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Exam 6 - Lecture 3

Quiz yourself by thinking what should be in each of the black spaces below before clicking on it to display the answer.
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Answer
Top 5 Causes of Blindness (Worldwide):   1. Cataracts 2. Glaucoma 3. Macular Degeneration 4. Corneal Opacity 5. Diabetic Retinopathy Eye Structure consists of:  
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Accessory Structures of the Eye   Palpebrae, Palpebral Fissure, Lateral/Medial Canthus (where the top and the bottom eyelids are connected at the outer/inner corners of the eye), Eyelashes, Glands, Conjunctiva (epithelial covering of the inside of the eyelid and outside of eyeball)  
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Palpebrae   Eyelid (physical barrier, continuous with skin)  
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Palpebral Fissure   Space between the eyelids  
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Lateral/Medial Canthus   Where the top and the bottom eyelids are connected at the outer/inner corners of the eye  
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Eyelashes   Physical barrier of the eye  
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Glands of the Eye   Lacrimal (tear), Tarsal (Mebomian), Sweat  
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Location of Lacrimal Gland   Superior and lateral to the eye  
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Location of Tarsal Gland   Inside of eyelids (produce Mebomian – a lipid-rich secretion)  
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Location of Sweat Glands (eye)   Between eyelash follicles (produce sweat)  
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Functions of Glands (of the eye)   Lubricate eye, prevent evaporation, antibacterial and antifungal properties  
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Conjunctiva   Epithelial covering of the inside of the eyelid (Palpebral) and outside of eyeball (Ocular)  
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Location of Palpebral Conjunctiva   Inside of eyelids  
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Location of Ocular Conjunctiva   Outside of eyeball  
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Two types of Gland infections:   1. Chalazion (inflamed Tarsal gland) 2. Sty (infected Tarsal gland)  
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Chalazion   Inflamed Tarsal gland; Painless; Lasts for a month  
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Sty   Infected Tarsal gland; Painful; Lasts for days  
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Treatment for Chalazion and Sty   Warm compress, lance; if infected – topical antibiotics  
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Conjunctivitis   Pink Eye; Inflammation of the Conjunctiva; Itching, burning, watery; Bacterial or viral (highly contagious); Chemical, allergy, physical  
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Symptoms of Conjunctivitis   Itching, burning, watery eyes  
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Conjunctivitis can be _______ or ________ and can be due to _________, __________, or __________.   Bacterial or viral; Due to chemical, allergy, or physical  
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Treatment for Conjunctivitis   No contact lenses; Warm, moist compress; Time; Bacterial give antibiotics (drops or ointment); Allergic give anti-inflammatory or antihistamines  
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What types of antibiotics do you give for Bacterial Conjunctivitis?   Drops or ointment  
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Lacrimal Apparatus   Structures of the eye that produce, distribute, store, and remove tears – Lacrimal Gland and Ducts, Lacrimal Caruncle, Lacrimal Punctum, Lacrimal Canaliculus, Lacrimal Sac, Nasolacrimal Duct  
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The secretions of the Lacrimal Gland:   Provide nutrients and oxygen to corneal cells, Contain lysozymes and antibiotics  
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The Lacrimal Gland produces about ___mL per day   1 mL  
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Secretions of the ____________ provide nutrients and oxygen to corneal cells   Lacrimal Glands  
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Function of Lacrimal Gland and Ducts   Produces and delivers tears to the eye (about 1 mL per day)  
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Lacrimal Caruncle   Glandular tissue near Medial Canthus; Tears pool here (Lacrimal Lake)  
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Where do tears pool?   Lacrimal Caruncle (Lacrimal Lake)  
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Lacrimal Punctum   Pores that drain tears from Lacrimal Caruncle into Lacrimal Canaliculi  
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Lacrimal Canaliculus   Drainage ducts to Lacrimal Sac  
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Lacrimal Sac   Temporary storage of Lacrimal secretions  
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Nasolacrimal Duct   Drainage of secretions into nose  
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Anterior Cavity of the Eye is filled with:   Aqueous Humor  
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Aqueous Humor is produced by:   The Ciliary Processes  
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The Ciliary Processes secrete Aqueous Humor at the rate of ____ micro liters a minute   1-2 micro liters per minute  
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Functions of Aqueous Humor   It is watery like the CSF; Responsible for nutrient and waste transport; Fluid cushion  
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Location of the Anterior Chamber   Cornea to the Iris  
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Anterior Cavity of the Eye is divided into:   The Anterior Chamber (from Cornea to Iris) and the Posterior Chamber (Iris to the Ciliary Body and Lens)  
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Location of the Posterior Chamber   Iris to the Ciliary Body and Lens  
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Posterior Cavity of the Eye is filled with:   Vitreous Body  
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Vitreous Body is produced when?   In Utero (not regenerated once you are grown)  
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Properties of Vitreous Body   Collagen and proteoglycan rich  
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Function of Vitreous Body   Helps maintain the shape of the eye  
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Flow of Aqueous Humor:   Produced in Posterior Cavity (Vitreous Chamber) → Flows into Anterior Cavity through Pupil → Drains through Canal of Schlemm → Enters the veins in Sclera  
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Canal of Schlemm   Drains Aqueous Humor into the veins in the Sclera  
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___% of the U.S. population has Glaucoma   1-2%  
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Glaucoma is the ___% worldwide cause of blindness (number 2)   12%  
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Glaucoma occurs in people > ____ years, especially people >____ years   35, 65  
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Glaucoma   Increased intraocular pressure due to Aqueous Humor not draining properly; Results in damage to the optic nerve which changes action potentials; Can lead to blindness if untreated  
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Sclera is _________, not like a balloon   Fibrous  
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What is the weakest part of the Sclera?   Optic Disc  
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What does distorting the Optic Nerve do?   Causes changes in action potentials which can lead to blindness  
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Topical Treatment for Glaucoma   Beta-Blockers (decrease Aqueous Humor production) and Muscarinic Agonists (constrict the pupil which increases drainage)  
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How do topical Beta-Blockers treat Glaucoma?   They decrease production of Aqueous Humor  
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How do topical Muscarinic Agonists treat Glaucoma?   They constrict the pupil which increases drainage  
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Surgical Treatment for Glaucoma   Repeatedly perforateing the wall of the Anterior Chamber, which increases drainage  
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Three Layers of the Eye   1. Fibrous Tunic 2. Vascular Tunic 3. Neural Tunic  
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Fibrous Tunic   The layer of the Eye responsible for support and protection; Attachment site for extrinsic muscles; Assists in focusing  
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Which layer of the Eye is the attachment site for extrinsic muscles?   Fibrous Tunic  
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Which layers of the Eye are responsible for focusing?   Vascular Tunic and Fibrous Tunic (assists)  
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Which layer of the Eye is for support and protection?   Fibrous Tunic  
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The Fibrous Tunic is made up of what structures?   Cornea, Limbus, Sclera  
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Vascular Tunic   Blood and lymphatic connection; Regulates light entering the eye; Homeostasis of Aqueous Humor; Focusing  
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Which layer of the Eye is the blood and lymphatic connection?   Vascular Tunic  
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Which layer of the Eye regulates light entering the Eye?   Vascular Tunic  
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Which layer of the Eye is responsible for the homeostasis of the Aqueous Humor?   Vascular Tunic  
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The Vascular Tunic is made up of what structures?   Ciliary Body, Ciliary Process, Iris, Choroid  
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Neural Tunic   Detects light and color; Relays visual information to Brain  
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Which layer of the Eye detects light and color?   Neural Tunic  
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Which layer of the Eye relays visual information to the Brain?   Neural Tunic  
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The Neural Tunic is made up of what structures?   Ora Serrata, Retina  
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Sclera   White of the Eye; Dense connective tissue (collagen and elastic fibers); Insertion point of the extrinsic Eye muscles; Small blood vessels; Anterior surface covered with the Ocular Conjunctiva  
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What type of tissue is the Sclera?   Dense connective tissue (collagen and elastic fibers)  
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What is the thickest part of the Sclera?   The posterior  
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What is the thinnest part of the Sclera?   The anterior  
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What is the insertion point of the extrinsic Eye muscles?   Sclera  
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What is the anterior surface of the Sclera is covered with?   Ocular Conjunctiva  
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Limbus   Border between Cornea and Sclera  
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Cornea   Continuous with Sclera, BUT is made of collagen fibers; Transparent; No blood vessels; Covered with corneal epithelium; Continuous with but distinct from the Ocular Conjunctiva; Many nerve endings  
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What type of tissue is the Cornea made of?   Collagen fibers (transparent)  
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The Sclera has ___________ but the Cornea has none   Blood Vessels  
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The Cornea is covered with corneal epithelium which is continuous with, but distinct from, the __________.   Ocular Conjunctiva  
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Iris   Colored part of the eye; Contains blood vessels and melanocytes; Have Pupillary Muscles that constrict or dilate the Pupil  
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A lack of melanocytes in the Iris makes it what color?   Blue, Gray  
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An abundance of melanocytes in the Iris makes it what color?   Green, Brown, Black  
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Two Pupillary Muscles   1. Constrictor (Concentric) – contraction leads to decreased Pupil size 2. Dilator (Radial) – contraction leads to increased Pupil size  
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Contraction of the Constrictor (Concentric) Pupillary Muscles leads to __________ Pupil size   Decreased  
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Contraction of the Dilator (Radial) Pupillary Muscles leads to ____________ Pupil size   Increased  
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Location of the Choroid   Lies between Fibrous and Neural Tunics in the posterior portion of the Eye (posterior to the Ora Serrata)  
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Functions of the Choroid   Delivers oxygen and nutrients to the Retina; Contains melanocytes (particularly near the Sclera) that keep extra light out  
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What delivers oxygen and nutrients to the Sclera?   Choroid  
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Ciliary Body is composed of:   Ciliary Muscles and Ciliary Processes (Suspensory Ligaments aid these structures)  
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Functions of Ciliary Body   Connects the Iris to the Choroid  
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What type of tissue is the Ciliary Body made of?   Epithelia-covered Muscle Tissue  
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Ciliary Muscle   Sphincter muscle; Contraction of the muscle leads to relaxation of Suspensory Ligaments on Lens; Relaxation of the muscle leads to tension in Suspensory Ligaments on Lens  
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Contraction of the Ciliary Muscle leads to ____________ of the Suspensory Ligaments on the Lens   Relaxation  
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Relaxation of the Ciliary Muscle leads to ____________ in the Suspensory Ligaments on the Lens   Tension  
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Ciliary Processes   Folds of epithelia that cover the Ciliary Muscle; Secrete Aqueous Humor  
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What covers the Ciliary Muscle?   Ciliary Processes  
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Suspensory Ligaments   Attach the Lens to the Ciliary Process; Holds Lens in place behind Pupil  
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What attaches the Lens to the Ciliary Processes?   Suspensory Ligaments  
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What holds the Lens in place behind the Pupil?   Suspensory Ligaments  
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Two Layers of the Retina   1. Neural Layer 2. Pigmented Layer  
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Neural Layer of the Retina   Thick inner layer; Light passes through; Contains Photoreceptors, supporting cells, and neurons; Preliminary processing of information; Extends to the Ora Serrata  
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Which layer of the Retina is thicker?   Neural Layer  
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Which layer of the Retina does light pass through?   Neural Layer  
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Which layer of the Retina contains Photoreceptors?   Neural Layer  
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The Neural Layer of the Retina extends to the ____________.   Ora Serrata  
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Pigmented Layer of the Retina   Thin outer layer; Contains melanocytes; Absorbs light; Close proximity to the neural part; Extends over Ciliary Body and Iris  
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Which layer of the Retina is thinner?   Pigmented Layer  
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Which layer of the Retina is the inner layer?   Neural Layer  
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Which layer of the Retina is the outer layer?   Pigmented Layer  
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Which layer of the Retina contains melanocytes?   Pigmented Layer  
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Which layer of the Reina absorbs light?   Pigmented Layer  
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The Pigmented Layer of the Retina extends of the ___________ and the ___________.   Ciliary Body and Iris  
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Red Reflex   Shining a light into your eye should result in glowing, red eyes  
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Glowing animal eyes are due to:   The Tapetum Lucidum (highly reflective layer behind the Retina that aids with night vision)  
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Tapetum Lucidum   A highly reflective layer behind the Retina in animals that aids with night vision  
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The good of having a Tapetum Lucidum:   Better vision in low light conditions  
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The bad of having a Tapetum Lucidum:   Poorer vision in high light conditions  
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Eye vasculature is extremely fragile and can help with early detection of:   Neurovascularization, Arterosclerosis, Hypertension  
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Detaches Retina   Retinal tear allows Vitreous Body to seep between the Neural and Pigmented Layers  
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Symptoms of a detached Retina:   Flashes, Floaters, Curtains  
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Causes of a detached Retina:   Age, Glaucoma, Head trauma, Genetics, Diabetes, Myopia  
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Treatment for a detached Retina:   Heat or freeze the tear (although the scar tissue will be a blind spot); Inject air into Posterior Cavity  
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What will heating of freezing a retinal tear cause?   Scar tissue which is a blind spot  
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Diabetic Retinopathy affects ___% of diabetics (who are diabetic for > 15 years)   80%  
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Diabetic Retinopathy causes ___% of worldwide blindness (number 5)   5%  
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___________ damages the blood vessels in the Retina which causes Diabetic Retinopathy   Hyperglycemia  
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Damage to blood vessels in the Retina leads to leakage of ________ and/or _________ into the Posterior Cavity   Blood and/or Lipids  
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Diabetic Retinopathy   Hyperglycemia damages blood vessels in Retina; Blood and/or lipids leak into Posterior Cavity; Deprivation of vital nutrients to Retina; Angiogenesis (growth of blood vessels) into space between Neural and Pigmented Layers  
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Symptoms of Diabetic Retinopathy   Transient blurred vision, Floaters, Loss of vision (blind spots, loss of color), Blindness  
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Treatment of Diabetic Retinopathy   Vitrectomy (removal of some or all of the Vitreous Humor), Cauterize blood vessels, Corticosteroid injections  
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Location of Photoreceptors   Located in Neural Layer but loosely embedded in Pigmented Layer  
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Types of Photoreceptors   1. Rods (Detect light) 2. Cones (Color vision)  
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Function of Rods   Detect light (photons); Can function in dim light  
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Function of Cones   Color vision (wavelength of photons); Need more light, sharper image  
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Accessory Neurons in the Neural Layer of Retina   Bipolar Cells, Ganglion Cells, Horizontal and Amacrine Cells  
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Function of Bipolar Cells   Synapse with Rods and Cones  
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Function of Ganglion Cells   Synapse with Bipolar Cells; Axons form Optic Nerve  
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The Optic Nerve is made of axons from which cells?   Ganglion Cells  
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Function of Horizontal Cells   Connect the synapses of Photoreceptors and Bipolar Cells; Stimulate or inhibit communication between them; Play an important role in adjusting to a dim or brightly lit environment  
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Function of Amacrine Cells   Connect the synapses of Bipolar Cells and Ganglion Cells; Stimulate of inhibit communication between them; Play an important role in adjusting to a dim or brightly lit environment  
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Which cells connect the synapses of Photoreceptors and Bipolar Cells?   Horizontal Cells  
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Which cells connect the synapses of Bipolar Cells and Ganglion Cells?   Amacrine Cells  
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Which cells play an important role in adjusting to a dim or brightly lit environment?   Horizontal Cells and Amacrine Cells  
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Features of the Retina:   Optic Disc, Macula (Lutea), Fovea (Centralis)  
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Optic Disc   The place where axons from 1 million ganglia converge; Origin of Optic Nerve (Cranial Nerve II); Retinal Artery and Vein enter eye here; No Photoreceptors (blind spot)  
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What is the origin of the Optic Nerve (Cranial Nerve II)?   Optic Disc  
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Where do the Retinal Artery and Vein enter the Eye?   Optic Disc  
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What is the spot on the Retina called that has no Photoreceptors (Blind Spot)?   Optic Disc  
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How many axons from ganglia converge at the Optic Disc?   1 million  
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Macula (Lutea)   Visual image arrives here after it passes through the Cornea and Lens; About 6 million Cones but 0 Rods  
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Where does the visual image go after it passes through the Cornea and the Lens?   Macula (Lutea)  
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How many Cones are at the Macula (Lutea)?   About 6 million  
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How many Rods are at the Macula (Lutea)?   Zero  
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Fovea (Centralis)   Center of Macula; Greatest concentration of Cones; Sharpest vision  
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What is the center of the Macula called?   Fovea (Centralis)  
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Where is the greatest concentration of Cones found?   Fovea (Centralis) – responsible for sharpest vision  
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Retinitis Pigmentosa   Most common inherited visual abnormality; Visual pigments of discs are abnormal; Gradual destruction of Photoreceptors  
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What is the most common visual abnormality?   Retinitis Pigmentosa (1:3000)  
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How many different genes have been identified as being linked to Retinitis Pigmentosa?   35 different genes  
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What is the ratio of children born with Retinitis Pigmentosa?   1:3000  
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How many mutations in Rhodopsin have been found in Retinitis Pigmentosa?   100  
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Symptoms of Retinitis PIgmentosa   Night blindness → Tunnel vision → Blindness  
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Retinitis Pigmentosa progresses from ________ to _________.   Childhood to 40s  
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Treatment for Retinitis Pigmentosa   Vitamin A can slow the progression  
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Macular Degeneration   Leading cause of blindness in the U.S. (> 50 yrs); Neural Tunic components may separate; Loss of central vision around Fovea; Blindness (especially if “dry”)  
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What is the leading cause of blindness in the U.S.?   Macular Degeneration  
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Macular Degeneration is responsible for __% of blindness cases worldwide (number 3)   9%  
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Types of Macular Degeneration   ”Dry” and “Wet”  
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“Dry” Macular Degeneration   Cellular debris (damaged photoreceptors, etc) build up around Fovea and surrounding Macula; Loss of Photoreceptors in Macula; Less damaging, but no treatment (antioxidants slow it)  
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“Wet” Macular Degeneration   Abnormal vascular growth at Macula; Bleeding, leaking, and scarring which causes damage to Photoreceptors; Treatment is laser surgery, Avastin (anti-VEGF [vascular endothelial growth factor] = anti-angiogenesis)  
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___% of Macular Degeneration is the “Dry” type   85%  
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___% of Macular Degeneration is the “Wet” type   15%  
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Which type of Macular Degeneration is less damaging?   ”Dry”  
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Which type of Macular Degeneration has no treatment?   ”Dry”  
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Which type of Macular Degeneration results in a loss of Photoreceptors at the Macula?   ”Dry”  
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Which type of Macular Degeneration involves abnormal vascular growth at the Macula?   ”Wet”  
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Which type of Macular Degeneration is more likely to result in blindness?   ”Dry”  
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Treatment for “Wet” Macular Degeneration   Laser surgery; Avastin (anti-VEGF = anti-angiogenesis)  
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Avastin   Anti-VEGF (vascular endothelial growth factor) = anti-angiogenesis; used to treat “Wet” Macular Degeneration  
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Photoreceptors are made up of:   Outer Segments of Neural Part (which contains Discs), Inner Segment of Neural Part, Synaptic Terminal  
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Discs   Part of Photoreceptors (in the Outer Segment of Neural Part): Contain visual pigments that absorb photons (Retinal and Opsin); Rod discs have more pigment, which means they have greater photosensitivity  
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Where are the visual pigments that absorb photons located?   Discs (part of Photoreceptors)  
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What two pigments absorb photons?   Retinal (molecule derived from Vitamin A) and Opsin (Protein)  
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Retinal   Visual pigment that is derived from Vitamin A; Found in Discs in Photoreceptors  
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Opsin   Visual pigment that is a protein; Found in Discs in Photoreceptors  
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Which type of Photoreceptors have more pigment (dominant Photoreceptor)?   Rods: greater photosensitivity  
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Outer Segment of Neural Part   Part of Photoreceptor that contains Discs; Old Discs are phagocytized by pigment epithelium cells of the Pigmented Layer (they recycle Retinal)  
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Why don’t you have to do tissue matching when doing Cornea transplants?   Because there are no blood vessels there that would bring in white blood cells  
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Where is Retinal recycled?   In the Outer Segment of Neural Part  
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Inner Segment of Neural Part   Contains organelles and metabolic machinery; Photopigment synthesis  
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Where does photopigment synthesis occur?   Inner Segment of Neural Part  
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Synaptic Terminal   The place where Photoreceptors synapse with Bipolar Cells; Photoreceptors release neurotransmitters  
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Where do Photoreceptors release neurotransmitters?   Synaptic Terminal  
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How many Rods are in the Eye?   125 million  
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How many Cones are in the Eye?   6 million  
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Where are the Rods predominantly located?   Periphery of the Retina  
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Rods are responsible for ________ vision   Achromatic (non-color) vision  
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Where are Cones predominantly located?   Macula Lutea and particularly in the Fovea  
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Cones are responsible for ________ vision   Color vision  
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Achromatic vision is Retinal + __________   Rhodopsin  
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Color vision is Retinal + __________   Photopsin (SWS2 = blue, MWS = green, LWS = red)  
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___% of Cones are Blue Cones   16%  
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___% of Cones are Green Cones   10%  
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___% of Cones are Red Cones   74%  
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Blue Cones are Retinal + ____ Photopsin   SWS2  
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Green Cones are Retinal + ____ Photopsin   MWS  
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Red Cones are Retinal + ____ Photopsin   LWS  
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Color Blindness   Sex-linked recessive disease; Varying types, depending on which Opsins have decreased sensitivity or complete absence  
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___________ variants are more common than ___________ variants   Red/Green are more common than Blue  
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___% of Males are Colorblind   10%  
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___% of Females are Colorblind   < 1%  
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Photoreceptrion in Darkness   Converts photons into electrical energy; “Resting” membrane potential of Photoreceptors is -40mV  
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What is the “Resting” membrane potential of Photoreceptors in the dark?   -40mV  
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What happens in the Outer Segment in the dark?   Na+ channels are open, Na+ enters Outer Segment; cGMP opens gated Na+ channels  
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What happens in the Inner Segment in the dark?   Continuously pumps Na+ out  
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Dark Current   Movement of Na+ ions  
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What happens at the Synaptic Terminal in the dark?   Depolarization and release of Glutamate  
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A photon strikes the retinal portion of an _________ molecule in a Disc   Opsin  
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Photon converts ______ Retinal to ______ Retinal   11-cis Retinal to 11-trans Retinal  
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Once 11-cis Retinal is converted by a photon to 11-trans Retinal, Opsin activates ________ (G-Protein) which then activates ____________.   Opsin activates Transducin (G-Protein) which then activates Phosphodiesterase (PDE)  
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Phosphodiesterase (PDE)   Activated by Transducin; Converts cGMP (which opens Na+ channels in the Outer Segment) to GMP which causes the Na+ channels to close → Decrease in Na+ entering the Outer Segment  
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PDE converting cGMP to GMP causes:   Gated Na+ channels to close → Decrease in Na+ entering the Outer Segment  
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Na+ is pumped out of the __________ Segment even in light   Inner  
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Na+ being pumped out of the Inner Segment reduces _________ and causes hyperpolarization of the Photoreceptor (___ mV) which decreases Glutamate release   Reduces dark current; -70 mV  
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Hyperpolarization of a Photoreceptor makes the membrane potential of the Photoreceptor ___ mV   -70 mV  
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Na+ being pumped out of the Inner Segment results in ___________ Glutamate release   Decreased  
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What kind of cells signal that a photon was detected?   Bipolar Cells  
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Does Retinal spontaneously revert back to 11-cis form?   No, ATP is required to convert it back  
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Photoreceptors can’t respond to subsequent photons until _____________ molecules regenerate   Rhodopsin/Photopsin  
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Rhodopsin/Photopsin is composed of:   Retinal + Opsin  
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____ is required to convert 11-trans Retinal back to 11-cis Retinal   ATP  
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____ levels gradually build up during the recovery period due to inactive Opsin and dark current is reestablished   cGMP  
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Bleaching   When Photoreceptors can’t respond to subsequent photons until Rhodopsin/Photopsin molecules regenerate  
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Lingering visual impressions after a flash of light are an example of what?   Bleaching  
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How do we adapt to brint light?   Bleaching followed by gradual regeneration of Rhodopsin/Photopsin  
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Rhodopsin is found in _______ and Photopsin is found in ________.   Rhodopsin found in Rods, Photopsin found in Cones  
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Functions of Lens   Focuses visual image on Photoreceptors by changing shape  
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Location of Lens   Posterior to Iris; Held in place by Suspensory Ligaments at Ciliary Body  
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The Lens is made up of:   Concentric layers of cells surrounded by a capsule  
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_______ and ________ are absent in Lens fibers   Nuclei and organelles  
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Lens fibers contain _________ (proteins) that provide clarity and focusing power   Crystallins  
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Crystallins   Proteins found in Lens fibers that provide clarity and focusing power  
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The Lens capsule is made up of:   Elastic and collagen fibers that intermesh with Suspensory Ligaments of Ciliary Body  
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Light is refracted at ___ interface(s)   Two: Air/Cornea and Aqueous Humor/Lens  
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When an image is ‘in focus,’ light is refracted to produce:   A single, clear image on the Retina  
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An image is ___________ and ___________ on the Retina   Inverted and Reversed  
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What does an object appear as on the Retina?   Numerous, individual points of light  
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The top of an image lands on the ________ of the Retina   Bottom  
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The bottom of an image lands on the ________ of the Retina   Top  
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The left of an image lands on the ________ of the Retina   Right  
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The right of an image lands on the ________ of the Retina   Left  
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Brain compensates for image __________ and ___________.   Inversion and Reversal  
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20/20   Emmetropia (what a normal person can see at 20 feet)  
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Emmetropia   What a normal person can see at 20 feet  
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20/15   What a normal person can see at 15 feet is seen at 20 feet (better than 20/20)  
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20/200   What a normal person can see at 200 feet is seen at 20 feet (worse than 20//20)  
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Legally Blind means that corrected vision is worse than:   20/200  
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20/200 is ____ diopters   -2.50  
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The Ciliary Muscle contracts to focus on ________ objects   Close  
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When the Ciliary Muscle contracts, the Lens becomes _________.   Rounder  
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What happens to the Ciliary Body when the Ciliary Muscle contracts?   The Ciliary Body moves toward the Lens and reduces tension in Suspensory Ligaments; makes a rounder Lens; ability to focus on close objects  
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The Ciliary Muscle relaxes to focus on ________ objects   Distant  
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When the Ciliary Muscle relaxes, the Lens becomes __________.   Flatter  
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What happens to the Ciliary Body when the Ciliary Muscle relaxes?   The Ciliary Body moves away from the Lens and increases tension in Suspensory Ligaments; makes a flatter Lens; ability to focus on distant objects  
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Myopia   Near-sightedness (Focus in front of Retina)  
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Causes of Myopia (near-sightedness)   Eyeball is too ‘deep’ or Lens is too round  
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Hyperopia/Presbyopia   Far-sightedness (Focus behind Retina)  
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Causes of Hyperopia/Presbyopia   Eyeball is too ‘shallow’ or Lens is too flat  
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The Lens is less elastic and has weaker muscles in people with __________.   Hyperopia/Presbyopia (Far-sightedness)  
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Astigmatism   Misshapen Cornea; Light focused on 2 spots on Retina which causes a blurry image  
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Treatements for Myopia, Hyperopia/Presbyopia, Astigmatism   Corrective lenses (glasses, contacts); Surgery to reshape Cornea  
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Cataracts   Denaturing of crystallin protein in Lens  
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Cataracts cause ___% of blindness worldwide (number 1)   50%  
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Causes of Cataracts   Genetics, radiation, aging  
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Symptoms of Cataracts   Loss of visual, ‘halos,’ impaired color vision  
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In Cataracts, crystallin protein in Lens can “liquefy” over time which can cause the Lens capsule to ________.   Rupture  
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Treatments of Cataracts   High frequency sound waves break up denatured protein, remove proteins but leave lens capsule, implant new lens  
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Visual Pathway (Eyes to Brain):   Photoreceptors → Bipolar Cells → Ganglion Cells → Optic Nerve  
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How many photoreceptors in the Eye?   130 million  
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How many Bipolar Cells in the Eye?   6 million  
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How many Ganglion Cells in the Eye?   1 million  
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There are ______ Rods per every 1 Ganglion Cell (M Cell)   1000  
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Rods go to which Ganglion Cells?   M Cells; M Cell activation signals general stimulation; Less acuity due to convergence (on center neurons respond more strongly than off center neurons)  
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In the Fovea, there is _____ Cone per every 1 Ganglion Cell (P Cell)   1  
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Cones go to which Ganglion Cells?   P Cells; Greater acuity due to lack of convergence (1:1 ratio)  
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Information from only the _________ fields of each eye crosses over at the Optic Chiasm   Peripheral (Lateral)  
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Information from the _________ field does not cross over at the Optic Chiasm   Central  
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Crossing over of information at the Optic Chiasm allows for:   Binocular vision and depth perception  
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Binocular vision and depth perception are possible because:   Information crosses over at the Optic Chiasm  
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Impulse from Optic Tract proceeds to which 3 regions in the Brain?   1. Lateral Geniculate Nuclei in Thalamus (one on each side) 2. Superior Colliculi in Midbrain (sent here from Lateral Geniculate) 3. Suprachiasmatic Nuclei in Hypothalamus (sent here from Lateral Geniculate)  
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Lateral Geniculate Nuclei (in Thalamus) send Optic Radiation on to ________ for interpretation of images   Occipital (visual) Cortex  
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Lateral Geniculate sends visual information to the ___________ in the Midbrain to coordinate Eye movement, papillary reflexes (Melanopsin), etc   Superior Colliculi  
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Lateral Geniculate sends visual information to the ___________ in the Hypothalamus to control circadian rhythm (Melanopsin) and cortisol production   Suprachiasmatic Nuclei  
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