Biomedical Engineering Reference
In-Depth Information
Fovea
(a)
Fovea
(b)
FIGURE 13.3 (A) Side view of the eye. The rear surface of the eye is called the retina. The retina is part of the
central nervous system and consists of two photoreceptors: rods and cones. (B) Front view looking at the rear
inside surface (retina) of the eye. The fovea is located centrally and is approximately 1 mm in diameter. The oculo-
motor system maintains targets centered on the fovea.
the central one-half degree region of the retina, known as the fovea. Lining the retina are
photoreceptive cells that translate images into neural impulses. These impulses are then
transmitted along the optic nerve to the central nervous system via parallel pathways to
the superior colliculus and the cerebral cortex. The fovea is more densely packed with
photoreceptive cells than the retinal periphery—thus a higher-resolution image (or higher
visual acuity) is generated in the fovea than the retinal periphery. The purpose of the fovea
is to allow us to
clearly
see an object, and the purpose of the retinal periphery is to allow us
to
a new object of interest. Once a new object of interest is detected in the periphery,
the system redirects the eyes to the new object.
One of the most successfully studied systems in the human is the oculomotor or eye
movement system. Some of the reasons for this success are the relative ease in obtaining
data, the simplicity of the system, and the lack of feedback during dynamic changes in
the system. A saccade is a fast eye movement that involves quickly moving the eyes from
detect
Search WWH ::




Custom Search