The clinical macula is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The gaze is into the camera, so in each picture the macula is in the center of the image, and the optic disc is located towards the nose. Clinical significance įundus photographs of the right eye (left image) and left eye (right image), seen from front so that left in each image is to the person's right. The macula is thus responsible for the central, high-resolution, color vision that is possible in good light and this kind of vision is impaired if the macula is damaged, for example in macular degeneration. In the fovea centralis, cones predominate and are present at high density. There is only one type of rod, but the rods are more sensitive than the cones, so in dim light, they are the dominant photoreceptors active, and without information provided by the separate spectral sensitivity of the cones it is impossible to discriminate colors. The brain combines the signals from neighboring cones to distinguish different colors. In detail, the normal human eye contains three different types of cones, with different ranges of spectral sensitivity. Within the macula are the fovea and foveola that both contain a high density of cones, which are nerve cells that are photoreceptors with high acuity. Structures in the macula are specialized for high- acuity vision. Īfter death or enucleation (removal of the eye), the macula appears yellow, a color that is not visible in the living eye except when viewed with light from which red has been filtered. A formulation of 10 mg lutein and 2 mg zeaxanthin has been shown to reduce the risk of age-related macular degeneration progressing to advanced stages, although these carotenoids have not been shown to prevent the disease. There is some evidence that these carotenoids protect the pigmented region from some types of macular degeneration. Zeaxanthin predominates at the macula, while lutein predominates elsewhere in the retina. The yellow color comes from its content of lutein and zeaxanthin, which are yellow xanthophyll carotenoids, derived from the diet. The retina's receptor layer contains two types of photosensitive cells, the rod cells and the cone cells.īecause the macula is yellow in color, it absorbs excess blue and ultraviolet light that enter the eye and acts as a natural sunblock (analogous to sunglasses) for this area of the retina. It is a small pit that contains the largest concentration of cone cells. The fovea is located near the center of the macula. The umbo is the center of the foveola which in turn is located at the center of the fovea. The anatomical macula is defined histologically in terms of having two or more layers of ganglion cells. The anatomical macula at 5.5 mm (0.22 in) is much larger than the clinical macula which, at 1.5 mm (0.059 in), corresponds to the anatomical fovea. Īn even smaller central region of highest receptor density (40–80 μm) is sometimes referred to as the foveal bouquet. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. Its center is shifted slightly away from the optical axis (laterally, by 5°=1.5 mm). The macula is an oval-shaped pigmented area in the center of the retina of the human eye and other animal eyes. Schematic diagram of the macula lutea of the retina, showing perifovea, parafovea, fovea, and clinical macula
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