pointing direction depending on the position of the center of the illumination pupil [24]. The use of AO Optical Coherence Tomography (OCT) has also provided information on the dependence of the reflectance on depth in the inner cone interfaces, leading for the first time to a 3D characterisation of the cone reflectance [14].…”

Section: Introductionmentioning

confidence: 99%

Understanding the changes of cone reflectance in adaptive optics flood illumination retinal images over three years

Mariotti¹,

Devaney²,

Lombardo³

et al. 2016

Biomed. Opt. Express

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Abstract:Although there is increasing interest in the investigation of cone reflectance variability, little is understood about its characteristics over long time scales. Cone detection and its automation is now becoming a fundamental step in the assessment and monitoring of the health of the retina and in the understanding of the photoreceptor physiology. In this work we provide an insight into the cone reflectance variability over time scales ranging from minutes to three years on the same eye, and for large areas of the retina (≥ 2.0 × 2.0 degrees) at two different retinal eccentricities using a commercial adaptive optics (AO) flood illumination retinal camera. We observed that the difference in reflectance observed in the cones increases with the time separation between the data acquisitions and this may have a negative impact on algorithms attempting to track cones over time. In addition, we determined that displacements of the light source within 0.35 mm of the pupil center, which is the farthest location from the pupil center used by operators of the AO camera to acquire high-quality images of the cone mosaic in clinical studies, does not significantly affect the cone detection and density estimation.

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“…This may be at odds with the current understanding that light is focused at the inner segment entrance for best vision. The optical properties of the inner segment in itself, however, and possible cellular focusing effects [47] may support the image guidance [48] and light concentration towards the outer segment. This volumetric optimization of light overlap with the available pigments suggests that in dim light the best focus is possibly shifted forward towards the first layers of the outer segments by approximate −0.1 diopters.…”

Section: Discussionmentioning

confidence: 98%

Directional sensitivity of the retina: A layered scattering model of outer-segment photoreceptor pigments

Vohnsen

2014

Biomed. Opt. Express

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Photoreceptor outer segments have been modeled as stacked arrays of discs or membrane infoldings containing visual pigments with light-induced dipole moments. Waveguiding has been excluded so fields diffract beyond the physical boundaries of each photoreceptor cell. Optical reciprocity is used to argue for identical radiative and light gathering properties of pigments to model vision. Two models have been introduced: one a macroscopic model that assumes a uniform pigment density across each layer and another microscopic model that includes the spatial location of each pigment molecule within each layer. Both models result in highly similar directionality at the pupil plane which proves to be insensitive to the exact details of the outer-segment packing being predominantly determined by the first and last contributing layers as set by the fraction of bleaching. The versatility of the microscopic model is demonstrated with an array of examples that includes the Stiles-Crawford effect, visibility of a focused beam of light and the role of defocus.

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Photoreceptor waveguides and effective retinal image quality

Cited by 54 publications

References 43 publications

Müller cells separate between wavelengths to improve day vision with minimal effect upon night vision

Müller cells separate between wavelengths to improve day vision with minimal effect upon night vision

Understanding the changes of cone reflectance in adaptive optics flood illumination retinal images over three years

Directional sensitivity of the retina: A layered scattering model of outer-segment photoreceptor pigments

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