Macula

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Macula

The macula or macula lutea (from Latin

Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
macula, "spot" + lutea, "yellow") is an oval-shaped highly pigmented yellow

Yellow

Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, but does not significantly stimulate the S cone cells; that is, light with much red and green but not very much blue....
spot near the center of the retina

Retina

The vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera....
of the human eye

Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cell

Ganglion cell

A retinal ganglion cell is a type of neuron located near the inner surface of the retina of the eye. It receives visual information from photoreceptor cells via two intermediate neuron types: Bipolar cell of the retinas and amacrine cells....
s. Near its center is the fovea

Fovea

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.The fovea is responsible for sharp central Visual perception , which is necessary in humans for reading , watching television or movies, driving, and any activity where visual detail is of primary importance....
, a small pit that contains the largest concentration of cone cell

Cone cell

Cone cells, or cones, are photoreceptor cells in the retina of the eye which function best in relatively bright light. The cone cells gradually become sparser towards the periphery of the retina....
s in the eye and is responsible for central vision, and also contains the parafovea and perifovea.

Because the macula is yellow in colour it absorbs excess light that enters the eye and acts as natural sunglasses.

It is specialized for high acuity

Visual acuity

Visual acuity is acuteness or clearness of visual perception, especially form vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
vision.

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Clinical significance

Whereas loss of peripheral vision

Peripheral vision

Peripheral vision is a part of visual perception that occurs outside the very center of gaze. There is a broad set of non-central points in the field of view that is included in the notion of peripheral vision....
may go unnoticed for some time, damage to the macula will result in loss of central vision, which is usually immediately obvious. The progressive destruction of the macula is a disease

Disease

A disease or medical condition is an abnormal condition of an organism that impairs bodily functions, associated with specific symptoms and Medical signs....
known as macular degeneration

Macular degeneration

File:Human eye cross-sectional view grayscale.pngFile:Human eyesight two children and ball normal vision.jpgFile:Human eyesight two children and ball with age-related macular degeneration.jpg...
and can sometimes lead to the creation of a macular hole. Macular holes are rarely caused by trauma, but if a severe blow is delivered perfectly it can burst the blood vessels going to the macula, destroying it.

Visual input to the macula occupies a substantial portion of the brain's visual capacity. As a result, some forms of visual field loss

Visual field

The term 'visual field' is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspection psychological experiments" , while field of view "refers to the physical objects and light sources in the external world...
can occur without involving the macula; this is termed macular sparing. (For example, visual field testing might demonstrate homonymous hemianopia with macular sparing.)

Macula

Clinical significance

See also

Additional images