The directional sensitivity of the photoreceptors in the human achromat.

Nordby, Knut; Sharpe, Lindsay T.

doi:10.1113/jphysiol.1988.sp017079

Cited by 21 publications

(14 citation statements)

References 38 publications

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“…The function, at retinal level, can also be approximated by a parabolic equation, the average p-value for three subjects being about 0.013 mm À2 . This value corresponds well with the value of p ¼ 0.015 mm À2 determined by Nordby and Sharpe [13] in complete achromatopsia, where rods dominate the functioning of the retina.…”

Section: The Stiles-crawford Effect For Cones and Rodssupporting

confidence: 64%

The virtual pupil

Walraven¹

2009

Journal of Modern Optics

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Stiles and Crawford showed over 75 years ago that the sensitivity of the retina varies with the place of entry of the light into the pupil, and thus with the direction of incidence of light upon the retina. The effect is a property of the cones. Rods have a very limited directional sensitivity with a common centre of symmetry with the photopic SC-function. One reason, amongst others, for the existence of the Stiles-Crawford effect is supposed to be the suppression of stray light in the ocular media. The light from, for example, the sun or the bright sky, will be scattered in the ocular media, and cause a haze over the visual scene, thereby decreasing contrast. Thanks to the Stiles-Crawford effect, this scattered light will not be perceived. In order to judge the weight, with respect to other reasons, of this stray light theory, a quantitative study of the amount of stray light is required. This suggestion is based on indications that the scattering in the ocular media is mainly forward scattering, and that stray light coming from the retina seems not to contribute much either. Indirect evidence in favour of the stray light hypothesis is that in nighttime conditions, the visual surround is dark, disturbing stray light does not exist, and the rods therefore do not need directional sensitivity. This is indeed the case, and therefore the pupil size is fully used for the few incoming light quanta. At mesopic levels, the disturbing effects of a large pupil, such as spherical and chromatic aberrations, will be limited for the cones by their directional sensitivity, in the same way as a small pupil does at high luminance levels. It is therefore proposed to consider the directional sensitivity of cones as a virtual pupil.

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Section: The Stiles-crawford Effect For Cones and Rodssupporting

confidence: 64%

The virtual pupil

Walraven¹

2009

Journal of Modern Optics

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“…Light entering the eye near the edge of a dilated pupil is less effective in stimulating the cones than light entering through the center of the pupil because of the Stiles-Crawford effect (Stiles, 1962). The directional sensitivity of the cones is described by a Gaussian profile (Nordby and Sharpe, 1988; Stiles, 1962). Paupoo et al (Paupoo et al, 2000) integrated this profile and determined that for a dilated pupil in an adult, retinal illuminance could be calculated using an effective pupil area of 21 mm 2 rather than the entire area of the dilated pupil which is 50 mm 2 ; that is, a proportion of 0.42.…”

Section: Stimulus Specificationmentioning

confidence: 99%

The neural retina in retinopathy of prematurity

Hansen

Moskowitz

Akula

et al. 2017

Progress in Retinal and Eye Research

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Retinopathy of prematurity (ROP) is a neurovascular disease that affects prematurely born infants and is known to have significant long term effects on vision. We conducted the studies described herein not only to learn more about vision but also about the pathogenesis of ROP. The coincidence of ROP onset and rapid developmental elongation of the rod photoreceptor outer segments motivated us to consider the role of the rods in this disease. We used noninvasive electroretinographic (ERG), psychophysical, and retinal imaging procedures to study the function and structure of the neurosensory retina. Rod photoreceptor and post-receptor responses are significantly altered years after the preterm days during which ROP is an active disease. The alterations include persistent rod dysfunction, and evidence of compensatory remodeling of the post-receptor retina is found in ERG responses to full-field stimuli and in psychophysical thresholds that probe small retinal regions. In the central retina, both Mild and Severe ROP delay maturation of parafoveal scotopic thresholds and are associated with attenuation of cone mediated multifocal ERG responses, significant thickening of post-receptor retinal laminae, and dysmorphic cone photoreceptors. These results have implications for vision and control of eye growth and refractive development and suggest future research directions. These results also lead to a proposal for noninvasive management using light that may add to the currently invasive therapeutic armamentarium against ROP.

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“…Rods have been shown to be less effective waveguides than cones 44–46. This fact, combined with their small diameter (~2 microns),47 likely accounts for the lack of widespread rod imaging.…”

Section: Applicationsmentioning

confidence: 99%

Adaptive Optics Retinal Imaging: Emerging Clinical Applications

Godara¹,

Dubis

Roorda³

et al. 2010

Optometry and Vision Science

151

101

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The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy (SLO) and spectral domain optical coherence tomography (SD-OCT) provide clinicians with remarkably clear pictures of the living retina. While the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, these same optics induce significant aberrations that in most cases obviate cellular-resolution imaging. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. Applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, RPE cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here we review some of the advances made possible with AO imaging of the human retina, and discuss applications and future prospects for clinical imaging.

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The directional sensitivity of the photoreceptors in the human achromat.

Cited by 21 publications

References 38 publications

The virtual pupil

The virtual pupil

The neural retina in retinopathy of prematurity

Adaptive Optics Retinal Imaging: Emerging Clinical Applications

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