SL

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Author:
ijesc
ID:
286134
Filename:
SL
Updated:
2014-10-18 22:09:35
Tags:
OPTM
Folders:
OPTM
Description:
optm SL
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  1. Features of SL
    • 1 variable magn
    • 2 binocular system
    • 3 illumination system
    • 4 joystick/elevation knob
  2. Magnification settings on SL
    • low; 7x-10x; general eye
    • medium; 20-25x; structural layers
    • high; 30-40x; detail
  3. define isocentric
    lamp arm swings on same axis that microscope swings
  4. define parfocal
    microscope is focused on the same plane that the light beam is focused
  5. Hand held SL example
    Hawk eye - portable digital SL
  6. what do we compare result with for normality?
    compare with the other eye
  7. when do we use SL?
    • 1 After H+S and OcHx
    • 2 Best VA (even 6/4 doesnt mean no OcHx problems)
    • 3 Have an indication of OcHx status
  8. haloes around lights suggest?
    ocular oedema
  9. what is associated with dry eye?
    • -some meds e.g. roaccutane
    • -MGD
  10. How do we measure scarring?
    Use graticule
  11. What is blepharitis and how do you record it?
    • -inflammation of the eyelid
    • -draw or photodocumentation
  12. Clinical routine SL (brief)
    • 1 wash hands + disinfect in front of px
    • 2 anterior segment
    • 3 post. segment
    • 4 if something found, use problem specific testing
  13. Clinical routine for SL: Anterior eye
    • 1 Set-up
    • 2 Lids and lashes
    • 3 Ocular surface
    • 4 Anterior segment
    • 5 Fluorescein and lid eversion
    • 6 Dilated
  14. Set-up of SL
    • 1. in front of px, wash hands and disinfect
    • 2. dim room illumination
    • 3. adjust instrument and chair height for both optom and px
    • 4. instruct px
    • 5. adjust chin rest to align canthus mark
    • 6. low mag (6x or 10x)
    • 7. focus oculars + adjust PD
  15. Focussing SL
    • 1 widen PD to max
    • 2 lengthen eyepiece to max
    • 3 slit width to min
    • 4 use focussing rod, tissue box, px nose bridge
    • 5 use naked eye to focus slit
    • 6 swing lamp arm to check focal plane
    • 7 view through one eyepiece only
    • 8 shorten eyepiece till slit is first in focus (overshoot = active acc)
    • 9 repeat for other eye
    • 10 bring oculars in for PD
  16. Evaluating the Lids and Lashes
    • 1 diffuse illumination/broad beam
    • 2 illumination arm 30deg from straight ahead position
    • 3 low mag (6x or 10x)
    • 4 instruct px to close eyes - scan upper lid across lid and lashes
    • 5 in struct px to open eyes - scan lower lid and lashes
    • 6 observe tear meniscus
    • 7 observe lid apposition to globe i.e. puncta not inverted
    • 8 observe for blepharitis or 'demodex' at lash roots
    • 9 observe for any naevi at the lids
  17. what is naevi
    a birthmark (may be a raised red patch) or mole
  18. What is demodex and how to treat
    • - a parasite that lives in the root of lashes
    • - use tweezers to twist at hair follicle (parasite will come out)
    • - treat with reduced conc of tea tree oil
  19. how to observe MG and what to observe
    • - use fingers or cotton bud to pull down lower lid
    • -evert the lid to observe upper lid for MG
    • -infrared camera can indicate gland dropout
    • -look and grade redness and roughness (associated with allergy/sensitivity to CL wear)
  20. anatomy of MG
    • -orifice: the part we see when we flip the lid
    • -acini filled with meibocytes (secretory cells)
    • -meibum is squirted into the central duct
    • -each MG is not always active
  21. how to express MG
    • -use cotton bud
    • -use paddle behind the lid to protect the globe as we are pressing against it
  22. Evaluating the conjunctiva
    • 1 wide parallelepiped (can be done on broad beam)
    • 2 illumination arm 30deg
    • 3 low mag (6-10x)
    • 4 instruct px to open eyes and look up
    • 5 inform px that you will touch the lower lid
    • 6 scan palpebral and bulbar conjunctiva
    • 7 evaluate the openness of the punctum
    • 8 instruct the px to look down
    • 9 inform px that you will touch the upper lid
    • 10 repeat for bulbar and palpebral conj
    • 11 instruct the px to look left then right
  23. Evaluating the cornea
    • 1 narrow parallelepiped (1-3mm wide)
    • 2 illumination arm 30-45deg
    • 3 medium mag 16-20x
    • 4 instruct px to look straight ahead
    • 5 scan across central cornea
    • 6 when you reach the apex of the cornea, swing illumination arm to the other side and continue scanning
    • 7 instruct px to look down
    • 8 elevate upper lid and scan the superior third of cornea
    • 9 instruct the px to look up
    • 9 repeat for lower third of cornea
  24. Layers of the cornea
    • 1 Epithelium
    • 2 Bowmans layer
    • 3 Stroma
    • 4 Descemet's layer
    • 5 Endothelium
  25. signs of infiltrative keratitis
    • 1 bulbar and limball redness
    • 2 diffuse infiltration in periphery to mid-periphery
    • 3 focal infiltrates - clump of WBC; record size and if focal or diffuse
    • 4 CL wearers at a greater risk
  26. more colour fringes on the TF indicate
    a thicker cornea
  27. Typical height and how to measure tear prism
    • -0.3mm or 300 microns
    • -use graticule
  28. evaluate openess of inferior ant. chamber angle
    • -aims to estimate depth of peripheral ant. chamber
    • -by comparing SL optic section of the peripheral cornea to the width of the ant. chamber adjacent to the limbus
    • -assess angle between the back of light falling on cornea and iris at 6 o'clock limbus
    • -assess the rapidity (constancy) of change in chamber depth as you pass beam horizontally across from eye from 6 o'clock to temporal 3 or 9 o'clock limbus
  29. to evaluate openess of ant temporal/nasal chamber angle - van herick test
    • 1 fixation straight ahead
    • 2 lamp 30deg - beam is ~ perpendicular to cornea
    • 3 microscope 30deg - wide view angle to see layering ratio confidently
    • 4 mag 16x-20x
    • 5 place optic section as close to the temporal limbus as possible
    • 6 how many 'corneas' can fit into the aqueous
  30. recording van herick
    • -for nasal/temp - record in ratio: ant ch/cornea
    • -for inf angle: record in degrees
  31. van herick criterion
    • -chamber must be EQUAL or GREATER than 0.3 corneal thickness
    • -may proceed to instil mydriatic without checking angle with goniolens or having miotic in hand
  32. what is miosis
    contraction of pupil
  33. what is miotic
    an agent that causes miosis
  34. why evaluate ant chamber
    -to detect eyes at risk of ACG
  35. what is ACG
    angle closure glaucoma
  36. What is the gold standard for assessing ant angle?
    gonioscopy gives you 360deg of the angle
  37. Non-invasive techniques for assessing the ant angle are
    • 1 ultrasonic biomicroscopy
    • 2 Scheimpflug imaging
    • 3 OCT
  38. what is OCT
    optical coherence tomography
  39. evaluating the iris with SL
    • 1 slit width to wide parallelepiped
    • 2 illumination arm 30-45deg
    • 3 maf 16x-20x
    • 4 scan across surface for irregularities
    • 5 if irregular, note size, how defined, elevated, evenly pigmented, b.v., any naevi
    • 6 note pupillary reflex and pupil shape i.e. pupil should of undilated eye should constrict when light reaches the pupillary margin
  40. evaluating ant chamber with SL
    • 1 to check for presence of cells and flare in the aqueous e.g. if you suspect px has ant uveitis
    • 2 reduce all room illumination
    • 3 illumination arm 30deg
    • 4 mag 25-40x
    • 5 conical beam - 'torch' like appearance
    • 6 direct beam into pupil - move SL back and forth to focus between the cornea and the ant surface of the lens
  41. SUN is used to grade?
    the ant chamber for cells and flare
  42. what is flare
    'foggy' appearance given by protein that has leaked from inflamed blood vessels
  43. uveitis is?
    inflammation of the uvea (pigmented layer of the eye: iris, CB, choroid)
  44. evaluating the lens with SL
    • 1 illumination arm to 20deg
    • 2 mag 16-20x
    • 3 narrow parallelepiped
    • 4 move SL closer to px until light is directed through the pupil and sharply focused on the ant lens surface
    • 5 continue to move closer to px to look at deeper layers of the lens
    • 6 focus on the post. lens surface
  45. The LOC scale grades?
    LOC - Lens opacities classification
  46. lid eversion
    • 1 done for all CL wearers, px with red eyes, history of FB or itchiness
    • 2 px positioned behind SL
    • 3 px to look down
    • 4 grasp px upper lid margin with thumb + index finger
    • 5 gently pull lid down and out
    • 6 with other hand, place cotton bud at post. margin of the tarsal plate in centre of lid
    • 7 gently press down bud while pulling lid up and over it
    • 8 remove bud and keep holdinig lid up at the centre
    • 9 scan everted lid with SL
    • 10 to flip back over, ask px to look up and keep finger on lid to support it
  47. Fluorescein stains:
    • 1 cornea
    • 2 palpebral conj
    • 3 bulbar conj
    • 4 Seidel's sign (leaking aqueous with deep corneal wound)
  48. lissamine green stains:
    • 1 lid wiper
    • 2 bulbar conj
  49. process of corneal integrity check
    • 1 assess in white light (draw/record any obsv)
    • 2 instil fluorescein
    • 3 SL to cobalt blue filter and broad beam
    • 4 grade corneal to CCLRU according to extent, depth and type
    • 5 to establish depth, white light, p'ped or OS, grade to CCLRU
  50. when do we do corneal integrity check?
    • 1 part of routine assessment
    • 2 prior and after every invasive technique - tono and gonio
    • 3 record corneal appearance pre and post invasive technique
    • 4 grade 3 staining or above will be referred to red eye clinic
  51. SICS stands for
    solution-induced corneal staining
  52. TBUT
    • 1 instil a small vol of fluorescein
    • 2 ask px to blink twice, then 'dont blink'
    • 3 count the seconds to when we observe the even spread of green tears starts to break
    • 4 typical TBUT= 10secs
  53. lid margin staining is...
    associated with dryness symptoms in CL wearers and non wearers
  54. other clinical routine tests
    • 1 IOP goldmann tonon
    • 2 gonio
    • 3 fundoscopy
  55. illumination techniques in SL
    • 1 diffuse
    • 2 direct
    • 3 indirect
    • 4 retro-illumination
    • 5 specular reflection
    • 6 sclerotic scatter
    • 7 tangential
  56. light beam focal types
    • 1 afocal (unfocused, diffuse)
    • 2 focal
  57. light beam shapes + draw
    • 1 OS - 0.1mm (super narrow)
    • 2 p'ped - 0.5-2mm (narrowish)
    • 3 broad - >2mm (broad)
    • 4 conical - short height and narrow
  58. incident angle types from the light beam
    • 1 direct - from in front
    • 2 indirect - not in front or behind
    • 3 retro - from behinf
    • 4 direct retro - bright background
    • 5 indirect retro - dark background
    • 6 rarely use 0deg incident lighting = px discomfort when connects with fovea
  59. set up for diffuse illumination
    • 1 45 deg b/t light + microscope
    • 2 slit fully open
    • 3 diffusing filter on
    • 4 variable mag (low to high)
    • 5 fine details lost
  60. diffuse illumination gives us what view?
    • an overall view of
    • 1 lids and lashes
    • 2 conj
    • 3 cornea
    • 4 sclera
    • 5 iris
    • 6 pupil
  61. define direct illumination + draw
    • -observation and illumination systems focused on the same point
    • -point of regard lit 'front-on'
  62. properties of direct illumination
    • 1 vary angle of illuminaton
    • 2 low to high mag
    • 3 vary width and height of light source
  63. direct illumination beam types
    • 1 OS - narrow focused light
    • 2 p'ped - wider focused light
    • 3 conical beam - small, circular light
  64. properties of the OS
    • 1 thinnest beam - at its focal plane
    • 2 indicates depth
    • 3 'geological' cross section - view individual layers, any thickening, thinning, make depth judgements
    • 4 can localize - nerve fibres, b.v., infiltrates, cataracts, ant chamber angle
    • 5 edge of lit up tissue appears sharp if it coincides with the beam's focal plane
    • 6 direct
  65. OS and the crystalline lens
    widen OS to see Y sutures
  66. properties of the p'ped
    • 1 narrowish beam 0.5-2mm
    • 2 reveals 3-D box of tissue
    • 3 reveals breadth of anomaly(abnormality) but decreases contrast
    • 4 direct
  67. properties of conical beam + draw
    • 1 short narrow beam 0.5x0.5mm
    • 2 totally dark room
    • 3 swing lamp to all angles to scan ant chamber
    • 4 in inflammatory conditions can see individual WBC and fibrin floating (cells and flare)
    • 5 Direct technique
  68. indirect illumination
    • -light is bounced beyond point of original direct impact to illuminate obj of regard from the side or from behind
    • -use the offset knob or look off centre from FOV
  69. how to use offset knob
    • 1 focus on pt of regard with 'direct' light
    • 2 offset beam¬†
    • 3 incident lighting no longer appears at exact centre of FOV
  70. define indirect illumination + draw
    • observation and illumination systems are not focused on the same point
  71. properties of indirect illumination
    • 1 vary angle of illumination
    • 2 slit beam is offset
    • 3 vary beam width
    • 4 low to high mag
  72. indirect illumination is valuable for observing...
    • 1 epithelial vesicles
    • 2 epithelial erosions
    • 3 iris pathology
  73. what is proximal viewing?
    • 1 indirect illumination
    • 2 looking adjacent to where the light beam strikes
  74. define retro illumination + draw
    • object of regard is illuminated only by reflected light
  75. properties of retro illumination
    • 1 vary angle of illumination
    • 2 moderately wide beam
    • 3 slit beam is offset
    • 4 medium to high magnification
    • 5 reflected light from iris or fundus
  76. types of retro-illumination + its alignment
    • 1 direct - direct and full view
    • 2 indirect - adjacent
    • 3 marginal - margin or edge
  77. properties of direct retro
    • 1 bright background
    • 2 opaque objects seen silhouetted
    • 3 translucent objects 'melt' into the background
  78. properties of indirect retro
    • 1 dark background
    • 2 translucent object refract light
    • 3 opaque objects may have a diffraction ring of light around it
  79. properties of marginal retro
    • aka oscillatory
    • 1 at boundary of bright/dark zones
    • 2 changes to appearance more readily detected than steady-state
  80. retro-illumination is valuable for observing:
    • 1 vascularization
    • 2 epithelial oedema
    • 3 microcysts (small round vesicle containing fluid and cellular debris on the surface of the cornea)
    • 4 vacuoles
    • 5 dystrophies (disorder where the tissue wastes away)
    • 6 crystalline lens opacities
    • 7 CL deposits
  81. info about retro off the fundus
    • 1 use a very small angle between the lamp + microscope
    • 2 the darker the fundus the poorer the chance of seeing anomalies (irregularities)
  82. when do we look at the anterior eye
    • 1 ALWAYS after dilation - dark backdrop of pupil may provide more detail
    • 2 retro off fundus may also provide more detail
    • 3 check the cornea, lens, iris, ant. vitreous for PVD (Schaffer's sign -¬†retinal pigment particles floating in the anterior vitreous chamber behind the lens; increases suspicion for a tear or detachment)
  83. define specular reflection + draw
    • angle of incidence equals angle of reflection
  84. specular reflection is valuable for observing
    • 1 endo cell layer
    • 2 TF debris
    • 3 TF lipid layer thickness
    • 4 highlights elevations/depressions
  85. how to evaluate corneal endo
    • 1 specular reflection
    • 2 medium width p'ped
    • 3 begin on low-med mag
    • 4 30deg illumination arm
    • 5 focus on cornea
    • 6 change arm angle or move joystick until slit beam intersects reflection of the light filament: i=r
    • 7 should only see reflection of EPI from ONE ocular only
    • 8 increase mag to highest
    • 9 focus sharply on endo and observe its mosaic appearance
  86. sclerotic scatter is for observing
    • 1 localised epithelial oedema (CCC)
    • 2 corneal scars
    • 3 FB in the cornea
    • i.e. mildly disturbed corneal transparency
  87. method of sclerotic scatter
    • 1 use p'ped
    • 2 45deg illumination arm
    • 3 focus beam on temporal limbus
    • 4 view cornea indirectly
    • 5 OR focus on cornea then offset so light beam is on limbus while focused on cornea
  88. sclerotic scatter is used to
    view the central cornea (indirect) lighting against a dark pupil
  89. tangential illumination + draw
  90. tangential illumination valuable for observing
    • 1 iris freckles
    • 2 tumours
    • 3 general integrity of cornea and iris
    • 4 highlights elevations and depressions
  91. properties of tangential
    • 1 narrowish beam
    • 2 tangential to tissue in qn
    • 3 direct

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