Ophthalmic Lecture

  1. What are the 4 fluid compartments of the eye?
    Tear, anterior, posterior and vitreous chamber.
  2. What is the outermost part of the eye?
    The tear chamber.
  3. List the 2 functions of the eyelid.
    Protect the eye from foreign object and perspiration.
  4. The name of the tissue that lines the inside of the eyelid.
    The conjunctiva.
  5. Name of the opening that the tears drain through.
    Puncta opening.
  6. The eyelids' 3 types of closing are:
    Blinking, voluntary winking and blepharospasm (involuntary rapid closing of the eyelids).
  7. What is blepharospasm.
    Involuntary rapid closing of the eyelids.
  8. What is another name for involuntary rapid closing of the eyelids.
  9. Name the tissue that makes the eyelid continuous with the eyeball.
    The conjunctiva.
  10. What does the conjuctival membrane do?
    It makes the eyelid continuous with the eyeball.
  11. What does the conjuctivaMembrane consist of?
    Epithelium and an underline Substantia propria.
  12. What happens to the conjunctiva During inflammation?
    The blood vessels can be seen as they dilate.
  13. Part of the eye aka "whites of the Eye."
  14. What are the phyiscal characteristics Of the sclera?
    It's very rigid and vascular. It also Has dense fibrous tissue.
  15. T/F. Sclera contributes to eye stability.
  16. What is the cornear important for?
  17. How does the cornea work?
    The curved transparent window of the eye allows light to enter, become focused to give rise to an image in the retina.
  18. The 3 layers the cornea consists of:
    Epithelium, substantia propia and endothelium.
  19. T/F. The cornea contains blood vessels.
  20. What happens to the cornea during inflammation and what can be the consequence of this?
    Vascular tissue forms on the cornea and can lead to impairment of vision.
  21. How does the cornea receive oxygen?
    Through passive diffusion from the nearby tears chamber and blood vessels.
  22. How many ul of tears are in the eye annd what is the rate @ which they are cont. replaced?
    7ul; 1ul/min.
  23. The functions of tears are to?
    To remove foreign matter, moisturize cornea, destroy bacteria and supply oxygen to cornea.
  24. List the ophthalmic dosage forms.
    GODSS: Gels, ointments, drug impregnated inserts, Suspensions and Solutions.
  25. Part of the eye tear fluid is contained.
    Cul de sac.
  26. What is the normal volume of tear fluid?
    7-8 ul.
  27. A nonblinking eye can hold how much fluid?
  28. A blinking eye can hold how much?
  29. The approx. % of drug that is absorbed intraoccularly.
  30. Dosage forms that increase contact time, thus increase bioavailability.
    Gel and cream.
  31. Name the 2 chambers where most of the drug goes to.
    Tear and anterior.
  32. What are the drug barriers/things that reduce Drug absorption @ the tear chamber.
    Tear drainage, dilution, metabolism, protein binding, Loss from blinking (non-productive loss).
  33. What are the barriers/things that reduce drug abs. @ Cornea?
    Lipophillic/hydrophillic barrier and metabolism.
  34. What are the barriers/things that reduce drug abs. @ Anterior chamber?
    Metabolism, protein binding, turnover of aq. Humor.
  35. What is one issue of systemic administration of an ophthalmic?
    Dilution can occur in a large volume of distribution.
  36. You can lose up to __% of drugs administered topically to eye, and have as little as __% or less absorption of drug.
    90 and 1.
  37. What dilutes the drug?
    Tears from tear chamber.
  38. Approx. how much dilution can we expect?
  39. Why is there solution drainage ?
    So that the instilled soln can = normal volume of tears.
  40. Explain the relationship b/w volume of soln instilled and rate of draining.
    As volume increases, draining increases.
  41. How can draining be decreased?
    Increasing viscosity.
  42. Does drug loss increase or decrease if pt. closes eye forcefully?
  43. Most commercial droppers deliver how much soln?
  44. Besides viscosity, what is another way to reduce draining?
    Use smaller drops.
  45. How does tear turnover rate affect drug loss? What is the rate of tear t/o?
    The rate is 15%/min. Tear t/o reduces the time that the eye has to absorb the drug.
  46. T/F. only protein bound drugs can be removed by drainage in tear and aq. Humor
    False. Free drugs can be removed too.
  47. How can you minimize protein binding?
    Prewash the eye to remove protein that binds.
  48. Enzymes that metabolize opth drugs are found where?
    Tears, cornea and aq. Humor.
  49. T/F. Extensive metabolism occurs in the tear chamber.
  50. Extension metabolism occurs where in the eye?
    Cornea and aq. Humor (contact time is longer).
  51. What is the main barrier to absorption to the eye?
  52. List thhe 3 parts of the cornea.
    Epithelium, substantia propia, endothelium.
  53. What factors affect the absorption of lipoliphillic drugs across corneal epithelium? How do each effect it?
    pH, tonicity, and state of ionization. pH below 3 or above 11 can destroy epithelium= Increased drug uptake. Tonicity can stimulate tears= more dilution and drainage. State of ionization= nonionized =Better corneal penetration.
  54. Most drugs cross the cornea by what mode of diffusion?
  55. Sodium and small molecules cross the cornea by what kind of diffusion?
  56. What is the optimum partition coefficient for corneal penetration?
  57. What can you do if you cannot include preservations in an ophthalmic soln (due to allergies)?
    Put in single use container.
  58. How can you modify an ophthalmic to increase effectiveness of preservative?
    Increases it's viscosity to increase conact time w/ microorg. Use a thickening agent such as: Polyvinyl EtoH, methylcellulose and hydroxypropylcellulose/cellulose derivatives.
  59. T/F. Cellulose thickening solns cannot be filtered; they must be autoclaved.
  60. T/F. Solubility of cellulose decreases in hot water.
  61. The preservations most effective against strains of P.aeruginosa?
    Mix of Benzalkonium Cl (1:10000) and Polymyxin B Sulfate (1000USP units/mll) or benzalkonium cl (1:10000) and Disodium ethylenediaminetetraacetate (1:1000).
  62. Which method of filtration is safe to use for ophthalmics? Why? Drawback of these methods?
    Filtration. Stability unknown. Cannot remove viruses.
  63. Solns which heat resistant drugs can be autoclaved @ what temp and for how long?
    121oC for 15 min.
  64. Why is it impt to adjust pH of ophthalmic solns?
    comfort, stability and aq. Solubility of drug, bioavailability of drug, for preservative to work better.
  65. What is the pH of tears?
  66. Preferred pH of ophthalmic?
    7.4 (not always possible) why?
  67. When is a soln isotonic with tears?
    Same osmotic pressure.
  68. Osmotic pressure is the result of what dissolved in the soln?
  69. The range of osmotic pressures the eye can tolerate?
    0.5-1.6% of the pressure of tears.
  70. What is more impt: tonicity of eyewash or eye drops? Why?
    Eyewash b/c the volume used is greater than eyedrops. The tonicity of the eyedrops can be adjusted by the tears.
  71. Can you adjust the tonicity for both hypotonic and hypertonic drugs?
    No, only hypotonic.
  72. Define viscosity.
    An expression for the resistance of a fluid to flow
  73. What is the reciprocal of viscosity?
  74. Unit of viscosity?
  75. Define Poise.
    The amount of shearing force to produce a velocity of 1cm/sec b/w two parallel planes of liquid that are 1cm apart.
  76. What external factor affects viscosity?
  77. Range of viscosity for ophthalmic solns?
  78. Name an instrument used to measure viscosity. How does it measure?
    Capillary viscometer. Measures time it takes for a fluid to flow from one end of the cap. Tube to other relative to reference fluid.
  79. What ophthalmic dosage form doesn’t get washed out by tear fluid as easily as soln?
  80. Name two sterilization methods of opth. Oint?
    Dry heat + radiation.
  81. In addition to sterility, what else must be monitored in an oph. Oint?
    # and size of metal particles present from metal tube packaging.
  82. Why make opht. Suspensions?
    When drug has low solubility in aq. Media.
  83. Particle size of opht. Suspensions?
  84. What components are in an opth suspension?
    Surface active agent, thickening agent, antimicrobial, NaCl for tonicity.
  85. What is the greatest danger when instilling ophthalmic solns?
    Contamination from the dropper!
  86. Steps pt. should take when instilling ophthalmic soln?
    Wash hands!!--> sit w/ head tilted looking up--> pull lower lid down, and instill into outer corner of lower lid. Avoid dropper contact w/ eye.
Card Set
Ophthalmic Lecture
5302. 1/2/2012