Human Anatomy & Physiology (9th Edition)

Published by Pearson
ISBN 10: 0321743261
ISBN 13: 978-0-32174-326-8

Chapter 15 - The Special Senses - Review Questions - Page 589: 32


The macula lata is small yellowish pigment spot of the retina at the posterior pole of the eyeball. When one focuses directly on an object, the rays of light go directly through the center of the pupil to the photoreceptors in the macula latata. At the center of the macula is located the fovea centralis. This central area of the macula lata is only about .06". in diameter ( about the size of a pin head). The cones are the photoreceptors that enable the sharpest focus and the most detailed vision. Most of the photoreceptors in the macula are cones. In the fovea itself all of the receptors are cones. Consequently, the fovea centralis is the area ( point) of sharpest focus, highest acuity and greatest resolution on the retina.Therefore the importance of the fovea is that if one is doing detailed work, --such as reading , microscopic work, jewelery-- or needs to see straight a head-- as in driving a motor vehicle--an intact macula lata and an undamaged fovea are essential. Certain diseases like macular degeneration, and certain kinds of trauma can damage the macula ( and fovea centralis) and impair central vision. This is a serious disability to have.

Work Step by Step

The fovea centralis in the center of the macula lata is the point (area ) of the retina that permits the sharpest focus, most acute vision, and greatest resolution of details. Therefore, if one has to do close work such as reading , jewelery, computer repair etc.,that one needs to have an intact macula lata with an undamaged fovea centralis. The fovea centralis is also important if one needs to see clearly directly ahead. Therefore the driver of a motor vehicle who has macular degeneration or any other impairment of function of macula and fovea would be at a greater risk than normal for getting into accidents because of fuzzy vision.
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