Netzhautgef�szschattenfigur und Makulachagrin als entoptische Funktionspr�fung

Ehrich, W

doi:10.1007/bf00234354

Cited by 6 publications

(3 citation statements)

References 23 publications

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“…When he described the foveal area as having the appearance of ‘shagreen leather’, v. Helmholz [ 14 ] already considered the possibility that this was due to the activity of individual cones. Ehrich [ 22 ] later estimated that the number of grains corresponds to approximately 1000, which is less than the number of cones in this area. However, when the light source is moved, some grains disappear, while others appear, and hence he concludes that the grains do indeed correspond to the activity of single cones.…”

Section: Discussionmentioning

confidence: 99%

How we perceive our own retina

Kirschfeld

2017

Proc. R. Soc. B.

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Ever since the days of René Descartes, in the seventeenth century, the search for the relationship between subjective perception and neural activity has been an ongoing challenge. In neuroscience, an approach to the problem via the visual system has produced a paradigm using perceptual suppression, changing with time. Cortical areas in which the neural activity was modulated in temporal correlation with this percept could be traced. Although these areas may lead directly to perception, such temporal correlation of neural activity does not suffice as ultimate proof that they actually do so. In this article, I will use a different method to show that, for the perception of our own retina, any brain area leading directly to this perception also needs to represent the retina without distortion. Furthermore, I will demonstrate that the phenomenon of size constancy must be realized in this area.

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Section: Discussionmentioning

confidence: 99%

How we perceive our own retina

Kirschfeld

2017

Proc. R. Soc. B.

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“…These grains prompted v. Helmholtz 14 to describe this area as having the appearance of ''shagreen leather.'' By estimating the grain size, Ehrich 15 came to the conclusion that each grain could correspond to the activity of a single cone. If the LED-lamp is moved, the grainy area can be seen to move in relation to the vessels.…”

Section: Do Whole Müller Cells Act As Optical Fibers?mentioning

confidence: 99%

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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“…Cologne. noted in 1818 that if light is thrown into the eye at an unusual angle, either obliquely through the cornea or through the sclera, the shadows of the vessels fall upon different set of photoreceptors, so that the vessels become entoptoscopically visible. Moving a small bright light spot from a pen-light over the sclera at a frequency of 2-4 Hz, the foveal capillary network is so clearly visualized by this method as seen in photographs of fluo rescein angiography approximately 30° in diameter (15° meridian) surrounding the cen- tral fovea [2][3]. The subjective findings are, however, always to be accepted with caution, but they are valuable if the patient has considerable intelligence and is a good ob server.…”

Section: Introductionmentioning

confidence: 99%

Retinal Blood Vessel Test in Young-Onset Diabetic Patients

Kluxen¹,

Wilden²

1987

Ophthalmologica

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136 patients with insulin-dependent diabetes mellitus (IDDM) were shown the entoptic blood vessel figure. All patients were examined independently by retinal fluorescein angiography and ophthalmoscopy. 34 patients had no retinopathy, none of them believed to see alterations. 102 patients had different phases of diabetic retinopathy. If there were 1–5 microaneurysms within the 15° meridian surrounding the central fovea, 55% of the patients were able to detect their alterations. If there were 6–20 microaneurysms, 77% of the patients were able to diagnose them. 90% of the patients with an even more severe retinopathy could see their abnormalities. Obviously there are no incorrectly positive results. For intelligent and well-observing patients with IDDM the retinal blood vessel test is a useful method for early detection and self control of diabetic retinopathy. Nevertheless, control of the fundus by an ophthalmologist is still necessary.

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Netzhautgef�szschattenfigur und Makulachagrin als entoptische Funktionspr�fung

Cited by 6 publications

References 23 publications

How we perceive our own retina

How we perceive our own retina

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

Retinal Blood Vessel Test in Young-Onset Diabetic Patients

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