Fovea: Perbedaan antara revisi

Parafovea adalah sabuk tempat sel [[ganglion]] terbentuk dengan jumlah lebih dari lima baris sel, juga bagian sel kerucut yang memiliki densitas paling tinggi. Parafovea memiliki 50 sel kerucut per 100 mikrometer, pada manusia parafovea memiliki jarak 1¼ mm dari pusat fovea.

 

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The fovea is responsible for sharp central [[Visual perception|vision]] (also called [[foveal]] vision), which is necessary in humans for [[reading (activity)|reading]], watching, driving, and any activity where visual detail is of primary importance. The fovea is surrounded by the ''parafovea'' belt, and the ''perifovea'' outer region.<ref name=IOVSnomen/> The parafovea is the intermediate belt, where the [[ganglion]] cell layer is composed of more than five rows of cells, as well as the highest density of cones; 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. The perifovea contains an even more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most central fovea. This, in turn, is surrounded by a larger [[peripheral vision|peripheral]] area that delivers highly compressed information of low resolution. Approximately 50% of the nerve fibers in the [[optic nerve]] carry information from the fovea, while the other 50% carry information from the rest of the retina. The parafovea extends to a distance of 1¼ mm from the central fovea, and the perifovea is found 2¾ mm away from the fovea centralis.<ref>"eye, human."Encyclopædia Britannica. 2008. [[Encyclopædia Britannica 2006 Ultimate Reference Suite DVD]]</ref>