Fovea Centralis
Tupaiidae
Ganglia, Sensory
Aotidae
Cone Opsins
Cats
Dicrocoelium
Retina
Macula Lutea
Retinal Ganglion Cells
Visual Fields
Cell Count
Photoreceptor Cells
Retinal Rod Photoreceptor Cells
Neurons
Tomography, Optical Coherence
Species Specificity
Retinal Cone Photoreceptor Cells
Visual Acuity
Fundus Oculi
Fluorescein Angiography
Choroid
Retinal Pigments
Raptors
Ophthalmoscopes
Scotoma
Fixation, Ocular
Eagles
Retinoscopy
Moles
Retinal Perforations
Contrast Sensitivity
Scleral Diseases
Photic Stimulation
Photography
Vision, Ocular
Color Vision Defects
Macular Degeneration
Psychophysics
Retinal Diseases
Visual Field Tests
Vision, Entoptic
Myopia, Degenerative
Epiretinal Membrane
Macular Edema
Optic Disk
Photoreceptor Cells, Vertebrate
Lipofuscin
Diagnostic Techniques, Ophthalmological
Vitreous Detachment
Retinal Photoreceptor Cell Inner Segment
Optical, receptoral, and retinal constraints on foveal and peripheral vision in the human neonate. (1/692)
We examined the properties of the foveal, parafoveal, and near peripheral cone lattice in human neonates. To estimate the ability of these lattices to transmit the information used in contrast sensitivity and visual acuity tasks, we constructed ideal-observer models with the optics and photoreceptors of the neonatal eye at retinal eccentricities of 0, 5, and 10 degrees. For ideal-observer models limited by photon noise, the eye's optics, and cone properties, contrast sensitivity was higher in the parafovea and near periphery than in the fovea. However, receptor pooling probably occurs in the neonate's parafovea and near periphery as it does in mature eyes. When we add a receptor-pooling stage to the models of the parafovea and near periphery, ideal acuity is similar in the fovea, parafovea, and near periphery. Comparisons of ideal and real sensitivity indicate that optical and receptoral immaturities impose a significant constraint on neonatal contrast sensitivity and acuity, but that immaturities in later processing stages must also limit visual performance. (+info)Radiotherapy for isolated occult subfoveal neovascularisation in age related macular degeneration: a pilot study. (2/692)
BACKGROUND/AIMS: Teletherapy has been proposed as a possible treatment for choroidal neovascular membranes (CNV), secondary to age related macular degeneration (AMD) not amenable to laser photocoagulation. The aim of this prospective study has been to investigate the effect of teletherapy on isolated occult choroidal neovascular membranes of subfoveal location. METHODS: 28 AMD patients presenting with retrofoveal isolated occult CNV demonstrated by fluorescein angiography were treated by external beam radiation. A complete ophthalmological examination, fluorescein angiography, and indocyanine green angiography (ICG) were performed within 15 days before treatment and repeated at follow up. A total dose of 16 Gy was applied in four sessions of 4 Gy using a 4 MeV photon beam. Follow up ranged from 6 to 9 months (mean follow up 6.4 months). RESULTS: Visual acuity was found to be stable in 68% of the cases. The decrease in visual acuity was of 3-6 lines in 18% and of more than 6 lines in 10% of the eyes at last examination. On fluorescein angiography the size of the lesion area was found to be stable in 67%, decreased in 13%, and increased in 20% of the cases. On ICG angiography the size of the CNV was stable in 93% and increased in 7% of the cases. All the eyes experiencing a visual acuity decrease showed either no change or an increase in size of the membrane on fluorescein angiography and/or on ICG. CONCLUSION: According to this study with strict inclusion criteria, external beam radiotherapy seems to have a beneficial effect on the evolution of isolated occult subfoveal CNV. (+info)Contour integration in the peripheral field. (3/692)
Contour integration was measured in the normal peripheral field to determine if an explanation based solely on the known peripheral positional uncertainty was sufficient to explain performance. The task involved the detection of paths composed of micropatterns with correlated carrier orientations embedded in a field of similar micropatterns of random position and orientation (Field, D. J., Hayes A., & Hess, R. F. (1993). Vision Research, 33, 173-193). The intrinsic positional uncertainty for each eccentric locus was measured with the same stimulus and it did not account for levels of peripheral performance. We show that peripheral performance on this task does not get worse with eccentricity beyond about 10 degrees and that these results can be modeled by simple filtering without any subsequent cellular linking interactions. (+info)The effects of temporal noise and retinal illuminance on foveal flicker sensitivity. (4/692)
We measured foveal flicker sensitivity with and without external added temporal noise at various levels of retinal illuminance and described the data with our model of flicker sensitivity comprising: (i) low-pass filtering of the flickering signal plus external temporal and/or quantal noise by the modulation transfer function (MTF) of the retina (R): (ii) high-pass filtering in proportion to temporal frequency by the MTF of the postreceptoral neural pathways (P): (iii) addition of internal white neural noise; and (iv) detection by a temporal matched filter. Without temporal noise flicker sensitivity had a band-pass frequency-dependence at high and medium illuminances but changed towards a low-pass shape above 0.5 Hz at low luminances, in agreement with earlier studies. In strong external temporal noise, however, the flicker sensitivity function had a low-pass shape even at high and medium illuminances and flicker sensitivity was consistently lower with noise than without. At low luminances flicker sensitivity was similar with and without noise. An excellent fit of the model was obtained under the assumption that the only luminance-dependent changes were increases in the cut-off frequency (fc) and maximum contrast transfer of R with increasing luminance. The results imply the following: (i) performance is consistent with detection by a temporal matched filter, but not with a thresholding process based on signal amplitude; (ii) quantal fluctuations do not at any luminance level become a source of dominant noise present at the detector; (iii) the changes in the maximum contrast transfer reflect changes in retinal gain, which at low to moderate luminances implement less-than-Weber adaptation, with a 'square-root' law at the lowest levels; (iv) the changes of fc as function of mean luminance closely parallels time scale changes in cones, but the absolute values of fc are lower than expected from the kinetics of monkey cones at all luminances; (v) the constancy of the high-pass filtering function P indicates that surround antagonism does not weaken significantly with decreasing light level. (+info)Eye movements of rhesus monkeys directed towards imaginary targets. (5/692)
Is the presence of foveal stimulation a necessary prerequisite for rhesus monkeys to perform visually guided eye movements? To answer this question, we trained two rhesus monkeys to direct their eyes towards imaginary targets defined by extrafoveal cues. Independent of the type of target, real or imaginary, the trajectory of target movement determined the type of eye movement produced: steps in target position resulted in saccades and ramps in target position resulted in smooth pursuit eye movements. There was a tendency for the latency of saccades as well as pursuit onset latency to be delayed in the case of an imaginary target in comparison to the real target. The initial eye acceleration during smooth pursuit initiation elicited by an imaginary target decreased in comparison to the acceleration elicited by a real target. The steady-state pursuit gain was quite similar during pursuit of an imaginary or a real target. Our results strengthen the notion that pursuit is not exclusively a foveal function. (+info)Peripheral vision and oculomotor control during visual search. (6/692)
The present study concerns the dynamics of multiple fixation search. We tried to gain insight into: (1) how the peripheral and foveal stimulus affect fixation duration; and (2) how fixation duration affects the peripheral target selection for saccades. We replicated the non-corroborating results of Luria and Strauss (1975) ('Eye movements during search for coded and uncoded targets', Perception and Psychophysics 17, 303-308) (saccades were selective), and Zelinsky (1996) (Using eye movements to assess the selectivity of search movements. Vision research 36(14), 2177-2187) (saccades were not selective), by manipulating the critical features for peripheral selection and discrimination separately. We found search to be more selective and efficient when the selection task was easy or when fixations were long-lasting. Remarkably, subjects did not increase their fixation durations when the peripheral selection task was more difficult. Only the discrimination task affected the fixation duration. This implies that the time available for peripheral target selection is determined mainly by the discrimination task. The results of the present experiment suggest that, besides the difficulty of the peripheral selection task, fixation duration is an important factor determining the selection of potential targets for eye movements. (+info)Contrast dependency of foveal spatial functions: orientation, vernier, separation, blur and displacement discrimination and the tilt and Poggendorff illusions. (7/692)
To examine the effect of reducing luminance contrast in human foveal vision, discrimination thresholds were measured in four tasks and also a numerical measure of two visual illusions were obtained by a nulling technique. The patterns used for all tasks were made very similar to facilitate comparison between them--all featured luminance step edges whose contrast could be varied from near unity down to the detection threshold. Orientation, vernier and blur discrimination thresholds rise on average 5-6-fold when the contrast is reduced from near unity to a Michelson value of 0.03. Jump displacement thresholds are somewhat more robust to contrast reduction, and the curve of separation discrimination versus contrast is much shallower, rising by a factor of about 2. The magnitude of the Poggendorff and tilt illusions changes very little until the inducing contours are barely detectable. (+info)Temporal resolution deficits in the visual fields of MS patients. (8/692)
We assessed the relationship between temporal resolution and MS-induced neuropathy. A diagnostic strategy comprising assessments of temporal resolution at 16 points in the extra-foveal visual field up to 12 degrees from the fovea was first compared with foveal temporal resolution and with a standard VEP procedure in the same MS patients. At the group level, foveal temporal resolution was less sensitive to demyelination than the 16-point diagnostic strategy, the detection rate of which was comparable to that of the VEP procedure. Cross-sensitivity of the VEP and the 16-point diagnostic procedure was low. Subsequently, the average severity of MS-induced temporal resolution deficits was studied at three retinal loci of the same size but different eccentricities. Foveal deficits were not significantly greater than more peripheral deficits within the central 12 degrees. (+info)I'm sorry, but I couldn't find any information on a medical term called "Aotidae." It's possible that you may have misspelled the term or that it is not commonly used in the medical field. If you could provide more context or information about where you heard or saw this term, I may be able to assist you further.
Cone opsins are a type of photopigment found in the retina of the eye. They are responsible for detecting light and color in the visible spectrum. There are three types of cone opsins, each of which is sensitive to different wavelengths of light: short-wavelength (S-cone), medium-wavelength (M-cone), and long-wavelength (L-cone) cone opsins. These cone opsins work together to allow humans to perceive a wide range of colors and shades.
In the medical field, "cats" typically refers to Felis catus, which is the scientific name for the domestic cat. Cats are commonly kept as pets and are known for their agility, playful behavior, and affectionate nature. In veterinary medicine, cats are commonly treated for a variety of health conditions, including respiratory infections, urinary tract infections, gastrointestinal issues, and dental problems. Cats can also be used in medical research to study various diseases and conditions, such as cancer, heart disease, and neurological disorders. In some cases, the term "cats" may also refer to a group of animals used in medical research or testing. For example, cats may be used to study the effects of certain drugs or treatments on the immune system or to test new vaccines.
Dicrocoeliasis is a parasitic infection caused by the liver fluke Dicrocoelium dendriticum. The infection is found in many parts of the world, particularly in areas where grazing animals such as sheep, goats, and cattle are raised. The fluke infects the liver of the animal, causing damage and potentially leading to liver failure. In humans, the infection is rare and typically occurs when people consume raw or undercooked meat from infected animals. Symptoms of dicrocoeliasis in humans may include abdominal pain, fever, and jaundice. Treatment typically involves the use of antiparasitic medications.
In the medical field, "cell count" refers to the measurement of the number of cells present in a specific sample of tissue or fluid. This measurement is typically performed using a microscope and a specialized staining technique to distinguish between different types of cells. For example, a complete blood count (CBC) is a common laboratory test that measures the number and types of cells in the blood, including red blood cells, white blood cells, and platelets. Similarly, a urine analysis may include a cell count to measure the number of white blood cells or bacteria present in the urine. Cell counts can be used to diagnose a variety of medical conditions, such as infections, inflammation, or cancer. They can also be used to monitor the effectiveness of treatments or to detect any changes in the body's cellular makeup over time.
The choroid is a layer of blood vessels and connective tissue located between the retina and the sclera of the eye. It is responsible for providing oxygen and nutrients to the retina, and for removing waste products from the retina. The choroid is also involved in regulating the amount of light that enters the eye and in maintaining the shape of the eye. In some cases, abnormalities in the choroid can lead to vision problems or other eye disorders.
In the medical field, a scotoma refers to a visual field defect or loss of vision in a specific area of the visual field. It is typically caused by damage to the retina, optic nerve, or other structures in the eye that are responsible for transmitting visual information to the brain. Scotomas can be classified as central or peripheral, depending on the location of the visual field loss. Central scotomas involve a loss of vision in the center of the visual field, while peripheral scotomas involve a loss of vision in the outer edges of the visual field. Scotomas can be caused by a variety of conditions, including glaucoma, diabetic retinopathy, macular degeneration, and optic neuritis. Treatment for scotomas depends on the underlying cause and may include medications, surgery, or other interventions to slow or stop the progression of the underlying condition.
Retinal Perforations refer to a hole or tear in the retina, which is the light-sensitive layer of tissue at the back of the eye. This can occur due to various reasons such as trauma, high blood pressure, or eye infections. Retinal Perforations can lead to a condition called retinal detachment, which is a serious medical emergency that requires prompt medical attention. Retinal detachment occurs when the retina separates from the underlying tissue, causing vision loss and potentially permanent damage to the eye. Treatment for Retinal Perforations may include surgery to repair the tear or hole in the retina, as well as medications to manage any underlying conditions that may have contributed to the perforation.
Contrast sensitivity is a measure of the ability of the human eye to distinguish between different levels of brightness or intensity in an image. It is an important aspect of visual function and is often used to assess the quality of vision in individuals with various eye conditions, such as cataracts, glaucoma, and age-related macular degeneration. In a contrast sensitivity test, the patient is shown a series of visual stimuli that vary in contrast, and asked to identify the orientation or shape of the stimuli. The test is typically performed under standardized conditions, such as a specific brightness level and viewing distance, to ensure that the results are accurate and reliable. The results of a contrast sensitivity test can provide valuable information about the patient's visual function and can help guide treatment decisions. For example, if a patient has low contrast sensitivity, it may indicate that they are having difficulty seeing details in low light conditions or when viewing objects against a complex background. This information can be used to recommend corrective lenses, such as high-contrast glasses, or to suggest further testing to identify and treat any underlying eye conditions.
Scleral diseases refer to disorders that affect the sclera, which is the white, tough outer layer of the eye. The sclera provides structural support to the eye and helps to maintain its shape. Scleral diseases can be classified into several categories, including inflammatory, infectious, neoplastic, and degenerative diseases. Some examples of scleral diseases include: 1. Scleritis: Inflammation of the sclera that can cause pain, redness, and sensitivity to light. 2. Scleromalacia perforans: A rare condition in which the sclera becomes thin and weak, leading to the formation of small holes. 3. Scleroma: A chronic inflammatory disease that affects the sclera and other connective tissues in the body. 4. Scleroderma: A connective tissue disorder that affects the skin, blood vessels, and internal organs, including the sclera. 5. Sclerotic keratitis: A rare condition in which the sclera becomes thickened and opaque, leading to vision loss. 6. Sclerotic glaucoma: A type of glaucoma that is caused by the thickening of the sclera, which can block the flow of aqueous humor out of the eye. Treatment for scleral diseases depends on the specific condition and its severity. In some cases, medications may be used to reduce inflammation or manage symptoms. In more severe cases, surgery may be necessary to repair or replace damaged tissue.
Color vision defects, also known as color blindness, are conditions in which an individual has difficulty distinguishing between certain colors or perceiving colors in a different way than others. This can be caused by a variety of factors, including genetic mutations, eye diseases, exposure to certain chemicals or toxins, and head injuries. There are several different types of color vision defects, including red-green color blindness, blue-yellow color blindness, and total color blindness. Red-green color blindness is the most common type, and it affects the ability to distinguish between red and green colors. Blue-yellow color blindness affects the ability to distinguish between blue and yellow colors, while total color blindness, also known as achromatopsia, affects the ability to see any colors at all. Color vision defects can have a significant impact on an individual's daily life, as they can make it difficult to perform certain tasks, such as driving, reading, or identifying certain types of materials. In some cases, color vision defects may also be a sign of an underlying medical condition, such as a retinal disease or a neurological disorder, and it is important for individuals with color vision defects to see an eye doctor for a proper diagnosis and treatment.
Macular degeneration is a medical condition that affects the macula, which is the central part of the retina in the eye responsible for sharp, central vision. There are two main types of macular degeneration: dry and wet. Dry macular degeneration is the most common form and is characterized by the gradual accumulation of small yellow deposits called drusen in the macula. These deposits can cause the retina to thin and the macula to become damaged, leading to a loss of central vision. Wet macular degeneration is less common but more severe. It occurs when abnormal blood vessels grow beneath the retina and leak fluid or blood, causing damage to the macula and leading to a rapid loss of vision. Both forms of macular degeneration can be treated, but the best course of action depends on the severity of the condition and the individual patient's needs. Treatment options may include lifestyle changes, medications, or surgery.
Retinal diseases refer to a group of medical conditions that affect the retina, which is the light-sensitive layer of tissue at the back of the eye. The retina is responsible for converting light into electrical signals that are transmitted to the brain, where they are interpreted as visual images. Retinal diseases can affect any part of the retina, including the photoreceptor cells (rods and cones), the blood vessels, and the supporting cells. Some common types of retinal diseases include: 1. Age-related macular degeneration (AMD): A progressive disease that affects the central part of the retina, leading to vision loss. 2. Diabetic retinopathy: A complication of diabetes that can cause damage to the blood vessels in the retina, leading to vision loss. 3. Retinal detachment: A condition in which the retina separates from the underlying tissue, leading to vision loss if left untreated. 4. Retinitis pigmentosa: A group of inherited retinal diseases that cause progressive vision loss due to the death of photoreceptor cells. 5. Cataracts: A clouding of the lens in the eye that can cause vision loss. Retinal diseases can be treated with a variety of methods, including medication, laser therapy, surgery, and lifestyle changes. Early detection and treatment are crucial for preserving vision in people with retinal diseases.
Myopia, also known as nearsightedness, is a common eye condition in which a person can see objects clearly up close but has difficulty seeing objects that are far away. Degenerative myopia, also known as pathologic myopia, is a more severe form of myopia that is characterized by progressive eye growth and increased nearsightedness over time. This can lead to a variety of complications, including retinal detachment, glaucoma, and cataracts. Treatment for degenerative myopia may include glasses or contact lenses, as well as surgery to correct the vision.
An epiretinal membrane (ERM) is a thin, fibrous tissue that grows on the surface of the retina, the light-sensitive layer at the back of the eye. It is a common condition that can occur in people of all ages, but it is more common in older adults. ERM can cause a range of symptoms, including blurred vision, distorted vision, and the appearance of dark spots or "floaters" in the field of vision. In some cases, ERM can also cause vision loss if it thickens and pulls on the retina, causing it to detach. Treatment for ERM depends on the severity of the condition and the symptoms it is causing. In some cases, ERM may not cause any problems and may not require treatment. However, if ERM is causing significant vision loss or other symptoms, it may be treated with laser therapy or surgery to remove the membrane and restore normal vision.
Macular edema is a medical condition that occurs when there is fluid accumulation in the macula, which is the central part of the retina responsible for sharp, central vision. This fluid accumulation can cause swelling and damage to the macula, leading to vision loss or distortion. Macular edema can be caused by a variety of factors, including diabetes, high blood pressure, retinal vein occlusion, and age-related macular degeneration. It can also be a complication of certain eye surgeries or injuries. Treatment for macular edema depends on the underlying cause and severity of the condition. In some cases, medications such as anti-inflammatory drugs or steroids may be prescribed to reduce inflammation and swelling. Laser therapy or photodynamic therapy may also be used to treat certain types of macular edema. In severe cases, surgery may be necessary to remove the fluid and restore vision.
Lipofuscin is a yellow-brown, granular pigment that accumulates in cells over time, particularly in older cells. It is composed of oxidized lipids, proteins, and other cellular debris that have been broken down by enzymes. In the medical field, lipofuscin is often seen in various tissues and organs, particularly in the liver, spleen, and brain. It is a normal part of aging and is often associated with the accumulation of cellular waste products. However, excessive accumulation of lipofuscin has been linked to various diseases and conditions, including Alzheimer's disease, Parkinson's disease, and age-related macular degeneration. Lipofuscin accumulation can also be a sign of certain types of liver disease, such as non-alcoholic fatty liver disease and cirrhosis. In these cases, the accumulation of lipofuscin can be a marker of liver damage and can be used to monitor the progression of the disease.
Vitreous detachment is a condition in which the vitreous humor, a clear gel-like substance that fills the inside of the eye, separates from the retina, the light-sensitive layer at the back of the eye. This can occur as a result of aging, injury, or certain medical conditions such as diabetes or high blood pressure. Vitreous detachment is usually a benign condition and does not typically cause vision loss. However, in some cases, it can cause symptoms such as floaters, which are small specks or cobwebs that appear in the field of vision, or, which are brief flashes of light. In rare cases, a large detachment can cause a retinal tear or hole, which can lead to more serious vision problems. Treatment for vitreous detachment is typically not necessary unless it is causing significant symptoms or there is a risk of retinal detachment. In these cases, a doctor may recommend observation, medication, or surgery to repair the retinal tear or hole.
Fovea centralis
Macula
Foveola
Cherry-red spot
Human eye
Cattle
Photoreceptor cell
Retina
Adaptation (eye)
Foveal avascular zone
Jumping spider
Fovea
Optography
Christopher Dewdney
Outline of human anatomy
List of MeSH codes (A09)
Globe (human eye)
Visual acuity
Cone cell
Retinal pigment epithelium
Blue-cone monochromacy
Microperimetry
Acanthogonatus centralis
Bird vision
Lemur
Acanthogonatus parana
Acanthogonatus confusus
Dog anatomy
List of Empis species
Vision in fish
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Visual acuity explained
Retina12
- citation needed] Approximately half the nerve fibers in the optic nerve carry information from the fovea, while the remaining half carry information from the rest of the retina. (wikipedia.org)
- The size of the fovea is relatively small with regard to the rest of the retina. (wikipedia.org)
- A number of mechanisms contribute to this effect, and there is even an anatomical basis for visual attention in the fovea centralis , a pit region in the center of the retina with an increased density of photosensitive cone cells responsible for facilitating detailed visual tasks. (kdnuggets.com)
- The central point for image focus (the visual axis) in the human retina is the fovea. (utah.edu)
- Some vertebrate retinas have instead of a fovea, another specialization of the central retina, known as an area centralis or a visual streak. (utah.edu)
- These muscles, named extraocular muscles rotate the eyeball in the orbits and allow the image to be focussed at all times on the fovea of central retina. (utah.edu)
- Light continues through the vitreous humor and the light converges on the retina, specifically the fovea centralis of the macula. (medscape.com)
- That is, the subject creates for his own use, a not anatomical but physiological fovea, and each point of the retina changes from how it was previously" (mn. (dialecticalsystems.eu)
- A new fovea centralis is formed on the intact half of the retina. (dialecticalsystems.eu)
- A circular field of approximately 6 mm around the fovea is considered the central retina while beyond this is peripheral retina stretching to the ora serrata, 21 mm from the center of the retina (fovea). (org.es)
- Central retina close to the fovea is considerably thicker than peripheral retina (compare Figs. 9 and 10). (org.es)
- The fovea centralis is a thinned-out portion of the retina where only the cones are densely packed. (sciencetechstudy.com)
Macula lutea3
- Anatomical macula / macula lutea / area centralis (clinical: posterior pole): Diameter = 5.5mm (~3.5 disc-diameters) (about 18 deg of VF) Demarcated by the superior and inferior temporal arterial arcades. (wikipedia.org)
- GCL has >5 layers of cells, and highest density of cones Anatomical fovea / fovea centralis (clinical: macula) Area of depression in the centre of the macula lutea. (wikipedia.org)
- At the posterior pole of the eye lateral to the blind spot, there is a yellowish pigmented spot called macula lutea with a central pit called the fovea centralis. (sciencetechstudy.com)
Humans1
- The fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading and driving. (wikipedia.org)
Visual6
- The fovea is a depression in the inner retinal surface, about 1.5 mm wide, the photoreceptor layer of which is entirely cones and which is specialized for maximum visual acuity. (wikipedia.org)
- The high spatial density of cones along with the absence of blood vessels at the fovea accounts for the high visual acuity capability at the fovea. (wikipedia.org)
- The fovea centralis is the area of sharpest visual acuity. (msdmanuals.com)
- Part of the visual field corresponding to the fovea centralis. (medicowesome.com)
- This is due, according to Canguilhem, to a veritable reorganization of the damaged visual field: the hemianopic patient's eye develops a new "functional fovea" (mn. (dialecticalsystems.eu)
- Thus, the area in which [the new fovea centralis ] is located benefits from a higher visual acuity than before. (dialecticalsystems.eu)
Central7
- The fovea centralis is a small, central pit composed of closely packed cones in the eye. (wikipedia.org)
- The perifovea contains an even more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most central fovea. (wikipedia.org)
- The parafovea extends to a radius of 1.25 mm from the central fovea, and the perifovea is found at a 2.75 mm radius from the fovea centralis. (wikipedia.org)
- The center of the fovea is the foveola - about 0.35 mm in diameter - or central pit where only cone photoreceptors are present and there are virtually no rods. (wikipedia.org)
- The central fovea consists of very compact cones, thinner and more rod-like in appearance than cones elsewhere. (wikipedia.org)
- Cones in the central fovea express opsins that are sensitive to green and red light. (wikipedia.org)
- Canguilhem stressed that, in the case of hemianopic patients, macular vision, that is, precise and distinct vision usually due to the action of a tiny part of the eye called fovea , tends to remain approximately intact despite the total blurring of the central part of a visus . (dialecticalsystems.eu)
Area3
- Within the fovea is a region of 0.5mm diameter called the foveal avascular zone (an area without any blood vessels). (wikipedia.org)
- Therefore, the acuity of foveal vision is limited only by the density of the cone mosaic, and the fovea is the area of the eye with the highest sensitivity to fine details. (wikipedia.org)
- In 1795 Sömmering made it clear that the perceptual role of vision is mainly due to this eyeball micro-area, fovea, in which a "reciprocal correspondence of the cells it contains and the nerve fibers can be observed", entailing "the fineness of the sensory and cerebral analysis of light impressions at this point" (mn. (dialecticalsystems.eu)
Center1
- This anatomy is responsible for the depression in the center of the fovea. (wikipedia.org)
Region2
- The fovea is surrounded by the parafovea belt and the perifovea outer region. (wikipedia.org)
- The ellipsoid zone (EZ) in the macular region was disrupted in eight eyes (80%) of which seven were fovea sparing. (nih.gov)
Close1
- As a result of this reorganization, the patient has the impression of looking straight ahead, accommodating [the gaze] no longer from the fovea centralis , but from a point more or less close to it. (dialecticalsystems.eu)
Vision1
- In short, by quoting the French philosopher Maurice Pradines, one could say that "we can benefit from optimal vision through the macula, and also through a specific point, the fovea centralis . (dialecticalsystems.eu)
Rods3
- The center of the fovea is the foveola - about 0.35 mm in diameter - or central pit where only cone photoreceptors are present and there are virtually no rods. (wikipedia.org)
- Starting at the outskirts of the fovea, however, rods gradually appear, and the absolute density of cone receptors progressively decreases. (wikipedia.org)
- It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. (nih.gov)
Cones6
- The fovea centralis is a small, central pit composed of closely packed cones in the eye. (wikipedia.org)
- The perifovea contains an even more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most central fovea. (wikipedia.org)
- The fovea is a depression in the inner retinal surface, about 1.5 mm wide, the photoreceptor layer of which is entirely cones and which is specialized for maximum visual acuity. (wikipedia.org)
- The high spatial density of cones along with the absence of blood vessels at the fovea accounts for the high visual acuity capability at the fovea. (wikipedia.org)
- The central fovea consists of very compact cones, thinner and more rod-like in appearance than cones elsewhere. (wikipedia.org)
- Cones in the central fovea express opsins that are sensitive to green and red light. (wikipedia.org)
Retinal1
- The fovea is located in a small avascular zone and receives most of its oxygen from the vessels in the choroid, which is across the retinal pigment epithelium and Bruch's membrane. (wikipedia.org)