Transcript Eye and Vision File

EYE AND VISION
Pedro Amarante Andrade, PhD
LCSC06
BIOSCIENCES
FOR SPEECH AND LANGUAGE THERAPY
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VISION: THE EYE
Location
Size
Shape
Colour
Texture
Direction
Speed
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VISION: THE EYE
“More than half of the sensory
Size
receptors in the
human body are
located in theShape
eyes, and a large
part of the Colour
cerebral cortex is
devoted to processing visual
Texture
information”
Direction
Tortora G.J. and Derricskon B. 2012. Principles of
Anatomy and Physiology . pp. 604
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ANATOMY
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ANATOMY
• Lens and Cornea
remarkable level of
transparency for
organic structures
that rivals inorganic
materials such as
glass
Neuroscience, Third Edition. 2004. Purves et al pp. 230
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ANATOMY
• Fluid-filled sphere
• Three layers:
– Retina (Neurons)
– Choroid (blood sup.)
• Ciliary muscle
• Iris (adjust the pupil)
– Sclera (outermost –
fibrous tissue,
becomes the cornea)
Neuroscience, Third Edition. 2004. Purves et al pp. 230
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ANATOMY
Liquid
• Fluid-filled sphere
• Anterior chamber:
– Aqueous chamber
• Posterior chamber:
– Fluid is produced by
the ciliary process
and flows into the
anterior chamber
through the pupil
Neuroscience, Third Edition. 2004. Purves et al pp. 230
• Cells in Limbus region
(drainage of liquid)
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 609
LCSC06 | Biosciences for SLT
ANATOMY
Liquid
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 609
LCSC06 | Biosciences for SLT
ANATOMY
• Fluid-filled sphere
• Behind the lens:
Liquid
– Vitreous humor
• 80% of total volume
• Maintain the eye
shape
• Contain phagocytic
cells that remove
blood and debris
Neuroscience, Third Edition. 2004. Purves et al pp. 230
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IMAGE FORMATION
Refraction
Cornea and
lens are
responsible for
focusing the
image in the in
the retina
Neuroscience, Third Edition. 2004. Purves et al pp. 231
Neuroscience, Third Edition. 2004. Purves et al pp. 232
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 615
LCSC06 | Biosciences for SLT
IMAGE FORMATION
Refraction
Cornea and
lens are
responsible for
focusing the
image in the in
the retina
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 615
LCSC06 | Biosciences for SLT
IMAGE FORMATION
Accomodation
Far away
objects
Nearby
objects
Neuroscience, Third Edition. 2004. Purves et al pp. 231
Adjustments on the size of Pupil
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RETINA
Part of
the
CNS
Neuroscience, Third Edition. 2004. Purves et al pp. 230
LCSC06 | Biosciences for SLT
RETINA
Part of
the
CNS
Neuroscience,
Third Edition. 2004.
Purves et al pp. 235
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RETINA
Five types of neurons:
•
•
•
•
•
Photoreceptors;
Bipolar;
Ganglion;
Horizontal;
Amecrine
Neuroscience, Third Edition. 2004. Purves et al pp. 235
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RETINA
Five types of neurons:
• Photoreceptors;
– Outer layer;
Neuroscience, Third Edition. 2004. Purves et al pp. 235
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RETINA
Human Physiology, An integrated approach, 5th edition
Dee Unglaud Silverthorn
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RETINA
Five types of neurons:
• Photoreceptors;
• Bipolar;
Neuroscience, Third Edition. 2004. Purves et al pp. 235
LCSC06 | Biosciences for SLT
RETINA
Five types of neurons:
• Photoreceptors;
• Bipolar;
• Ganglion;
Neuroscience, Third Edition. 2004. Purves et al pp. 235
LCSC06 | Biosciences for SLT
RETINA
Five types of neurons:
•
•
•
•
Photoreceptors;
Bipolar;
Ganglion;
Horizontal;
• Amecrine
Neuroscience, Third Edition. 2004. Purves et al pp. 235
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RETINA
Rods and Cones
Rods
LOW spatial resolution
Very Sensitive to light
Cones
HIGH spatial resolution
Insensitive to light
Neuroscience, Third Edition. 2004. Purves et al pp. 241
LCSC06 | Biosciences for SLT
RETINA
Rods and Cones
Rods
LOW spatial resolution
Very Sensitive to light
Scotopic vision
• At the lowest level of
light;
• Low resolution and no
colour
Neuroscience, Third Edition. 2004. Purves et al pp. 241
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RETINA
Rods and Cones
Photopic vision
• Dominant in
determining what is
seen in light
Cones
HIGH spatial resolution
Insensitive to light
Neuroscience, Third Edition. 2004. Purves et al pp. 241
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ELECTROMAGNETIC RADIATION
Energy is the form of waves that radiates from
the sun;
White objects
reflect all
wavelengths
Black objects
absorb all
wavelengths
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 605
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VISUAL PATHWAY
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and Physiology . pp. 619
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VISUAL PATHWAY
Neuroscience, Third Edition. 2004. Purves et al pp. 261
LCSC06 | Biosciences for SLT
VISUAL PATHWAY
Neuroscience, Third Edition. 2004. Purves et al pp. 268
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VISUAL PATHOLOGIES
CATARACTS
A common cause of blindness is a loss of
transparency of the lens known as a cataract (CAT-arakt waterfall). The lens becomes cloudy (less
transparent) due to changes in the structure of the
lens proteins. Cataracts often occur with aging but
may also be caused by injury, excessive exposure to
ultraviolet rays, certain medications (such as longterm use of steroids), or complications of other
diseases (for example, diabetes). People who smoke
also have increased risk of developing cataracts.
Fortunately, sight can usually be restored by surgical
removal of the old lens and implantation of a new
artificial one.
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 636
LCSC06 | Biosciences for SLT
VISUAL PATHOLOGIES
GLAUCOME
Glaucoma is an abnormally high intraocular pressure
due to a build-up of aqueous humor within the
anterior cavity. The fluid compresses the lens into the
vitreous body and puts pressure on the neurons of
the retina. Persistent pressure results in a progression
from mild visual impairment to irreversible
destruction of neurons of the retina, damage to the
optic nerve, and blindness. Glaucoma is painless, and
the other eye compensates largely, so a person may
experience considerable retinal damage and loss of
vision before the condition is diagnosed.
Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and
Physiology . pp. 636
LCSC06 | Biosciences for SLT