Ultrasound and glaucoma

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  1. Ultrasound
    Cyclic sound pressure with a frequency greater than the upper limit of human hearing
  2. A scan mode
    Amplitude of echo spike over time
  3. B scan mode
    Ultrasound signal used to produce various points whose brightness depends on amplitude instead of the spiking vertical movements in A mode
  4. Reasons for ultrasound
    • Axial length (primary and secondary iol)
    • opaque media (hyphema, cataract, vitreous debris)
    • trauma (posterior rupture of globe, no scan is sidel positive)
    • pediatric cases (fundus view, leukocoria)
  5. Corneal thickness
  6. Lens thickness
    4.979 mm
  7. Cornea to lens
    2.794 mm
  8. Ultrasound frequency
    Between 2 and 50MHz
  9. A scan
    Amplitude mode
  10. B scan
    Brightness mode
  11. W pattern
    Orbital fat
  12. V
    Optic nerve
  13. PVD
    Aging causes liquefaction of vitreous gel - low reflective
  14. Asteroid hyalosis
    Calcium soaps - highly reflective dot like interfaces - usually with anechoic band
  15. Retina pathology
    Less mobile than vitreous membrane
  16. Uveal tract / choroid
    Contour smooth to globe, annular appearance within the anterior aspect of the globe is effusion with diffuse thickening posterior pole
  17. Melanoma
    Most common primary lesion of globe, single lesion, RD
  18. Ocular coherence topography
    Color or grey scale high resolution images of layers of retina,
  19. Oct
    Volume measurements of the macular region
  20. Glaucoma
    A group of disorders that result in damage to the optic nerve and vision loss.
  21. Glaucoma risk factors
    African Americans, age, elevated iop, family history
  22. Cause of iop rise
    Rate of aqueous humor production, resistance to aqueous outflow, episcleral venous pressure
  23. Primary resistance
  24. Primary angle closure glaucoma
    Shallow ant. Chamber, pupillary block, increased pressure in post chamber, Iris bomb'e, damage to lens epithelim, minute ant sub caps opacification, corneal edema
  25. Secondary glaucoma
    Trauma, inflammation, tumor or malformation, chronic retinal ischemia and increased VEGF, necrotic tumor, iridocorneal endothelial syndrome, episode down growth, cilliary body tumor
  26. Imbert-Fink principle
    P=F/A. Pressure in sphere equals the force necessary to flatten its surface divided by the area flattened
  27. Common vf defects
    Arcuate, superior, paracentral, seidel scotoma, complete arcuate, sup/inf arcuate, superior nasal step, vertical step
  28. Sits 24-2
    Swedish interactive threshold algorithm
  29. False negatives and false positives
  30. Fixation losses
  31. Total deviation
    Difference between measured threshold for each retinal point and age corrected normal
  32. Pattern deviation
    Total deviation adjusted to equal an average of the 17 worse test points, eliminating background noise like cataract
  33. Pattern standard deviation
    Measures localized defects and how they deviate from age corrected normals
  34. Gdx - retard test
    Scanning laser polarimetry measures peripapillary RNFL, cell axons in retina cause polarization of light
  35. TSNIT graph
    Depicts different thicknesses of peripapillary RNFL
  36. OCT peripapillary scan
    3.4 mm measuring RNFL
  37. OCT stratus
    Time domain 5 micron
  38. OCT Spectralis
    Fourier. Domain 2 microns
  39. Heidelberg retina tomography
    Confocal scanning laser, principle of spot illumination and spot detection.
  40. Types of drops
    Miotics, beta-blockers, alpha-agonists, carbonic anhydrase inhibitors, prostaglandin analogs
  41. Glaucoma lasers
    Argon laser trabeculoplasty, selective laser trabeculoplasty
  42. When should laser be considered
    Pigment dispersion, pseudoexfoliation, non compliant, allergic, what iop drop would you expect? How long does it last?
  43. Glaucoma surgery
    Trab, trab with express mini shunt, Ahmed valve, baerveldt valve, trabectome, canaloplasty, edocyclophotocoagulation, trans-scleral cyclophotocoagulation
  44. ECP
  45. TSCPC
    Trans-scleral cyclophotocoagulation
Card Set:
Ultrasound and glaucoma
2011-05-05 00:14:42
Ultrasound glaucoma

Basics of ophthalmic ultrasound and glaucoma
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