Vision

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Vision
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Anatomy of the Eye

• Fibrous tunic
• Sclera
• Cornea

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Anatomy of the Eye

• Vascular tunic Uvea
• Choroid
• Ciliary body
• Iris
• Pupil

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Anatomy of the Eye

• Nervous tunic Retina optic nerve
• Outer pigmented layer
• Nervous layer

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Photoreceptors

• Rods
• Cones
• Macula
• Fovea centralis

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• Optic Nerve
• Optic disc
• Blind Spot

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Anatomy of the Eye Miscellaneous structures

• Lens
• Anterior cavity
• Aqueous humor
• Posterior cavity
• Vitreous humor

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Anatomy Accessory structures

• Eyelids Palpebrae
• Tarsal plate
• Meibomian glands
• Palpebral fissure
• Lateral commissure
• Medial commissure
• Caruncle
• Sebaceous ciliary glands

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Anatomy Accessory structures

• Conjunctiva
• Palpebral
• Bulbar

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Anatomy Accessory structures

• Lacrimal apparatus
• Function
• Lacrimal gland
• Lacrimal puncta
• Lacrimal canal
• Nasolacrimal duct

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Vision

• Light
• Refraction
• Emmetropia Normal vision, light rays focus on a
  single point called the Focal Point

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Focal Point
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Retina
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Vision

• Accommodation
• For close vision
• Pupils constrict
• Eyeballs converge
• Near point of vision

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Vision

• Eye movement controls
• Voluntary fixation (premotor area)
• Involuntary fixation (visual area)

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Vision

• Binocular vision
• Diplopia
• Strabismus

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Photoreceptors of Vision

• Rods
• Rhodopsin is photopigment
• Numerous about 120 million
• Sensitive to light
• Relative lack of color discrimination
• Peripheral retina in location
• Good for night vision, but poor detail
• Convergence

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Photoreceptors of Vision

• Cones
• Few about 6 million
• Photopigments sensitive to differing wavelengths
  of light
• 400 nm blue
• 500 nm green
• 600 nm red

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Photoreceptors of Vision

• Cones
• High level of illumination
• Not very sensitive to light
• See in color
• Precise detail
• Little convergence
• Mostly in center of retina, esp. fovea

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Neural Components of Vision

• Bipolar neurons
• Ganglion neurons
• Lateral inhibition
• Horizontal cells
• Amacrine cells

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Visual Acuity

• Snellen Eye Chart
• 20/20

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Light/Dark Adaptation

• Photopigment concentration
• Pupillary light reflex
• PNS constricts pupil
• Direct ipsilateral
• Indirect Consensual - contralateral
• Cones inhibit rods in bright light

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Visual Pathway

• Optic Nerve
• Optic Chiasma
• Optic tracts
• Thalamus lateral geniculate body
• Occipital lobe of cerebral cortex

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