Schematic diagram of the human eye, with the fovea at the bottom.

The fovea, also known as the fovea centralis, is a part of the eye, located in the center of the macula region of the retina. ^{[1] [2]} The fovea is responsible for sharp central vision, which is necessary in humans for reading, watching television or movies, driving, and any activity where visual detail is of primary importance. The fovea is surrounded by the parafovea belt, and the perifovea outer region:^[2] the parafovea is the intermediate belt where the ganglion cell layer is composed of more than five rows of cells; the perifovea is the outermost region where the ganglion cell layer contains two to four rows of cells, and is where visual acuity is below the optimum. This, in turn, is surrounded by a larger peripheral area that delivers information of low resolution. Image File history File links Schematic_diagram_of_the_human_eye_en. ... Image File history File links Schematic_diagram_of_the_human_eye_en. ... For other uses, see Eye (disambiguation). ... Human eye cross-sectional view. ... Human eye cross-sectional view. ... In psychology, visual perception is the ability to interpret visible light information reaching the eyes which is then made available for planning and action. ... Reading is a process of retrieving and comprehending some form of stored information or ideas. ... This is a dorsal root ganglion (DRG) from a chicken embryo (around stage of day 7) after incubation overnight in NGF growth medium stained with anti-neurofilament antibody. ... Peripheral vision is a part of vision that occurs outside the very center of gaze. ...

Description

The term 'fovea' comes from the Latin, meaning 'pit' or 'arm pit'. As an anatomical term there are several foveae around the body, including in the head of the femur.

The fovea has a more equal ratio of ganglion cells per photoreceptor; all or almost every photoreceptor has one ganglion cell receiving data from it. That is why it has little loss of sensory data, thus it is the area of the eye where high detail can be seen, for example for reading text.^[3] A ganglion cell (or sometimes called a gangliocyte) is a type of neuron located in the retina that receives visual information from photoreceptors via various intermediate cells such as bipolar cells, amacrine cells, and horizontal cells. ... A photoreceptor, or photoreceptor cell, is a specialized type of neuron found in the eyes retina that is capable of phototransduction. ... Look up text in Wiktionary, the free dictionary. ...

The fovea centralis is a pit in the surface of the retinas of many types of fish, reptiles and birds and amongst mammals is found only in simian primates. The retinal fovea takes slightly different forms in different types of animals. For example, in primates cone photoreceptors line the base of the foveal pit, the cells which elsewhere in the retina form more superficial layers having been displaced away from the foveal region during late fetal and early postnatal life. Other foveae may show only a reduced thickness in the inner cell layers, rather than an almost complete absence.

At the center of the macula, approximately on the visual axis, there is a pit (termed the "foveal pit") with a diameter of about 1.0 mm, that is associated with a high concentration of cone photoreceptors. The centre of the fovea is the foveola - about 0.2mm in diameter - where only cone photoreceptors are present and there are virtually no rods.^[1] A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... Normalized responsivity spectra of human cone cells, S, M, and L types Cone cells, or cones, are photoreceptor cells in the retina of the eye which function best in relatively bright light. ... Rod cells, or rods, are photoreceptor cells in the retina of the eye that can function in less intense light than can the other type of photoreceptor, cone cells. ...

Compared to the rest of the retina, the cones in the foveal pit have a smaller diameter and can therefore be more densely packed (in a hexagonal pattern). The high spatial density of cones accounts for the high visual acuity capability at the fovea. This is enhanced by the local absence of retinal blood vessels from the fovea - which if present would interfere with the passage of light striking the foveal cone mosaic. The absence of inner retinal cells from the foveae of primates is assumed also to contribute to the high acuity function of the fovea although there is no convincing evidence to this effect, since the refractive index of the retina is not significantly different from that of the vitreous humour filling the pit. Human eye cross-sectional view. ... For other uses, see Hexagon (disambiguation). ...

Due to the lack of a retinal blood supply, the fovea must receive oxygen from the vessels in the choroid, which is across the retinal pigment epithelium and Bruch's membrane. This blood supply alone does not satisfy the metabolic needs of the fovea under conditions of bright light, and the fovea thus exists in a state of hypoxia when under bright illumination. The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye lying between the retina and the sclera. ... The retinal pigment epithelium is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells. ... Bruchs membrane is the innermost layer of the choroid. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ...

Since cones contain the pigmented opsins that allow humans to discriminate color, the fovea is largely responsible for the color vision in humans which is superior to that of most other mammals. A rhodopsin molecule in the cell membrane. ... Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit. ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex...

The foveal pit is not located exactly on the optical axis, but is displaced about 4 to 8 degrees temporal to it. In telecommunication, the term optical axis has the following meanings: 1. ...

The fovea comprises less than 1% of retinal size but takes up over 50% of the visual cortex in the brain. ^[4] The fovea sees only the central two degrees of the visual field, which is roughly equivalent to twice the width of your thumbnail at arm's length. ^[5] Brodmann area 17 (primary visual cortex) is shown in red in this image which also shows area 18 (orange) and 19 (yellow) The visual cortex refers to the primary visual cortex (also known as striate cortex or V1) and extrastriate visual cortical areas such as V2, V3, V4, and V5. ...

Surrounding the foveal pit is the foveal rim, where the neurons displaced from the pit are located. This is the thickest part of the retina.

Since the fovea does not have rods, it is not sensitive to dim lights. Astronomers know this: in order to observe a dim star, they use averted vision, looking out of "the side of their eyes". Galileo is often referred to as the Father of Modern Astronomy. ... Averted vision is a technique for viewing faint objects which involves not looking directly at the object, but looking a little off to the side, while continuing to concentrate on the object. ...

The fovea is covered in a yellow pigment called xanthophyll,^[1] with the carotenoids zeaxanthin and lutein (Balashov and Bernstein, 1998), present in the cone axons of the Henle fibre layer.^[1] The pigment area absorbs blue light and is probably an evolutionary adaptation to the problem of chromatic aberration. This article or section does not cite its references or sources. ... The orange ring surrounding Grand Prismatic Spring is due to carotenoid molecules, produced by huge mats of algae and bacteria. ... Zeaxanthin is one of the two carotenoids contained within the retina. ... Lutein (LOO-teen) (from Latin lutea meaning yellow) is one of over 600 known naturally occurring carotenoids. ... An axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... On top is corner detail in a photograph taken with a higher quality lens; bottom is a similar photograph taken with a wide angle lens showing visible chromatic aberration (especially at the dark edges on the right). ...

Additional images

Horizontal section of the eyeball. Image File history File links Gray869. ...

References

See also

• Eye movement
• Eye movement in language reading
• Eye movement in music reading
• Gaze-contingency paradigm
• Macular degeneration