Retinal fixation point location in the foveal avascular zone.
... To illustrate, assume that, as in recent clinical trials,6"9 retinal lesions up to 200 ^m from the FAZ center are treated with burns which overlap the lesion by up to 100+ jum. Furthermore, grant that our data form a representative sample of the population for the location of the retinal point of fi ...
... To illustrate, assume that, as in recent clinical trials,6"9 retinal lesions up to 200 ^m from the FAZ center are treated with burns which overlap the lesion by up to 100+ jum. Furthermore, grant that our data form a representative sample of the population for the location of the retinal point of fi ...
Experimental porcine models of retinal ischemia
... The cornea and lens of the eye focus light onto the retina (Figure 1). Light impinging on the photosensitive cells of the retina causes chemical changes that trigger nerve impulses to the brain. The retina in vertebrates has nine layers that originate from the inner wall of the primitive optic cup ( ...
... The cornea and lens of the eye focus light onto the retina (Figure 1). Light impinging on the photosensitive cells of the retina causes chemical changes that trigger nerve impulses to the brain. The retina in vertebrates has nine layers that originate from the inner wall of the primitive optic cup ( ...
Posterior Vitreous Detachment and Its Sequellae
... vitreous may act as a “shock absorber” to prevent dislocation of internal structures such as the lens and iris during severe blunt trauma. Secondly, the high viscosity of the vitreous may prevent excessive anteroposterior movements of the lens-iris diaphragm, thereby stabilizing the eye and maintain ...
... vitreous may act as a “shock absorber” to prevent dislocation of internal structures such as the lens and iris during severe blunt trauma. Secondly, the high viscosity of the vitreous may prevent excessive anteroposterior movements of the lens-iris diaphragm, thereby stabilizing the eye and maintain ...
Visual acuity: the role of visual input in inducing postnatal change
... cones are short, stumpy, and sparsely packed. Their outer segments have small diameters that do not line up well with their wide inner segments. Ideal observer models indicate that newborns' cones are 350 times less ef®cient at capturing light than those in the adult fovea [27]. However, the newborn ...
... cones are short, stumpy, and sparsely packed. Their outer segments have small diameters that do not line up well with their wide inner segments. Ideal observer models indicate that newborns' cones are 350 times less ef®cient at capturing light than those in the adult fovea [27]. However, the newborn ...
Cerebellum
... and aminergic fibers are modified by intracortical circuits formed by three types of interneurons that appear to function as modulators of Purkinje cell activity. These are the Golgi, basket, and stellate cells. Like the Purkinje cells, these interneurons are inhibitory in nature, and they contain the ...
... and aminergic fibers are modified by intracortical circuits formed by three types of interneurons that appear to function as modulators of Purkinje cell activity. These are the Golgi, basket, and stellate cells. Like the Purkinje cells, these interneurons are inhibitory in nature, and they contain the ...
The effects of choroidal or ciliary nerve transection on myopic
... section as carried out by us destroys the fibers distal to the ciliary nerve transections, and choroidal nerve transection as carried out by us does destroy the choroidal nerve fibers distal to the transection. Consequently, we did not seek to confirm the efficacy of the nerve cuts in the present st ...
... section as carried out by us destroys the fibers distal to the ciliary nerve transections, and choroidal nerve transection as carried out by us does destroy the choroidal nerve fibers distal to the transection. Consequently, we did not seek to confirm the efficacy of the nerve cuts in the present st ...
HIGHER STATE EDUCATIONAL INSTITUTION OF UKRAINE
... site of pressure-dependent outflow. The trabecular meshwork functions as a 1-way valve that permits aqueous to leave the eye by bulk flow but limits flow in the other direction, independent of energy. In most older eyes, trabecular cells contain a large number of pigment granules with in their cytop ...
... site of pressure-dependent outflow. The trabecular meshwork functions as a 1-way valve that permits aqueous to leave the eye by bulk flow but limits flow in the other direction, independent of energy. In most older eyes, trabecular cells contain a large number of pigment granules with in their cytop ...
On the cause of disability glare and its dependence on glare angle
... there are four partly-overlapping curves, which are the result of our new analysis. Three of them are for 35-year-olds with three levels of eye pigmentation. They really fan out only in the large angle range, where the lightest eyes have the highest position, that is, most disability glare. Finally, ...
... there are four partly-overlapping curves, which are the result of our new analysis. Three of them are for 35-year-olds with three levels of eye pigmentation. They really fan out only in the large angle range, where the lightest eyes have the highest position, that is, most disability glare. Finally, ...
Retina Retinal Imaging
... number of macular photocoagulation treatments and less reduction in central macular thickness on optical coherence tomography (OCT).14 Sim et al. did not observe this relationship between peripheral ischemia and central macular thickness, but the authors postulate this may have been due to the highe ...
... number of macular photocoagulation treatments and less reduction in central macular thickness on optical coherence tomography (OCT).14 Sim et al. did not observe this relationship between peripheral ischemia and central macular thickness, but the authors postulate this may have been due to the highe ...
1 2. Endoscopic Anatomy of the Paranasal Sinuses Anatomical
... nasolacrimal canal: the canal lies to the lateral nasal wall at the same level as the agger nasi or 1-2 mm in front of it. It runs parallel to the agger, after running medially under some ethmoidal cells. This proximity explains why the lacrimal canal is in danger in the region around the ethmoid ce ...
... nasolacrimal canal: the canal lies to the lateral nasal wall at the same level as the agger nasi or 1-2 mm in front of it. It runs parallel to the agger, after running medially under some ethmoidal cells. This proximity explains why the lacrimal canal is in danger in the region around the ethmoid ce ...
optic disc abnormalities – diagnosis, evolution and influence on
... disc. The condition is caused by an occlusion defect in the embryonic ventral fissure of the optic nerve (, ). Over one-half are positioned temporally on the nerve head, while about one-third are located more centrally on the disc( ,). Optic pits range in size from , to , disc diameters alon ...
... disc. The condition is caused by an occlusion defect in the embryonic ventral fissure of the optic nerve (, ). Over one-half are positioned temporally on the nerve head, while about one-third are located more centrally on the disc( ,). Optic pits range in size from , to , disc diameters alon ...
Study Guide of the Facial Nerve Name the nerve which sends a
... Name the nerve which sends a branch to the tympanic membrane. _____ nerve of ______. The small sensory root of the facial nerve is called nervus intermedius. Name the nucleus which sends visceral motor fibers to the submandibular, sublingual & lacrimal glands. superior salivatory nucleus Name the nu ...
... Name the nerve which sends a branch to the tympanic membrane. _____ nerve of ______. The small sensory root of the facial nerve is called nervus intermedius. Name the nucleus which sends visceral motor fibers to the submandibular, sublingual & lacrimal glands. superior salivatory nucleus Name the nu ...
THE DIAGNOSTIC VALUE OF BIOMICROSCOPY OF THE
... passage of time. The vitreous detachment described (the vitreous detachment with collapse, Hruby), happens suddenly. In cases in which the vitreous had been examined beforehand, it was known that more or less large cavities had already existed before the sudden detachment, and afterwards these holes ...
... passage of time. The vitreous detachment described (the vitreous detachment with collapse, Hruby), happens suddenly. In cases in which the vitreous had been examined beforehand, it was known that more or less large cavities had already existed before the sudden detachment, and afterwards these holes ...
Lysosomes and melanin granules of the retinal pigment
... of Chediak-Higashi patients and several animal models. Affected humans probably have defective digestion in their retinal pigment epithelium also; ivhich could impair the renewal process for rod outer segments. Thus, Chediak-Higashi patients may show an increased susceptibility to light damage due n ...
... of Chediak-Higashi patients and several animal models. Affected humans probably have defective digestion in their retinal pigment epithelium also; ivhich could impair the renewal process for rod outer segments. Thus, Chediak-Higashi patients may show an increased susceptibility to light damage due n ...
Lysosomes and melanin granules of the retinal pigment
... of Chediak-Higashi patients and several animal models. Affected humans probably have defective digestion in their retinal pigment epithelium also; ivhich could impair the renewal process for rod outer segments. Thus, Chediak-Higashi patients may show an increased susceptibility to light damage due n ...
... of Chediak-Higashi patients and several animal models. Affected humans probably have defective digestion in their retinal pigment epithelium also; ivhich could impair the renewal process for rod outer segments. Thus, Chediak-Higashi patients may show an increased susceptibility to light damage due n ...
Optic Disc Swelling (including Papilloedema)
... The time course for the development of papilloedema depends on the cause. It may be weeks if the rise in ICP is slow and mild, but it can occur within a day if the ICP rises suddenly and severely. If there is optic atrophy then there will be little or no papilloedema, even in the presence of raised ...
... The time course for the development of papilloedema depends on the cause. It may be weeks if the rise in ICP is slow and mild, but it can occur within a day if the ICP rises suddenly and severely. If there is optic atrophy then there will be little or no papilloedema, even in the presence of raised ...
Optic Disc Drusen
... (in the third to fourth decades) and that may even recur in a previously affected eye.20 Slowly progressive visual field loss, which is more common in eyes with ODD, is likely a direct effect of the mechanical forces described earlier, which cause axonal dysfunction followed by gradual axonal degene ...
... (in the third to fourth decades) and that may even recur in a previously affected eye.20 Slowly progressive visual field loss, which is more common in eyes with ODD, is likely a direct effect of the mechanical forces described earlier, which cause axonal dysfunction followed by gradual axonal degene ...
Optical Coherence Tomography in Pediatric Ophthalmology: Current
... introduction of new pharmacotherapies for age-related macular degeneration (AMD), and more recently for retinal vascular diseases such as diabetic macular edema (DME), its use has become ubiquitous among retina specialists. In contrast, the use of OCT in pediatric populations has lagged behind that ...
... introduction of new pharmacotherapies for age-related macular degeneration (AMD), and more recently for retinal vascular diseases such as diabetic macular edema (DME), its use has become ubiquitous among retina specialists. In contrast, the use of OCT in pediatric populations has lagged behind that ...
CURRICULUM VITAE - Boston Retinal Implant Project
... I deliver medical care to patients only at the Massachusetts Eye and Ear Infirmary, where I practice as one of three full-time Neuro-Ophthalmologists. I evaluate roughly 40% of all patients referred to our service. My practice is primarily one of diagnostic consultation for a wide range of visual d ...
... I deliver medical care to patients only at the Massachusetts Eye and Ear Infirmary, where I practice as one of three full-time Neuro-Ophthalmologists. I evaluate roughly 40% of all patients referred to our service. My practice is primarily one of diagnostic consultation for a wide range of visual d ...
This article was originally published in the Encyclopedia of the Eye
... applied this concept in their measurements and formulated a disability glare formula, which has been widely used. Nowadays, retinal straylight can also be introduced as the outer skirt of the PSF, outside say, 1 . Since retinal straylight is defined in a functional sense by Leq, the comparison with ...
... applied this concept in their measurements and formulated a disability glare formula, which has been widely used. Nowadays, retinal straylight can also be introduced as the outer skirt of the PSF, outside say, 1 . Since retinal straylight is defined in a functional sense by Leq, the comparison with ...
Pax6 activity in the lens primordium is required for lens formation
... Homozygosity of the Pax6 null mutation in human and mice results in arrest of optic vesicle development and failure to initiate lens formation. This phenotype obscures the understanding of autonomous function of Pax6 in these tissue components and during later developmental stages. We employed the C ...
... Homozygosity of the Pax6 null mutation in human and mice results in arrest of optic vesicle development and failure to initiate lens formation. This phenotype obscures the understanding of autonomous function of Pax6 in these tissue components and during later developmental stages. We employed the C ...
Diabetic Retinopathy Where We Are and A Path to Progress A
... (IRRF) entered into a ten-year collaborative research program on July 15, 2008 entitled the Initiative for Innovation in Vision Science (Initiative). The Initiative is designed to identify knowledge gaps in vision research and develop innovative strategies to advance research on retinal disease. The ...
... (IRRF) entered into a ten-year collaborative research program on July 15, 2008 entitled the Initiative for Innovation in Vision Science (Initiative). The Initiative is designed to identify knowledge gaps in vision research and develop innovative strategies to advance research on retinal disease. The ...
1 Fuchs Endothelial Dystrophy: Pathogenesis and Management
... mutation cosegregated with FED in this pedigree and was absent in 244 ethnically matched control individuals [4]. The COL8A2 gene was sequenced in 115 additional unrelated FED patients, with a total of 8 individuals demonstrating mutations in the COL8A2 gene [4]. Gottsch et al. performed genetic lin ...
... mutation cosegregated with FED in this pedigree and was absent in 244 ethnically matched control individuals [4]. The COL8A2 gene was sequenced in 115 additional unrelated FED patients, with a total of 8 individuals demonstrating mutations in the COL8A2 gene [4]. Gottsch et al. performed genetic lin ...
Effect of Axial Length on Retinal Vascular Network Geometry
... healthy vascular networks, and deviations from this optimal value reflect a less optimized circulatory network. In addition, the angle subtended between two daughter vessels at a vascular junction has also been found to be associated with an optimal value, approximately 75 degrees.6 Thus, these para ...
... healthy vascular networks, and deviations from this optimal value reflect a less optimized circulatory network. In addition, the angle subtended between two daughter vessels at a vascular junction has also been found to be associated with an optimal value, approximately 75 degrees.6 Thus, these para ...
Lutein and Zeaxanthin Isomers in Eye Health and Disease
... assessed in autopsy tissues by high-performance liquid chromatography (19, 30, 31, 33) or by noninvasive assessment of MPOD. A substantial amount of evidence, summarized below, suggests numerous dietary, metabolic, and genetic influences on L and Z absorption, transport in the blood, and accumulatio ...
... assessed in autopsy tissues by high-performance liquid chromatography (19, 30, 31, 33) or by noninvasive assessment of MPOD. A substantial amount of evidence, summarized below, suggests numerous dietary, metabolic, and genetic influences on L and Z absorption, transport in the blood, and accumulatio ...
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.