Card Set Information

2013-11-02 22:13:17

Show Answers:

  1. The eye is made up of three layers
    • -the outer layer called the fibrous tunic
    • -the middle layer responsible for nourishment, called the vascular tunic
    • -the inner layer of photo-receptors and neurons called the nervous tunic
  2. fibrous tunic
    which consists of the sclera and the cornea
  3. vascular tunic
    which consists of the iris, the choroid, and the ciliary body
  4. nervous tunic
    consists of the retina
  5. The eye also contains three fluid-filled chambers
    • anterior chamber
    • posterior chamber
    • aqueous humor
  6. anterior chamber
    The volume between the cornea and the iris
  7. posterior chamber
    the volume between the iris and the lens
  8. aqueous humor
    both chambers contain a watery fluid
  9. Ciliary body
    • -Aqueous humor is watery fluid produced by the
    • -It maintains pressure
    • -Provides nutrients to the lens and cornea
  10. Canal of Schlemm
    Aqueous humor is continually drained from the eye through the
  11. vitreous chamber
    The greatest volume, forming about four-fifths of the eye, is found between the retina and the lens.
  12. Vitreous humor
    • -The vitreous chamber is filled with a thicker gel-like substance
    • -maintains the shape of the eye
  13. cornea
    Light enters the eye through the transparent, dome shaped
  14. The cornea consists of five distinct layers
    • endothelium
    • Descemet's Membrane
    • stroma
    • Bowman's Membrane
    • epithelium
  15. Epithelium
    • -The outermost layer
    • -Has the ability to quickly regenerate (7days turn over time, corneal abration 24-48 hours)
    • -5-6 cells thick
  16. Bowman's Membrane
    • -Second layer
    • -If injured does not regenerate
    • -Provides a tough, difficult to penetrate barrier
  17. Stroma
    • -middle layer
    • -makes up 90% of the thickness of the cornea
    • -lattice type arrangements
  18. Descemet's Membrane
    • -Thickens over life time double by age 40
    • -Provides a tough, difficult to penetrate barrier
  19. Endothelium
    • innermost layer
    • removes water from cornea, helping to keep the cornea clear
    • - Single layer of hexagon shaped cells
    • -Do not divide and repicate
  20. Pupil
    • -Light passes through
    • -The dilator muscle opens the pupil allowing more light into the eye and the sphincter muscle closes the pupil, restricting light into the eye.
  21. Iris
    • The colored part of the eye. The iris has two muscles: the dilator muscle and the sphincter muscle.
    • The iris has the ability to change the pupil size from 2 millimeters to 8 millimeters.
  22. crystalline lens
    Just behind the pupil. The purpose of the lens is to focus light on the retina.
  23. Accommodation
    The process of focusing on objects based on their distance.
  24. Retina
    • Light reaches its final destination
    • consists of photo-receptor cells called rods and cones.
  25. Rods
    are highly sensitive to light and are more numerous than cones. There are approximately 120 million rods contained within the retina, mostly at the periphery.Not adept at color distinction, rods are suited to night vision and peripheral vision.
  26. Cones
    on the other hand, have the primary function of detail and color detection. There are only about 6 million cones contained with in the retina.
  27. There are three types of cones
    Each type receives only a narrow band of light corresponding largely to a single color: red, green, or blue.
  28. optic nerve
    The signals received by the cones are sent via the optic nerve to the brain where they are interpreted as color.
  29. Emmetropia
    normal eye
  30. Myopia
    • also known as near-sightedness
    • occurs if the eye is longer than normal or the curve of the cornea is too steep, causing light rays focus in front of the retina.
  31. Hyperopia
    • also known as far-sightedness
    • occurs if the eye is too short or the curve of the cornea is too flat, causing light rays to focus behind the retina.
  32. Astigmatism
    Astigmatism occurs when the cornea has an oblong, football-like shape in one or more directions (or axes) causing light rays to focus on more than one point on the retina.
  33. Presbyopia
    • The crystalline lens begins to lose elasticity.
    • With the loss of elasticity, the eye loses the ability to accommodate or focus at near.
    • This typically becomes noticeable around 40 years of age.
  34. Anisometropia
    a condition in which the two eyes have unequal refractive power.
  35. six extraocular muscles attached to the eye
    • Lateral rectus
    • Medial rectus
    • Superior rectus
    • Inferior rectus
    • Superior oblique
    • Inferior oblique
  36. Lateral rectus
    moves the eye outward, away from the nose
  37. Medial rectus
    moves the eye inward, toward the nose
  38. Superior rectus
    moves the eye upward and slightly outward
  39. Inferior rectus
    moves the eye downward and slightly inward
  40. Superior oblique
    moves the eye outward and downward
  41. Inferior oblique
    moves the eye outward and upward
  42. Diplopia
    double vision
  43. Phoria
    When the eye has a tendency to turn from its normal position
  44. Tropia
    the eye has a definite or obvious turning from its normal position
  45. exo
    meaning outward
  46. eso
    meaning inward
  47. exotropia
    outward or in a temporal direction
  48. esotropia
    inward or in a nasal direction
  49. hyperphoria
    hyper meaning upward
  50. hypophoria
    hypo meaning downward
  51. hyper
    meaning upward
  52. hypo
    meaning downward