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The Refractive Structures

The Refractive Structures . Light is the material that fuels the visual system. Refractive structures of the eye The light must be bent in exactly the correct pattern for vision to be clear. Refraction = light bending. RHB 340. tears. First refractive structure. conjunctiva.

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The Refractive Structures

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  1. The Refractive Structures • Light is the material that fuels the visual system.

  2. Refractive structures of the eye The light must be bent in exactly the correct pattern for vision to be clear. Refraction = light bending RHB 340

  3. tears • First refractive structure

  4. conjunctiva • Thin “plastic wrap”-like tissue • Covers the inside of the eye lids • Wraps around to cover the entire front surface of the eye

  5. Conjunctiva

  6. Sclera • The white part of the eye • Tough • Fiberous • gives the eye reinforcement

  7. cornea • Front part of the eye • totally clear • Dome-shaped • Is actually an extension of the sclera

  8. cornea

  9. cornea

  10. Anterior chamber

  11. Aqueous humor • Anterior chamber is filled with aqueous humor. • Continually Produced by the ciliary bodies

  12. Since the fluid is continually produced, it must also be removed to keep pressure from building up in the anterior chamber.

  13. Canal of Schlemm

  14. The light enters the eye through the pupil

  15. The size of the pupil is controled by the Iris

  16. The function of the iris is to control the amount of light that is admitted to the eyethe brighter the light, the smaller the iris.

  17. Lens • The lens is located just behind the pupil. • It is: • perfectly clear • Roughly football shaped • flexible

  18. Function of the lens • Focus the image on the back of the eye so a clear image can be seen. • Focuses by getting thinner or thicker • Thinner at near • Thicker at a distance

  19. The ciliary bodies • The ciliary bodies are located on either side of the lens • They have two functions • Anchor the suspensory ligaments which relax and tighten to cause the lense to flatten or get fatter • Produce the aqueous humor

  20. Near and distant vision • Zonules of Zenn tiny muscles that push the lens to make it thicker or relax to allow it to become thinner.

  21. The Lens Distance Near

  22. To review: the anterior structures include • Includes: • Tears • Conjunctiva • Cornea • Anterior Chamber (including the aqueous humor) • Lens

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