The Eye
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Accessory structures of the eye
 Lacrimal apparatus
Lacrimal glands
Superior and lateral in each eye
Produces tears
Several small ducts liberate the
tear continually
Excretory ducts
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Lacrimal Apparatus
Lacrimal canal
Medial in each eye
Lacrimal sac
Nasolacrimal duct
Tears
Salt solution
Contains lysozyme and antibodies
Cleanse, protect, moisten and lubricate the
eye ball
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Accessory structures of the eye
 Palpebrae
Lateral canthus
Medial canthus
Caruncle – contains sweat and
sebaceous glands
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Accessory structures of the eye
Eyelashes
Ciliary glands
Modified sweat glands between the
eyelashes
Meibomian or tarsal glands
Posterior to the eyelashes. Secrete oil
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Accessory structures of the eye
Sty
Acute inflammation of the ciliary or
meibomian gland
Chalazio
Chronic inflammation of the meibomian
gland
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Accessory structures of the eye
 Conjunctiva
Palpebral
Ocular or bulbar
It is a mucosa that secretes mucus
Conjunctivites
Inflamation of the conjunctiva
 Extrinsic muscles of the eye
Control eye movement
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Internal Anatomy of the eye
 Outer fibrous tunic
Dense avascular connective tissue
Sclera
Cornea
Transparent, anterior most portion
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Internal Anatomy of the eye
 Middle vascular tunic (uvea)
Iris
• Colored part of the eye
• Smooth muscle acting as a diaphragm
Ciliary body
• Ciliary muscles – control the shape of
the lens
• Ciliary processes – secretes aqueous
humor
• Suspensory ligaments
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Internal Anatomy of the eye
 Choroid
Posteriormost part
Contain melanin
Tapetum lucidum (only in animals)
 Inner sensory tunic (Retina)
Pigmented layer
Covers the choroid
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Internal Anatomy of the eye
Neural layer
Rods – photoreceptors cells for dim light.
Perceives gray tones
Cones – photoreceptors cells for color.
They need high amount of light
Optic disc – blind spot. Emergency of the
optic nerve
Macula lutea – high concentration of
cones.
• Fovea
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Internal Anatomy of the eye
 Lens
Held by the suspensory ligaments. Attaches
to the ciliary body.
Catarats – lens become opaque and hard
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Internal Anatomy of the eye
 Anterior segment
Aqueous humor – clear fluid formed by the
ciliary process. It provides nutrients for the
lens and cornea.
Scleral venus sinus (canal of Schlemm) –
absorbs the aqueous humor
Glaucoma – increased intraocular pressure
 Posterior segment
Vitreous humor – helps to keep the retina in
place
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The Sectional Anatomy of the
Eye
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Figure 17.4a, b
Microscopic anatomy of the retina
 Pigmented epithelial layer
Located between the choroid and neural
layer
 Neural layer
Photoreceptors – rods and cones
Bipolar neurons
Ganglion neurons
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Microscopic anatomy of the
retina
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Visual Pathways to the brain
 Optic nerve
 Optic chiasma
It is the crossing of the fibers of the optic
nerve
 Optic tract
 Thalamus
 Optic radiation
 Visual cortex – located on the occipital lobe
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Visual Tests and Experiments
 Blind Spot
When the image fall on the optic disc
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Visual Tests and Experiments
 Refraction of the light rays
Cornea
Lens
Vitreous humor
 Accommodation of the lens
Near-point accommodation
Presbiopia – difficult focus for close
vision because of decreased lens
elasticity
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Visual Tests and Experiments
 Visual acuity
Snellen chart
Emmetropy
Myopia
Hyperopia
 Astigmatism
Irregularity in the curvatures of the lens
and/or cornea
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Visual Tests and Experiments
 Color blindness
Three cone types- red, green and blue
 Binocular vision
Three dimensional vision
Accuracy of locating objects
Depth perception
 Panoramic vision
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Visual Tests and Experiments
 Extrinsic muscles of the eye
Convergence
Medial eye movements for near vision
Keep moving objects focused on the fovea
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Visual Tests and Experiments
 Pupillary reflex
Photopupillary reflex
Constriction of the pupils when the
retina is illuminated by a bright light
Intrinsic muscles of the eye
Accommodation pupillary reflex
Change of the pupil diameter for near
focus
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Eye Dissection
WHOLE EYE
Cornea
Sclera
Optic nerve
Extrinsic muscles
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Eye Dissection
FRONTAL CUT
Humors: aqueous, vitreous
Lens
Ciliary body
Iris
Pupil
Choroid
Retina
 Posterior cavity
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