PSY 368 Chapter Notes - Chapter 2: Ciliary Muscle, Spectral Sensitivity, Amacrine Cell
3 Mar 2019
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Document Summary
When we look directly at an object, the object"s image falls on the fovea: the peripheral retina, which includes all of the retina outside of the fovea, contains both rods and cones. It is important to note that although the fovea has only cones, there are also many cones in the peripheral retina. The fovea is so small that is contains only about 1% of the 6 million cones in the retina: the peripheral retina contains many more rods than cones. In retinitis pigmentosa, the peripheral retina initially degenerates and causes loss of vision in the periphery. This enables the receptor"s ganglion cell fibers to flow into the optic nerve. The absence of receptors in this area creates the blind spot: the blind spot is located off to the side of our visual field, where objects are usually not in sharp focus. We usually don"t notice it: a mechanism in the brain fills in the place where the image disappears.
