The Evolution of Eyes - Redwood Center for Theoretical Neuroscience
... about the distribution of light and dark in the surroundings. However, with only shadowingfrom the pigment cup to restrict the acceptance angle of individual receptors, the resolution is muchtoo poor for the eye to detect predators or prey, or to be involved in pattern recognition or the control of ...
... about the distribution of light and dark in the surroundings. However, with only shadowingfrom the pigment cup to restrict the acceptance angle of individual receptors, the resolution is muchtoo poor for the eye to detect predators or prey, or to be involved in pattern recognition or the control of ...
Introduction to retinal straylight
... This can be determined with visual acuity assessment using a letter chart. But eye media disturbance can do much more harm, because it may cause light scattering, resulting in a veil of straylight over the retinal image. The patient complaints may include hazy vision, increased glare hindrance, loss ...
... This can be determined with visual acuity assessment using a letter chart. But eye media disturbance can do much more harm, because it may cause light scattering, resulting in a veil of straylight over the retinal image. The patient complaints may include hazy vision, increased glare hindrance, loss ...
A Review in Innovation in Ocular Prostheses and Visual Implants
... to the microelectrode’s position by means of applying laser treatment during surgery to improve the performance of the neural prosthesis [13]. Although these findings require further study to enhance the contrast, color vision, other efforts are being made regarding to improve prosthetic capabilitie ...
... to the microelectrode’s position by means of applying laser treatment during surgery to improve the performance of the neural prosthesis [13]. Although these findings require further study to enhance the contrast, color vision, other efforts are being made regarding to improve prosthetic capabilitie ...
Reflections on the tapetum lucidum and eyeshine in
... thought to increase visual capabilities in low light. We explored the eyeshine of the posterior medial eye in eight taxa of pisaurid and lycosid spiders. The taxa included four pisaurids: Dolomedes tenebrosus Hentz 1844, D. triton (Walckenaer 1837), D. scriptus Hentz 1845 and D. vittatus Walckenaer ...
... thought to increase visual capabilities in low light. We explored the eyeshine of the posterior medial eye in eight taxa of pisaurid and lycosid spiders. The taxa included four pisaurids: Dolomedes tenebrosus Hentz 1844, D. triton (Walckenaer 1837), D. scriptus Hentz 1845 and D. vittatus Walckenaer ...
Review of Central and Branch Retinal Vein Occlusions
... 12% of cases without any evidence of iris neovascularization. It is also important to follow patients with non-ischemic CRVO as 34% of initially perfused patients convert ...
... 12% of cases without any evidence of iris neovascularization. It is also important to follow patients with non-ischemic CRVO as 34% of initially perfused patients convert ...
The Head and Neck The Head and Neck
... A visual field is the entire area seen by an eye when it looks at a central point. Fields are conventionally diagrammed on circles from the patient’s point of view. The center of the circle represents the focus of gaze. The circumference is 90° from the line of gaze. Each visual field, shown by the ...
... A visual field is the entire area seen by an eye when it looks at a central point. Fields are conventionally diagrammed on circles from the patient’s point of view. The center of the circle represents the focus of gaze. The circumference is 90° from the line of gaze. Each visual field, shown by the ...
Comparison of Macular Thickness and Volume in Amblyopic
... This condition is secondary to visual deprivation or abnormal ocular interaction and is usually divided into three sub-types: strabismic, anisometropic/ametropic and form deprivation (cataract, ptosis, nystagmus); furthermore, these can co-exist. Functional changes are well documented in amblyopia, ...
... This condition is secondary to visual deprivation or abnormal ocular interaction and is usually divided into three sub-types: strabismic, anisometropic/ametropic and form deprivation (cataract, ptosis, nystagmus); furthermore, these can co-exist. Functional changes are well documented in amblyopia, ...
for Vitreoretinal Surgery in Complex Cases
... e all know that diabetes is an epidemic that will continue to grow. It is estimated that in 2003, 189 million people worldwide had diabetes, and predicted that by 2025, 324 million people will have the disease.1 Proliferative diabetic retinopathy (PDR) is the most common complication of diabetes, on ...
... e all know that diabetes is an epidemic that will continue to grow. It is estimated that in 2003, 189 million people worldwide had diabetes, and predicted that by 2025, 324 million people will have the disease.1 Proliferative diabetic retinopathy (PDR) is the most common complication of diabetes, on ...
Hemi–Descemet Membrane Endothelial Keratoplasty
... may have become the preferred treatment in corneal endothelial dysfunction, and the latest refinement of the procedure, Descemet membrane EK (DMEK), may provide the best and fastest visual recovery. 1-3 There is, however, a significant shortage of donor corneal tissue in many parts of the world.4,5 ...
... may have become the preferred treatment in corneal endothelial dysfunction, and the latest refinement of the procedure, Descemet membrane EK (DMEK), may provide the best and fastest visual recovery. 1-3 There is, however, a significant shortage of donor corneal tissue in many parts of the world.4,5 ...
Corneal Epithelial Cell Culture Model for Pharmaceutical Studies
... isolated rabbit ocular tissues (Chung et al., 1998; Gukasyan et al., 2003; Okabe et al., 2005). Ocular pharmacokinetic studies usually require at least five animals at each time point in every studied drug concentration which means the sacrifice of over 100 rabbits in a typical comparison study of t ...
... isolated rabbit ocular tissues (Chung et al., 1998; Gukasyan et al., 2003; Okabe et al., 2005). Ocular pharmacokinetic studies usually require at least five animals at each time point in every studied drug concentration which means the sacrifice of over 100 rabbits in a typical comparison study of t ...
ARVO 2016 Annual Meeting Abstracts 412 Corneal Epithelium
... the amount and DNA binding activity of Sp1 between the different conditions selected. On the other hand, HCSCs have an increased NFI binding activity and also express an additional band for NFI in Western blot when they were grown in the presence of i3T3. RT-qPCR analyses revealed a strong increase ...
... the amount and DNA binding activity of Sp1 between the different conditions selected. On the other hand, HCSCs have an increased NFI binding activity and also express an additional band for NFI in Western blot when they were grown in the presence of i3T3. RT-qPCR analyses revealed a strong increase ...
3512 Summit ST
... guide describes the correct use and application of the instrumentation of the Summit™ SI OCT posterior fixation system. The Summit™ SI OCT posterior fixation system is a versatile modular system, which delivers unparalleled flexibility by ...
... guide describes the correct use and application of the instrumentation of the Summit™ SI OCT posterior fixation system. The Summit™ SI OCT posterior fixation system is a versatile modular system, which delivers unparalleled flexibility by ...
transconjunctival nonvitrectomizing vitreous surgery versus 25
... was determined from the results of previous studies and our preliminary data to detect, with an alpha of 0.05 and a 90% power (1-tailed), a 0.15 logMAR increase in visual acuity. In each group, the mean values of BCVA, central retinal thickness, and NDUs detected before and at 1, 6, and 12 months af ...
... was determined from the results of previous studies and our preliminary data to detect, with an alpha of 0.05 and a 90% power (1-tailed), a 0.15 logMAR increase in visual acuity. In each group, the mean values of BCVA, central retinal thickness, and NDUs detected before and at 1, 6, and 12 months af ...
Diagnosis and Management of Primary Open Angle Glaucoma
... impairs the retrograde axonal transport of essential neurotrophic factors and in turn triggers apoptosis of the retinal ganglion cell. ...
... impairs the retrograde axonal transport of essential neurotrophic factors and in turn triggers apoptosis of the retinal ganglion cell. ...
Diagnosis and Management of Primary Open Angle Glaucoma
... impairs the retrograde axonal transport of essential neurotrophic factors and in turn triggers apoptosis of the retinal ganglion cell. ...
... impairs the retrograde axonal transport of essential neurotrophic factors and in turn triggers apoptosis of the retinal ganglion cell. ...
Basic Sciences- Primary Open Angle Glaucoma
... impairs the retrograde axonal transport of essential neurotrophic factors and in turn triggers apoptosis of the retinal ganglion cell. ...
... impairs the retrograde axonal transport of essential neurotrophic factors and in turn triggers apoptosis of the retinal ganglion cell. ...
Fluorescein angiography in a horse with optic nerve atrophy
... al. 1998, Walde et al. 1970) were not observed. In this particular case the transmitted fluorescence of the large choroidal vessels due to the fundus albinism made it hard to differentiate the ocular fundus structures. In the literature this is referred to as the ‘choroidal window defect’ in the tap ...
... al. 1998, Walde et al. 1970) were not observed. In this particular case the transmitted fluorescence of the large choroidal vessels due to the fundus albinism made it hard to differentiate the ocular fundus structures. In the literature this is referred to as the ‘choroidal window defect’ in the tap ...
Perfluorocarbon Liquid-Assisted External Drainage in the
... variable-sized areas of retinal pigment epithelial detachment. Fluorescein angiography was our major diagnostic tool owing to previous management which had masked the initial presentation and bullous subretinal fluid which precluded an ophthalmoscopic examination. The manifestation in the contralate ...
... variable-sized areas of retinal pigment epithelial detachment. Fluorescein angiography was our major diagnostic tool owing to previous management which had masked the initial presentation and bullous subretinal fluid which precluded an ophthalmoscopic examination. The manifestation in the contralate ...
Uveal compartmentalization in the hamster eye revealed by
... Intraocular pressures (IOP) ranging from 8.0 to 50.0 mmHg, were maintained for periods of 5 to 25 min and tracer simultaneously administered to the anterior chamber of experimental eyes by one of the following methods: (1) A Tycos model A54 manometer was connected to the tracer-filled infusion cannu ...
... Intraocular pressures (IOP) ranging from 8.0 to 50.0 mmHg, were maintained for periods of 5 to 25 min and tracer simultaneously administered to the anterior chamber of experimental eyes by one of the following methods: (1) A Tycos model A54 manometer was connected to the tracer-filled infusion cannu ...
Features of the Retinotopic Representation in the Visual Wulst of a
... density of retinal ganglion cells and, accordingly, the part of the retinotopic map representing the fovea is larger than parts representing similarly sized areas of the retinal periphery. This is called "foveal overrepresentation" [3,10,11]. Such overrepresentation is in many cases enhanced by diff ...
... density of retinal ganglion cells and, accordingly, the part of the retinotopic map representing the fovea is larger than parts representing similarly sized areas of the retinal periphery. This is called "foveal overrepresentation" [3,10,11]. Such overrepresentation is in many cases enhanced by diff ...
Universitat Autònoma de Barcelona D B
... detected in transgenic retinas at early ages. Gliosis is associated with the loss of essential neuron-supportive functions performed by Müller cells. We found that transgenic retinas showed changes in normal retinal metabolism, such as alterations in the metabolism of glutamate and signs of oxidativ ...
... detected in transgenic retinas at early ages. Gliosis is associated with the loss of essential neuron-supportive functions performed by Müller cells. We found that transgenic retinas showed changes in normal retinal metabolism, such as alterations in the metabolism of glutamate and signs of oxidativ ...
A Guide to the Use of Diagnostic Instruments in Eye
... slightly to the right (25º) of the patient and direct the light beam into the pupil. A red “reflex” should appear as you look through the pupil. 6. Rest your left hand on the patient’s forehead and hold the upper lid of the eye near the eyelashes with the thumb. While the patient is fixating on the ...
... slightly to the right (25º) of the patient and direct the light beam into the pupil. A red “reflex” should appear as you look through the pupil. 6. Rest your left hand on the patient’s forehead and hold the upper lid of the eye near the eyelashes with the thumb. While the patient is fixating on the ...
1. The entry of bacteria through which space could lead to an
... parasympathetic fibers that will eventually travel to the otic ganglion. The tympanic nerve lies on the promontory and creates the tympanic plexus, which gives rise to the lesser petrosal nerve. Given the clinical presentation, the patient must have an infection in the tympanic nerve, tympanic plexu ...
... parasympathetic fibers that will eventually travel to the otic ganglion. The tympanic nerve lies on the promontory and creates the tympanic plexus, which gives rise to the lesser petrosal nerve. Given the clinical presentation, the patient must have an infection in the tympanic nerve, tympanic plexu ...
Nedivi Laboratory at MIT – Neuroscience Research at MIT
... Developmental profile of cpg15 expression To investigate a role for cpg15 in the activity-dependent phase of the development of the rat visual system, in situ hybridizations with a cpg15 probe were conducted on sections through visual structures starting at P10. The lateral geniculate nucleus (LGN), ...
... Developmental profile of cpg15 expression To investigate a role for cpg15 in the activity-dependent phase of the development of the rat visual system, in situ hybridizations with a cpg15 probe were conducted on sections through visual structures starting at P10. The lateral geniculate nucleus (LGN), ...
Wnt/beta-catenin signaling in vertebrate eye development
... (Figure 1E). The migrating neural crest cells inhibit the lens specification, while their ablation results in ectopic lens formation (Bailey et al., 2006). In chick embryos, the neural crest cells secrete multiple TGFβs which activate WNT/β-catenin signaling by inducing WNT2b in the adjacent non-len ...
... (Figure 1E). The migrating neural crest cells inhibit the lens specification, while their ablation results in ectopic lens formation (Bailey et al., 2006). In chick embryos, the neural crest cells secrete multiple TGFβs which activate WNT/β-catenin signaling by inducing WNT2b in the adjacent non-len ...
Photoreceptor cell
A photoreceptor cell is a specialized type of neuron found in the retina that is capable of phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.The two classic photoreceptor cells are rods and cones, each contributing information used by the visual system to form a representation of the visual world, sight. The rods are narrower than the cones and distributed differently across the retina, but the chemical process in each that supports phototransduction is similar. A third class of photoreceptor cells was discovered during the 1990s: the photosensitive ganglion cells. These cells do not contribute to sight directly, but are thought to support circadian rhythms and pupillary reflex.There are major functional differences between the rods and cones. Rods are extremely sensitive, and can be triggered by a single photon. At very low light levels, visual experience is based solely on the rod signal. This explains why colors cannot be seen at low light levels: only one type of photoreceptor cell is active.Cones require significantly brighter light (i.e., a larger numbers of photons) in order to produce a signal. In humans, there are three different types of cone cell, distinguished by their pattern of response to different wavelengths of light. Color experience is calculated from these three distinct signals, perhaps via an opponent process. The three types of cone cell respond (roughly) to light of short, medium, and long wavelengths. Note that, due to the principle of univariance, the firing of the cell depends upon only the number of photons absorbed. The different responses of the three types of cone cells are determined by the likelihoods that their respective photoreceptor proteins will absorb photons of different wavelengths. So, for example, an L cone cell contains a photoreceptor protein that more readily absorbs long wavelengths of light (i.e., more ""red""). Light of a shorter wavelength can also produce the same response, but it must be much brighter to do so.The human retina contains about 120 million rod cells and 6 million cone cells. The number and ratio of rods to cones varies among species, dependent on whether an animal is primarily diurnal or nocturnal. Certain owls, such as the tawny owl, have a tremendous number of rods in their retinae. In addition, there are about 2.4 million to 3 million ganglion cells in the human visual system, the axons of these cells form the 2 optic nerves, 1 to 2% of them photosensitive.The pineal and parapineal glands are photoreceptive in non-mammalian vertebrates, but not in mammals. Birds have photoactive cerebrospinal fluid (CSF)-contacting neurons within the paraventricular organ that respond to light in the absence of input from the eyes or neurotransmitters. Invertebrate photoreceptors in organisms such as insects and molluscs are different in both their morphological organization and their underlying biochemical pathways. Described here are human photoreceptors.