The structure of the mammalian eye owes itself completely to the task of focusing light onto the retina. All of the individual components through which light travels within the eye before reaching the retina are transparent, minimising dimming of the light. The cornea and lens help to converge light rays to focus onto the retina. This light causes chemical changes in the photosensitive cells of the retina, the products of which trigger nerve impu ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases disorders and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Anatomy

See also:

Iris anatomy, Iris anatomy - General structure, Iris anatomy - Histological features, Iris anatomy - Anterior surface features, Iris anatomy - Posterior surface features, Iris anatomy - Embryology, Iris anatomy - Color, Iris anatomy - Genetic and physical factors determining iris color, Iris anatomy - Faking the iris color, Iris anatomy - Iris color as paternity test, Iris anatomy - Different colors in the two eyes, Iris anatomy - Red eye

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The iris is usually strongly pigmented, with colors ranging from brown to green, blue, grey, and hazel. Occasionally its color is due to lack of pigmentation, as in the pinkish-white of oculo-cutaneous albinism, or to obscuration of its pigment by blood vessels, as in the red of an abnormally vascularised iris (although human albinos generally have very light blue eyes, as the unpigmented color of the human iris is a pale blue). Despite the wide range of colors, there is only one pigment that contributes substantially to normal human iris color, the dark pigment called melanin. Structurally, this huge molecule is only slightly different from ...

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Iris anatomy, Iris anatomy - General structure, Iris anatomy - Histological features, Iris anatomy - Anterior surface features, Iris anatomy - Posterior surface features, Iris anatomy - Embryology, Iris anatomy - Color, Iris anatomy - Genetic and physical factors determining iris color, Iris anatomy - Faking the iris color, Iris anatomy - Iris color as paternity test, Iris anatomy - Different colors in the two eyes, Iris anatomy - Red eye

Read more here: » Iris anatomy: Encyclopedia II - Iris anatomy - Color

An eye is an organ that detects light. Different kinds of light-sensitive organs are found in a variety of creatures. The simplest eyes do nothing but detect whether the surroundings are light or dark. More complex eyes are used to provide the sense of vision. Many complex organisms including some mammals, birds, reptiles and fish have two eyes which may be placed on the same plane to be interpreted as a single three-dimensional "image" (binocular vision), as in humans; or on different planes producing two separate "images" (monocular ...

Including:

Eye - Varieties of eyes Eye - Evolution of eyes Eye - Anatomy Eye - Cytology Eye - Acuity Eye - Dynamic range Eye - Adnexa and related parts
Eye - The orbit Eye - Eyebrows Eye - Eyelids Eye - Eyelashes
Eye - Eye movement
Eye - Rapid eye movement Eye - Saccades Eye - Microsaccades Eye - Vestibulo-ocular reflex Eye - Smooth pursuit movement Eye - Optokinetic reflex Eye - Vergence movement Eye - Accommodation
Eye - Diseases disorders and age-related changes

Read more here: » Eye: Encyclopedia - Eye

There are many diseases and disorders that may affect the eyes. As the eye ages certain changes occur that can be attributed to solely the aging process. Most of these anatomic and physiologic processes follow a gradual decline. With aging, the quality of vision worsens due to reasons independent of aging eye diseases. While there are many changes of significance in the nondiseased eye, the most functionally important changes seem to be a reduction in pupil size and the loss of accommodation or focusing capability (presbyopia). The ar ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Diseases, disorders, and age-related changes

How a complex structure like the projecting eye could have evolved is often said to be a difficult question for the theory of evolution. Darwin famously treated the subject of eye evolution in his Origin of Species: To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Evolution of eyes

In most vertebrates and some mollusks the eye works by allowing light to enter it and project onto a light-sensitive panel of cells known as the retina at the rear of the eye, where the light is detected and converted into electrical signals, which are then transmitted to the brain via the optic nerve. Such eyes are typically roughly spherical, filled with a transparent gel-like substance called the vitreous humour, with a focusing lens and often an iris which regulates the intensity of the light that enters the eye. The eyes of cepha ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Varieties of eyes

The structure of the mammalian eye owes itself completely to the task of focusing light onto the retina. All of the individual components through which light travels within the eye before reaching the retina are transparent, minimising dimming of the light. The cornea and lens help to converge light rays to focus onto the retina. This light causes chemical changes in the photosensitive cells of the retina, the products of which trigger nerve impu ...

See also:

Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Anatomy

Animals with compound eyes have a wide field of vision, allowing them to look in many directions. To see more, they have to move their entire head or even body. The visual system in the brain is too slow to process that information if the images are slipping across the retina at more than a few degrees per second (Westheimer and McKee, 1954). Thus, for humans to be able to see while moving, the brain must compensate for the motion of the head by turning the eyes. Another complication for vision in frontal-eyed animals is the developme ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Eye movement

Visual acuity can be measured with several different metrics. Cycles per degree (CPD) measures how much an eye can differentiate one object from another in terms of degree angles. It is essentially no different from angular resolution. To measure CPD, first draw a series of black and white lines of equal width on a grid (similar to a bar code). Next, place the observer at a distance such that the sides of the grid appear one degree apart. If the grid is 1 meter away, then the grid should be about 8.7 millimeters wide. Finally, increas ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Acuity

Eye - The orbit. In many species, the eyes are inset in the portion of the skull known as the orbits or eyesockets. This placement of the eyes helps to protect them from injury. Eye - Eyebrows. In humans, the eyebrows redirect flowing substances (usually rainwater) away from the eye. Water in the eye can alter the refractive properties of the eye and blur vision. It can also wash away the tear fluid, and its beneficial effects, and can damage the cornea, due to osmotic differences between tear fluid and freshwa ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Adnexa and related parts

The retina contains two forms of photosensitive cells - rods and cones. Though structurally and metabolically similar, their function is quite different, though they are equally important to vision. Rod cells are highly sensitive to light allowing them to respond in dim light and dark conditions. These are the cells which allow humans and other animals to see by moonlight, or with very little available light (as in a dark room). However, they do not distinguish between colours, and have low visual acuity (a measure of detail). This is why th ...

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Eye, Eye - Varieties of eyes, Eye - Evolution of eyes, Eye - Anatomy, Eye - Cytology, Eye - Acuity, Eye - Dynamic range, Eye - Adnexa and related parts, Eye - The orbit, Eye - Eyebrows, Eye - Eyelids, Eye - Eyelashes, Eye - Eye movement, Eye - Rapid eye movement, Eye - Saccades, Eye - Microsaccades, Eye - Vestibulo-ocular reflex, Eye - Smooth pursuit movement, Eye - Optokinetic reflex, Eye - Vergence movement, Eye - Accommodation, Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia II - Eye - Cytology

An eye is an organ that detects light. Different kinds of light-sensitive organs are found in a variety of creatures. The simplest eyes do nothing but detect whether the surroundings are light or dark. More complex eyes are used to provide the sense of vision. Many complex organisms including some mammals, birds, reptiles and fish have two eyes which may be placed on the same plane to be interpreted as a single three-dimensional "image" (binocular vision), as in humans; or on different planes producing two separate "images" (monocular ...

Including:

Eye - Varieties of eyes Eye - Evolution of eyes Eye - Anatomy Eye - Cytology Eye - Acuity Eye - Dynamic range Eye - Adnexa and related parts
Eye - Eyebrows Eye - Eyelids Eye - Eyelashes
Eye - Eye movement
Eye - Rapid eye movement Eye - Saccades Eye - Microsaccades Eye - Vestibulo-ocular reflex Eye - Smooth pursuit movement Eye - Optokinetic reflex Eye - Vergence movement Eye - Accommodation
Eye - Diseases, disorders, and age-related changes

Read more here: » Eye: Encyclopedia - Eye

The lens or crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to focus on the retina. In humans, the refractive power of the lens in its natural environment is approximately 15 dioptres, roughly one-fourth of the eye's total power. The lens is flexible and its curvature is controlled by ciliary muscles. By changing the curvature of the lens, one can focus the eye on objects at different dis ...

Including:

Lens anatomy - Diseases

Read more here: » Lens anatomy: Encyclopedia - Lens anatomy

Accommodation is the process by which the eye increases optical power to maintain a clear image (focus). See also. Accommodation reflex Accommodative esotropia Amplitude of accommodation Cycloplegia Edinger-Westphal nucleus Hermann von Helmholtz Lens (anatomy) Negative relative accommodation Positive relative accommodation Presbyopia ...

Read more here: » Accommodation eye: Encyclopedia - Accommodation eye

The face is the front part of the human head from forehead to chin including the head, hair, forehead, eyebrow, eyes, nose, cheek, mouth, lips, teeth, skin, and chin. The face is used for facial expressions, appearance and identity amongst other humans. Face - Anatomy. On the front of the facepiece a line drawn down from the supraorbital notch between the bicuspid teeth to the side of the chin will cut the exit of the second division of the fifth nerve from the infraorbital foramen, a quarter of an inch bel ...

Including:

Face - Anatomy
Face - Eye Face - Jaw
Face - Face surgery Face - Health
Face - Face diseases

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Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs light more than does air. Fish anatomy - Body. Nearly all fish have a streamlined body, which is divided into head, trunk, and tail, although the dividing points are not always externally visible. The head includes the snout, from the eye to the forwardmost point of the upper jaw, the operculum or gill cover, and the cheek ...

Including:

Fish anatomy - Body Fish anatomy - Fins Fish anatomy - Scales

Read more here: » Fish anatomy: Encyclopedia - Fish anatomy

In anatomy, the head of an animal is the anterior part (from anatomical position) that comprises the mouth, the brain and various sensory organs (e.g. organs of sight, hearing, smell and taste). Head - Anatomy. The front (ventrum) of the head, where the eyes and ears and mouth are located, is called the face. The area above the eyes is called the forehead (the front of the head). Below the mouth is the chin. Younger aged humans and some older humans heads have a continuing growing layer ...

Including:

Head - Anatomy
Head - Human head anatomy Head - The face
Head - Cultural import Head - Clothing Head - Pseudoscientific study of the human head

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Ophthalmology is the branch of medicine which deals with the diseases of the eye and their treatment. The word ophthalmology comes from the Greek roots ophthalmos meaning eye and logos meaning word; ophthalmology literally means "the science of eyes." As a discipline it applies to animal eyes also, since the differences from human practice are surprisingly minor and are related mainly to differences in anatomy or prevalence, not differences in disease processes. By convention the term ophthalmolog ...

Including:

Ophthalmology - History of ophthalmology Ophthalmology - Professional requirements Ophthalmology - Sub-specialities Ophthalmology - Ophthalmic surgery Ophthalmology - Famous ophthalmologists

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The anatomical position is a schematic convention for describing the relative morphology of the human body. All terms in the study of anatomy refer to when the body is in this position. The person is oriented in an erect standing position eyes and head facing forward feet forward and perpendicular to the body arms close to the sides and palms of the hands facing forward with fingers extended. It should be noted that this is not the normal position that arms rest in.

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