Volumetric integration model of the Stiles-Crawford effect of the first kind and its experimental verification

Vohnsen, Brian; Carmichael, Alessandra; Sharmin, Najnin; Qaysi, Salihah; Valente, Denise

doi:10.1167/17.12.18

Cited by 21 publications

(32 citation statements)

References 47 publications

(58 reference statements)

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“…23 A ''Volumetric integration model of the Stiles-Crawford effect of the first kind and its experimental verification'' was therefore developed. 24 However, in this model too, the outer segments, and not the Müller cells, are responsible for the generation of the SC1 effect.…”

Section: Do Portions Of Müller Cells Act As Optical Fibers?mentioning

confidence: 84%

Do Müller Cells Act as Optical Fibers in the Primate Retina?

Kirschfeld

2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To examine whether Müller cells in the primate retina act as optical light guides. METHOD. In the literature, it has been suggested that Müller cells in the primate retina act as optical fibers. I have conducted a survey of the literature for papers in support of or refuting this assumption. RESULTS. I show that neither histology, nor the direct observation of photoreceptors, nor the entoptic observation of the retina agree with the assumption that Müller cells in the human retina act as optical waveguides. CONCLUSIONS. I confirm the classic view that the inner/outer segments act together as optical waveguides and that they are the origin of the Stiles-Crawford effect of the first kind.

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Section: Do Portions Of Müller Cells Act As Optical Fibers?mentioning

confidence: 84%

Do Müller Cells Act as Optical Fibers in the Primate Retina?

Kirschfeld

2019

Invest. Ophthalmol. Vis. Sci.

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“…In turn, scotopic vision shows a lack of directionality [5,7] despite of the fact that rods are similar in shape to foveal cones. Together, these findings show that the shape of individual photoreceptors does not provide a satisfactory explanation of the SCE-I neither in photopic nor scotopic conditions, but rather the density of visual pigments is a possible cause [16,18]. Also, it has been suggested that dynamical phototropism differences between rods and cones might be involved [19].…”

Section: Introductionmentioning

confidence: 88%

“…The peak location of the sensitivity curve determines the pointing direction of cones [2,8] that often has a nasal bias which is more pronounced for myopic eyes [13]. The transition from Maxwellian (point) to Newtonian (normal) view is nontrivial and underestimates the role of the SCE-I in normal vision by up to an order of magnitude as we have recently shown using a mechanical flickering pupil with diameter in the range of 1.4 to 7.4 mm diameter [16] and followingly confirmed by others using a small flickering aperture on a spatial light modulator [17]. Most SCE-I studies have been performed with foveal vision.…”

Section: Introductionmentioning

confidence: 98%

“…Whilst the SCE-I has typically been explained by angular-dependent waveguide coupling [2,20], self-screening has detailed the SCE-II [21,22]. This incompatibility seems to suggest that waveguiding may play less of a role in vision than commonly assumed [16,18] although it may well be a relevant factor in high-resolution photoreceptor imaging [23].…”

Section: Introductionmentioning

confidence: 99%

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Directional light-capture efficiency of the foveal and parafoveal photoreceptors at different luminance levels: an experimental and analytical study

Martins

Vohnsen

2019

Biomed. Opt. Express

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A gradual drop in visibility with obliquely incident light on retinal photoreceptors is namely described by the Stiles-Crawford effect of the first kind and characterized by a directionality parameter. Using a digital micromirror device in a uniaxial flicker system, here we report on variations of this effect with luminance levels, wavelengths within the visible and near-infrared spectrum and retinal regions ranging from the fovea to 7.5° parafoveal. Results show a consistent directionality in mesopic and photopic conditions. Higher directionality is measured for longer wavelengths, and a decrease with retinal eccentricity is observed. Results are discussed in relation to an absorption model for the visual pigments taking the outer-segment packing and thickness of the neural retina into account. Good correspondence is found without enforcing photoreceptor waveguiding.

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“…The latter case allows the system to be uniaxial, and therefore, eliminate unwanted displacements and spectral errors arising between the two paths of the previous system . The authors have recently reported on the use of such a technique for direct analysis of the integrated SCE‐I …”

Section: Introductionmentioning

confidence: 99%

Analysing the impact of myopia on the Stiles‐Crawford effect of the first kind using a digital micromirror device

Martins

Vohnsen

2018

Ophthalmic Physiologic Optic

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Purpose Photoreceptor light acceptance is closely tied to the Stiles‐Crawford effect of the first kind (SCE‐I). Whether the SCE‐I plays a role in myopic development remains unclear although a reduction in directionality has been predicted for high myopia. The purpose of this study is to analyse the relationship between foveal SCE‐I directionality, axial eye length, and defocus for emmetropic subjects wearing ophthalmic trial lenses during psychophysical measurements and for myopic subjects with their natural correction. Method A novel uniaxial flicker system has been implemented making use of a Digital Micromirror Device (DMD) to flicker between a 2.3 visual degrees circular reference and a set of circular test patterns in a monocular Maxwellian view at 0.5 Hz. The brightness of the test is adjusted by the duty cycle of the projected light to an upper limit of 22 727 Hz. The wavelength and bandwidth are set by a tuneable liquid‐crystal filter centred at 550 nm. A total of four measurement series for 11 pupil entrance points have been realized for the right eye of 6 emmetropic and 10 myopic subjects whose pupils were dilated with tropicamide. Five of the emmetropic subjects wore ophthalmic trial lenses in the range of −3 to +9 dioptres to mimic hyperopic to highly myopic vision and resulting visibility plots have been fitted to a Gaussian SCE‐I function. In turn, the myopic subjects wore their natural correction during the analysis of the SCE‐I. All subjects had their axial eye length determined with an ultrasound device. Results A SCE‐I directionality parameter in the range of 0.03 to 0.06/mm2 was found for the emmetropic subjects with corrected vision in fair agreement to values in the literature. The results also revealed a marked reduction in directionality in the range from 16% to 30% with every 3 dioptre increase of simulated myopia, as well as a 10% increased directionality in simulated hyperopic eyes. For both emmetropic and myopic subjects, a decrease in directionality with increase in axial length was found in agreement with theoretical expectations. Conclusion The study confirms a clear link between SCE‐I directionality, uncorrected defocus, and axial eye length. This may play a role for emmetropization and thus myopic progression as cone photoreceptors capture light from a wider pupil area in elongated eyes due to a geometrical scaling.

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Volumetric integration model of the Stiles-Crawford effect of the first kind and its experimental verification

Cited by 21 publications

References 47 publications

Do Müller Cells Act as Optical Fibers in the Primate Retina?

Do Müller Cells Act as Optical Fibers in the Primate Retina?

Directional light-capture efficiency of the foveal and parafoveal photoreceptors at different luminance levels: an experimental and analytical study

Analysing the impact of myopia on the Stiles‐Crawford effect of the first kind using a digital micromirror device

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