How does the eyeball? The eye is the organ of vision. This is an optical system that allows us to perceive light, darkness, shapes and colors ... Before understanding the mechanism of vision, an overview of the different structures of the eye. The eyeball: structures and functions The eyeball is a spherical body and rounded small (2.5 cm diameter). It consists of several structures, including the roles and responsibilities are well defined. The eye captures light and transforms it into nerve impulses to be transmitted to the brain via the optic nerve. The sclera Sclera (white of the eye) is a white membrane and is the outermost layer that protects the eyeball. The sclera is composed of connective tissue but contains few blood vessels. The cornea The cornea relays forward the sclera and is not vascularized and captures light rays to get him in the eye and contains the aqueous humor and is permanently moistened with tears. The cornea covers the pupil and involved largely the mechanism of "refraction". The contact of a foreign object with the cornea results in an increase of the tear secretion. A review involving contact with the cornea often use anesthetics contact. The retina The retina is the layer that captures light transmitted to the brain. It is made of pigment layers and layers of nerve. Nerve layer, being a component of the central nervous system, is constituted by cells called "photoreceptors" The rods are very sensitive to light and can capture the lights very low intensities. Night vision and color perception are mainly provided by these types of photoreceptors. The rods are innervated by fiber optic nerve. The cones are more numerous and are the center of the yellow spot or macula (fovea), at which the vision is maximized. These types of photoreceptors provide daylight vision and are also sensitive to color and contain pigments that can perceive easily distinguish red, green and blue color. The yellow spot or macula The yellow spot is a point on the retina is back, the level of visual acuity is maximum at a central point of the macula. This is the fovea. The blind spot The blind spot (optic disc or disc) is a point near the yellow spot. This contains no photoreceptors and can not detect any signal light. The crystalline The lens comes in convex lens, and participates in the mechanism of near vision and shape changes in the phenomenon of "accommodation." It is maintained by the suspensory and separate eyeball ligaments in 2 parts: The anterior chamber contains aqueous humor, which is constantly renewed Posterior chamber contains the vitreous humor or the vitreous, it is a gelatinous substance made of hyaluronic acid which gives shape and substance to the eyeball. The vitreous provides intraocular pressure of the eye. The pupil and the iris The pupil is like a diaphragm at the center of the eye and allows the passage of light rays. The iris is a smooth muscle that allows the opening of the pupil. This varies the amount of light which passes through the eye, for regulating the size of the pupil. If blinding sunlight, the iris retracts to limit the opening of the pupil. In case of night vision, the maximum aperture is to collect light rays in the dark. The ciliary body The ciliary body is a structure of smooth muscle, for contraction, it ensures the lens curvature (accommodation phenomenon) in the near vision. Choroid The choroid is a highly vascular structure and looks like a black membrane. This layer captures the light and makes sorting between useful and useless rays. The extraocular muscles The extraocular eye muscles are responsible for movements of the eye (6 in number) and of the upper eyelid (provided by a single muscle). These include movements of the eye upward, downward, outward, forward and rotational movements. The mechanism of vision The eye works like a camera with him. He sees the characteristics of light to transmit nerve impulses to the brain. Examples: Cholesterol, osteoarthritis, Alzheimer's, ... Search A specific health ZExamens oeilComment works of the eyeball? How does the eyeball? To go further: Health and Life | Health and Technology | Medical Examinations | How does the eyeball? The eye is the organ of vision. This is an optical system that allows us to perceive light, darkness, shapes and colors ... Before understanding the mechanism of vision, an overview of the different structures of the eye. Summary + The eyeball: structures and functions + The mechanism of vision Specific examinations of the eye The eye or eyeball How does the eyeball? Eye examinations: Principles All examinations in ophthalmology Print Facebook Twitter Google Bookmarks The eyeball: structures and functions The eyeball is a spherical body and rounded small (2.5 cm diameter). It consists of several structures, including the roles and responsibilities are well defined. The eye captures light and transforms it into nerve impulses to be transmitted to the brain via the optic nerve. The sclera Sclera (white of the eye) is a white membrane and is the outermost layer that protects the eyeball. The sclera is composed of connective tissue but contains few blood vessels. The cornea The cornea relays forward the sclera and is not vascularized and captures light rays to get him in the eye and contains the aqueous humor and is permanently moistened with tears. The cornea covers the pupil and involved largely the mechanism of "refraction". The contact of a foreign object with the cornea results in an increase of the tear secretion. A review involving contact with the cornea often use anesthetics contact. The retina The retina is the layer that captures light transmitted to the brain. It is made of pigment layers and layers of nerve. Nerve layer, being a component of the central nervous system, is constituted by cells called "photoreceptors" The rods are very sensitive to light and can capture the lights very low intensities. Night vision and color perception are mainly provided by these types of photoreceptors. The rods are innervated by fiber optic nerve. The cones are more numerous and are the center of the yellow spot or macula (fovea), at which the vision is maximized. These types of photoreceptors provide daylight vision and are also sensitive to color and contain pigments that can perceive easily distinguish red, green and blue color. The yellow spot or macula The yellow spot is a point on the retina is back, the level of visual acuity is maximum at a central point of the macula. This is the fovea. The blind spot The blind spot (optic disc or disc) is a point near the yellow spot. This contains no photoreceptors and can not detect any signal light. The crystalline The lens comes in convex lens, and participates in the mechanism of near vision and shape changes in the phenomenon of "accommodation." It is maintained by the suspensory and separate eyeball ligaments in 2 parts: The anterior chamber contains aqueous humor, which is constantly renewed Posterior chamber contains the vitreous humor or the vitreous, it is a gelatinous substance made of hyaluronic acid which gives shape and substance to the eyeball. The vitreous provides intraocular pressure of the eye. The pupil and the iris The pupil is like a diaphragm at the center of the eye and allows the passage of light rays. The iris is a smooth muscle that allows the opening of the pupil. This varies the amount of light which passes through the eye, for regulating the size of the pupil. If blinding sunlight, the iris retracts to limit the opening of the pupil. In case of night vision, the maximum aperture is to collect light rays in the dark. The iris contains a pigment called "melanin" which gives it its color (blue, brown or green). The ciliary body The ciliary body is a structure of smooth muscle, for contraction, it ensures the lens curvature (accommodation phenomenon) in the near vision. Choroid The choroid is a highly vascular structure and looks like a black membrane. This layer captures the light and makes sorting between useful and useless rays. The extraocular muscles The extraocular eye muscles are responsible for movements of the eye (6 in number) and of the upper eyelid (provided by a single muscle). These include movements of the eye upward, downward, outward, forward and rotational movements. The mechanism of vision The eye works like a camera with him. He sees the characteristics of light to transmit nerve impulses to the brain. The light rays are captured by the cornea and projected to the fovea, crossing all structures inside the eyel
How does the
eyeball?
The eye is the
organ of vision. This is an optical system that allows us to perceive light,
darkness, shapes and colors ... Before understanding the mechanism of vision,
an overview of the different structures of the eye.
The eyeball:
structures and functions
The eyeball is a
spherical body and rounded small (2.5 cm diameter). It consists of several
structures, including the roles and responsibilities are well defined. The eye
captures light and transforms it into nerve impulses to be transmitted to the
brain via the optic nerve.
The sclera
Sclera (white of
the eye) is a white membrane and is the outermost layer that protects the
eyeball. The sclera is composed of connective tissue but contains few blood
vessels.
The cornea
The cornea
relays forward the sclera and is not vascularized and captures light rays to
get him in the eye and contains the aqueous humor and is permanently moistened
with tears. The cornea covers the pupil and involved largely the mechanism of
"refraction".
The contact of a
foreign object with the cornea results in an increase of the tear secretion.
A review
involving contact with the cornea often use anesthetics contact.
The retina
The retina is
the layer that captures light transmitted to the brain. It is made of pigment
layers and layers of nerve.
Nerve layer,
being a component of the central nervous system, is constituted by cells called
"photoreceptors"
The rods are
very sensitive to light and can capture the lights very low intensities. Night
vision and color perception are mainly provided by these types of
photoreceptors. The rods are innervated by fiber optic nerve.
The cones are
more numerous and are the center of the yellow spot or macula (fovea), at which
the vision is maximized. These types of photoreceptors provide daylight vision
and are also sensitive to color and contain pigments that can perceive easily
distinguish red, green and blue color.
The yellow spot
or macula
The yellow spot
is a point on the retina is back, the level of visual acuity is maximum at a
central point of the macula. This is the fovea.
The blind spot
The blind spot
(optic disc or disc) is a point near the yellow spot. This contains no
photoreceptors and can not detect any signal light.
The crystalline
The lens comes
in convex lens, and participates in the mechanism of near vision and shape
changes in the phenomenon of "accommodation." It is maintained by the
suspensory and separate eyeball ligaments in 2 parts:
The anterior
chamber contains aqueous humor, which is constantly renewed
Posterior
chamber contains the vitreous humor or the vitreous, it is a gelatinous
substance made of hyaluronic acid which gives shape and substance to the
eyeball. The vitreous provides intraocular pressure of the eye.
The pupil and
the iris
The pupil is
like a diaphragm at the center of the eye and allows the passage of light rays.
The iris is a
smooth muscle that allows the opening of the pupil. This varies the amount of
light which passes through the eye, for regulating the size of the pupil. If
blinding sunlight, the iris retracts to limit the opening of the pupil. In case
of night vision, the maximum aperture is to collect light rays in the dark.
The ciliary body
The ciliary body
is a structure of smooth muscle, for contraction, it ensures the lens curvature
(accommodation phenomenon) in the near vision.
Choroid
The choroid is a
highly vascular structure and looks like a black membrane. This layer captures
the light and makes sorting between useful and useless rays.
The extraocular
muscles
The extraocular
eye muscles are responsible for movements of the eye (6 in number) and of the
upper eyelid (provided by a single muscle). These include movements of the eye
upward, downward, outward, forward and rotational movements.
The mechanism of
vision
The eye works
like a camera with him. He sees the characteristics of light to transmit nerve
impulses to the brain.
Examples:
Cholesterol, osteoarthritis, Alzheimer's, ...
Search
A specific
health ZExamens oeilComment works of the eyeball?
How does the eyeball?
To go further:
Health and Life | Health and Technology | Medical Examinations |
How does the
eyeball?
The eye is the
organ of vision. This is an optical system that allows us to perceive light,
darkness, shapes and colors ... Before understanding the mechanism of vision,
an overview of the different structures of the eye.
Summary
+ The eyeball:
structures and functions
+ The mechanism
of vision
Specific
examinations of the eye
The eye or
eyeball
How does the
eyeball?
Eye
examinations: Principles
All examinations
in ophthalmology
Print
Facebook Twitter
Google Bookmarks
The eyeball:
structures and functions
The eyeball is a
spherical body and rounded small (2.5 cm diameter). It consists of several
structures, including the roles and responsibilities are well defined. The eye
captures light and transforms it into nerve impulses to be transmitted to the
brain via the optic nerve.
The sclera
Sclera (white of
the eye) is a white membrane and is the outermost layer that protects the
eyeball. The sclera is composed of connective tissue but contains few blood
vessels.
The cornea
The cornea
relays forward the sclera and is not vascularized and captures light rays to
get him in the eye and contains the aqueous humor and is permanently moistened
with tears. The cornea covers the pupil and involved largely the mechanism of
"refraction".
The contact of a
foreign object with the cornea results in an increase of the tear secretion.
A review
involving contact with the cornea often use anesthetics contact.
The retina
The retina is
the layer that captures light transmitted to the brain. It is made of pigment
layers and layers of nerve.
Nerve layer,
being a component of the central nervous system, is constituted by cells called
"photoreceptors"
The rods are
very sensitive to light and can capture the lights very low intensities. Night
vision and color perception are mainly provided by these types of
photoreceptors. The rods are innervated by fiber optic nerve.
The cones are
more numerous and are the center of the yellow spot or macula (fovea), at which
the vision is maximized. These types of photoreceptors provide daylight vision
and are also sensitive to color and contain pigments that can perceive easily
distinguish red, green and blue color.
The yellow spot
or macula
The yellow spot
is a point on the retina is back, the level of visual acuity is maximum at a
central point of the macula. This is the fovea.
The blind spot
The blind spot
(optic disc or disc) is a point near the yellow spot. This contains no
photoreceptors and can not detect any signal light.
The crystalline
The lens comes
in convex lens, and participates in the mechanism of near vision and shape
changes in the phenomenon of "accommodation." It is maintained by the
suspensory and separate eyeball ligaments in 2 parts:
The anterior
chamber contains aqueous humor, which is constantly renewed
Posterior
chamber contains the vitreous humor or the vitreous, it is a gelatinous
substance made of hyaluronic acid which gives shape and substance to the
eyeball. The vitreous provides intraocular pressure of the eye.
The pupil and
the iris
The pupil is
like a diaphragm at the center of the eye and allows the passage of light rays.
The iris is a
smooth muscle that allows the opening of the pupil. This varies the amount of
light which passes through the eye, for regulating the size of the pupil. If
blinding sunlight, the iris retracts to limit the opening of the pupil. In case
of night vision, the maximum aperture is to collect light rays in the dark.
The iris
contains a pigment called "melanin" which gives it its color (blue,
brown or green).
The ciliary body
The ciliary body
is a structure of smooth muscle, for contraction, it ensures the lens curvature
(accommodation phenomenon) in the near vision.
Choroid
The choroid is a
highly vascular structure and looks like a black membrane. This layer captures
the light and makes sorting between useful and useless rays.
The extraocular
muscles
The extraocular
eye muscles are responsible for movements of the eye (6 in number) and of the
upper eyelid (provided by a single muscle). These include movements of the eye
upward, downward, outward, forward and rotational movements.
The mechanism of
vision
The eye works
like a camera with him. He sees the characteristics of light to transmit nerve
impulses to the brain.
The light rays
are captured by the cornea and projected to the fovea, crossing all structures
inside the eye.
The normal
mechanism is different depending on whether it is a:
long sight,
which is generally provided by the refraction of the cornea.
near vision
(less than 6 meters), which requires the accommodation phenomenon with the
curvature of the lens.
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