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EYE AND VISION Pedro Amarante Andrade, PhD LCSC06 BIOSCIENCES FOR SPEECH AND LANGUAGE THERAPY LCSC06 | Biosciences for SLT VISION: THE EYE Location Size Shape Colour Texture Direction Speed LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT ANATOMY LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT RETINA Five types of neurons: • • • • • Photoreceptors; Bipolar; Ganglion; Horizontal; Amecrine Neuroscience, Third Edition. 2004. Purves et al pp. 235 LCSC06 | Biosciences for SLT RETINA Five types of neurons: • Photoreceptors; – Outer layer; Neuroscience, Third Edition. 2004. Purves et al pp. 235 LCSC06 | Biosciences for SLT RETINA Human Physiology, An integrated approach, 5th edition Dee Unglaud Silverthorn LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT VISUAL PATHWAY Tortora G.J. and Derricskon B. 2012. Principles of Anatomy and Physiology . pp. 619 LCSC06 | Biosciences for SLT 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 LCSC06 | Biosciences for SLT 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
