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THE EYE

THE EYE. CHAPTER 10. QOD #1: Pre-Test. 1.) What are the 5 senses? 2.) T/F Of all the sensory receptors in the body, 70% are in the eyes. 3.) T/F Your eyebrows have no function. 4.) T/F If you are colorblind, you do not see any color.

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THE EYE

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  1. THE EYE CHAPTER 10

  2. QOD #1: Pre-Test 1.) What are the 5 senses? 2.) T/F Of all the sensory receptors in the body, 70% are in the eyes. 3.) T/F Your eyebrows have no function. 4.) T/F If you are colorblind, you do not see any color. 5.) T/F If you are farsighted, you cannot see objects that are in close proximity. 6.) _________ is caused by an increase in pressure in the eye.

  3. The eye • 70% of sensory receptors in the body are found here. • Housed in the orbit of skull and surrounded by fat, blood vessels, nerves, and connective tissues. • 2.5cm in diameter • 3 layers (tunics/coats) • Outer layer (fibrous) • Protective, refracts light • Includes cornea and sclera • Middle layer (vascular) • Contains pigments to keep eye dark inside • Includes choroid coat, ciliary body, lens, iris, pupil, aqueous humor. • Inner layer (nervous/sensory) • Visual receptors • Contains retina, fovea, optic disc, vitreous humor

  4. Pathway of Light Cornea Aqueous humor Pupil Lens Vitreous humor Retina

  5. EYE PHYSIOLOGY • Refraction: occurs when light waves are bent • Normal • Image is upside down • Visual cortex of brain interprets it in its proper position

  6. Physiology cont… • Accomodation: • Occurs when the lens adjusts its shape to focus on objects. • Ciliary muscles and suspensory ligaments aid in doing this • When the ligaments pull outward the lens flattens and focuses on distant objects • When ligaments are relaxed the lens is more convex (thickens) focusing on closer objects

  7. VISUAL ACUITY • Ophthalmoscope: instrument that illuminates the interior of eyeball allowing the inside to be seen. • Snellen eye chart: • measure acuity • 20/20 normal vision • Higher the number the poorer the vision

  8. Eye problems • Myopia: near sighted • Hyperopia: far sighted • Emmetropia: normal vision • Astigmatism: cornea/lens developed an irregular shape • Strabismus: cross-eyed • Diplopia: double vision (can be caused by one eye deviating from line of vision). • Blindness: most common cause is loss of transparency of the cornea • Cornea transplant (high success rate b/c no blood vessels)

  9. Eye problems cont.. • Cataract: lens becomes cloudy (laser surgery to fix) • Glaucoma: increase in intraocular pressure, caused by an increase in aqueous humor • Tonometer: instrument measuring pressure • Night blindness: poor vision in dim light resulting from a vitamin A deficiency.

  10. Normal Vision ColorBlind  Color Blindness: Genetic disorder carried on the X chromosome. Most common is red/green color blindness.

  11.  Normal Vision Color Blind 

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