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ANATOMY AND PHYSIOLOGY
THE EYE ANATOMY AND PHYSIOLOGY
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MAJOR PARTS OF THE EYE The OUTSIDE EYELID EYELASHES CONJUNCTIVA IRIS
CORNEA SCLERA EYE MUSCLES The INSIDE AQUEOUS HUMOUR LENS (PUPIL) CHOROID RETINA – RODS / CONES VITREOUS HUMOUR FOVEA OPTIC NERVE
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MUSCLES OF THE EYE
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The Lens Elastic, circular, biconvex, transparent
Held in place by suspensory ligaments It is enclosed in transparent capsule Unique ability – vary its refractive power, by changing its thickness Ciliary muscle contracts, moves forward, making lens thicker as it releases tension.
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HOW THE EYE SEES
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Liquid light Vitreous humour – Posterior segment
Aqueous humour – is in the anterior and posterior chambers – in the Anterior Segment Divided by Iris Secreted by Ciliary glands - continous Passes in front of lens Return via Canal of Schlemm IO pressure mmHg Vitreous humour – Posterior segment 99%water, rest salts and mucoprotien Maintains pressure to support retina Maintains shape of eye Constant through life
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The Retina Innermost layer Made of various light sensitive layers
Rods (contrast or night vision) – Rhodopsin (needs Vit A) Cones (colour vision) Fovea – centre – only cones Optic nerve – convergence of all the nerve fibres
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LACHRYMAL GLANDS AND DUCTS
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FOODS THAT HELP Carrots and other orange foods- beta carotene, vit A
Leafy greens - lutein and zeaxanthin—antioxidants that, studies show, lower the risk of developing macular degeneration and cataracts. Eggs – zinc and antioxidants Berries and citrus fruit – vitamin C Almonds- Vitamin E Fatty Fish - Tuna, salmon, mackerel, anchovies and trout are rich in DHA, a fatty acid found in your retina—low levels of which have been linked to dry eye syndrome
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DISORDERS OF THE EYE TRAUMA – blunt, scratch, pierce
VASCULAR – ischemia & haemorrhage INFLAMMATORY – conjunctivitis, scleritis, iritis, keratitis CATARACT & GLAUCOMA
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SYSTEMIC DISORDERS DIABETES HYPERTENSION THYROID DISORDERS
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