AskDefine | Define macula

Dictionary Definition

macula

Noun

1 a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field [syn: sunspot]
2 a yellowish central area of the retina that is rich in cones and that mediates clear detailed vision [syn: macula lutea, macular area, yellow spot]
3 a patch of skin that is discolored but not usually elevated; caused by various diseases [syn: macule] [also: maculae (pl)]

User Contributed Dictionary

English

Noun

  1. An oval yellow spot near the center of the retina of the human eye, histologically defined as having two or more layers of ganglion cells, responsible for detailed central vision.
  2. A spot, as on the skin, or on the surface of the sun or of some other luminous orb.
  3. A rather large spot or blotch of color.
  4. In planetary geology, an unusually dark area on the surface of a planet or moon.

Related terms

oval yellow spot near the center of the retina

Translations

A blot or splotch

Italian

Latin

Noun

  1. A spot or a stain.
maculā

Inflection

Extensive Definition

The macula or macula lutea (from Latin macula, "spot" + lutea, "yellow") is an oval yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells. Near its center is the fovea, a small pit that contains the largest concentration of cone cells in the eye and is responsible for central vision.
It is specialized for high acuity vision. Within the macula are the fovea and foveola which contain a high density of cones (photoreceptors with high acuity). In contrast to the rest of the retina, which is supplied by the retinal artery, the macula receives its blood supply from the choroid.

Clinical significance

Whereas loss 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 known as macular degeneration and leads 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 can occur without involving the macula; this is termed macular sparing. (For example, visual field testing might demonstrate homonymous hemianopsia with macular sparing.) This finding can be very informative for the ophthalmologist.

Additional images

macula in Bengali: ম্যাকুলা
macula in German: Gelber Fleck (Auge)
macula in Estonian: Kollatähn
macula in Modern Greek (1453-): Ωχρή κηλίδα
macula in Spanish: Mácula
macula in French: Macula
macula in Italian: Macula (oculistica)
macula in Lithuanian: Geltonoji dėmė
macula in Dutch: Gele vlek
macula in Norwegian: Macula lutea
macula in Polish: Plamka żółta
macula in Portuguese: Mácula
macula in Russian: Жёлтое пятно
macula in Simple English: Yellow spot
macula in Swedish: Gula fläcken
macula in Turkish: Sarı benek
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