Upload
nnmmbbvvccxxzz
View
286
Download
2
Embed Size (px)
Citation preview
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 1/22
7/11/20
Principles Pt 1
SLIT LAMP BIOMICROSCOPY
The EBAA Technician Education Seminar2011
George OD Rosenwasser, MD, CEBTGift of Life Donor Program
Hershey, PA
Slit Lamp Biomicroscopy I
• Overview of the use of the slitlamp in eye banking
• Basic slit lamp anatomy
• Slit lamp designs
• Slit lamp operation
• Eye bank tissue examination
• Advanced techniques• Specular reflection
• Special lighting techniques
The Slit Lamp Exam
• Eye anatomy
• Slit lamp basic• operation
• illumination techniques
• What to look for
amp xamGoal
• Slit Lamp Goal: Does the cadaveric cornea meet eye bankcriteria?
• Determine if the cornea suitable for transplantation
• Assure that corneal donor is anatomically and functionallysuitable, optically clear, and infection-free
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 2/22
7/11/20
Why do the slit lamp exam?
• To see if there are reasons to exclude the cornea from beingtransplantable
• To determine if the cornea can be used in some applications butnot others
• DSAEK (rim size important)
• PKP (scars, previous refractive surgery may exclude)
• DALK (as in PKP but bad endothelium not an issue)
• Patch Graft (almost any cornea can be ETOH or Glycerinepreserved)
• Slit lamp exams are done to globes orcorneoscleral rims after retrieval in theeye bank
• The specimen needs to be warmed toroom temperature. This preventscondensation on chamber. Do specularexam immediately after.
What, Where and When?
CSVC with IR
thermometer CSVC with Condensation
Whole Globes
• With jar cover off and bottom tilteddownward
Corneoscleral Rims inGlass Scintillation Vials• Cap on, using a 45 degree mirror to
view through the bottom
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 3/22
7/11/20
Corneoscleral Rims in CSVC’s (Corneal Storage and Viewing Chambers)
• Can view through top optical flat orbottom
So What Do We Look For
Now That We’re There? • Systematically examine the specimen
• Anatomical order• Size of rim
• Clarity/opacity overall
• Conjunctiva
• Epithelium
• Stroma
• Descemet’s
• Endothelium
Atlas of Eye Banking andCorneal Evaluation
http://telemedicine.orbis.org/bins/content_page.asp?cid=1-1581
Anatomy Review
Anterior and Posterior Chamber
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 4/22
7/11/20
Epithelium
Bowman’s
Stroma
Descemet’s
Endothelium
Corneal Layers: HumanSlit Lamp
Capabilities
• Provides a good, magnified,medium-tech anatomical view
of all corneal layers
• Does not give a functionalview, so metabolic orinfectious status is unknown
Slit Lamp Design
• Horizontal• Zeiss, Topcon, Marco
• Vertical• Haag Streit, Topcon, Marco
• Slit BeamVariability• Height, Width, Focus
• Callibration
• Filters
• Backlighting
Slit Lamp Design•Horizontal• Zeiss, Topcon, Marco
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 5/22
7/11/20
The Slit Lamp
• Biomicroscope to
examine a living eye
• Parts:• Binocular Microscope
• Produces magnified view of cornea,
with stereopsis
• Converging or Parallel optics
• “Slit” light beam • Intense light, gives cross sectional
illumination
• Fine, delicate optical instrument
Light Source
Microscope
Slit Lamp Styles
• Light source and microscopepivot around same point
• Keeps focus (parfocal)• Light source can be decentered
and used for special illumination• Controls to adjust for slit height
and width• Horizontal or Vertical Slit Beam
Projectors
Slit Lamp Anatomy
Slit Projector
Zeiss and Clones
• Horizontal slit projection system
• Parallel optics
• Four position Galilean telescope tochange magnifications
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 6/22
7/11/20
Haag Streit and Clones
• Vertical slit projector system withfront surface mirror
• Two or four magnifications
• Converging optics• Older and knock-off models may require
accomodation
Slit Lamp Anatomy
Slit Projector
Holding the Cornea
• Varies by container style• CSVC most common
• Scintillation vial (glass bottle), phenolic cap
• Horizontal• Three finger lab clamp
• Need 90 degree adapter to connect to slit lamp
• Suitable for CSVC
• Vertical• Requires a mirror at 45 degrees
• several commercial and home brew methods
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 7/22
7/11/20
Glass Scintillation Vial
View the floating/sinkingcornea through the mirror
May need to gently swirl the
cornea to see both sides
Saves the expense of the CSVC
CSVC: Corneal Storage andViewing Chamber
• Gently clamp the fully closed CSVC inthe fingers
• View through optical flats (top isbetter)
Slit Lamp Basics
• Slit Lamp Mechanics• Adjust Oculars
• Par-focality
• Slit adjustment
• Lighting Methods
• Slit Lamp Pathology Just like musicians need to tune
their instruments, we need to
prepare our main instrument
Adjust the Oculars
• Find out if you are slightly near or farsighted and dial this into your oculars• Minus if near sighted, Plus if far sighted
• If there is a reticle, focus based on it
Also adjust the “PD” (pupillary distance)to get full binocular view
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 8/22
7/11/20
Parallel vs Converging Optics
• Parallel means eyesare focused at infinity
• Converging means astate of near focusing at
all times• important if over forty or
hyperopic (far-sighted)
Converging vs Parallel
Slit Beam Adjustment• Place calibration rod, or a card as a target
• Position slit projector between the oculars• narrow the slit,
• should be in the center
• focus it on the card or rod
• rod is always at the focal plane
• If not, check if you can adjust it or call arepair technician
• Turn the adjustments on the eye pieces oneat time to focus, while the other eye is closed
Calibration Rod
Thin slit should be inperfect focus, adjustoculars to same focalpoint
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 9/22
7/11/20
Parfocality• Microscope head
• pivots on the same axis as the slit projector
• Both come to focus at the same plane, the focal plane
• When changing the magnification, the focal plane is notchanged
• Slit projector and both eyepieces,
• at all magnifications,
• focus in the same plane
• are parfocal
• If this doesn’t happen with your slit lamp, it requires
adjustment or repair
Parfocal vs Decentered
Parfocal vs Decentered
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 10/22
7/11/20
Decentration
The Slit ProjectorSlit Beam Adjustment
• When the light beam is wide with no slit, we call theillumination “Broad Beam”
• Two knife edges moving together cause a slit to form,narrowing until the edges meet and occlude the light
• The height of the slit is variable as well
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 11/22
7/11/20
QuickTime™ and a
H.264 decompressor are needed to see this picture.
QuickTime™ and a
H.264 decompressor are needed to see this picture.
Slit Beam Height Adjustment
Video Video
• The height of the slit is variable as well
• Different schemes to vary height
• Useful for making measurements
Vertical (Haag-Streit andSimilar)
Turn knob here
Read scale for height here
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 12/22
7/11/20
Slit Beam Width Adjustment
QuickTime™ and aH.264 decompressor
are needed to see this p icture.
Haag-Streit
Width Adjustment
Illumination
• A rheostat (variable resistor) controls thebrightness of the illumination (brighter isbetter!)
Joystick and Lock
• Up-Down
• Right-Left
• Focus In-Focus OutLock
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 13/22
7/11/20
Slit Lamp Overdrive
• An extra burst of light power isavailable for specular microscopy insome older slit lamps (Zeiss)
The Power Surge Effect
• Overusing high illumination willcause early or immediate bulbfailure
Poor Light Intensity
• Neutral density filters may be in theway, and may need to be switched
off (Haag Streit)
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 14/22
7/11/20
Know Your Equipment! Slit Lamp Examof the Donor
• Most important exam of donorcornea
• Limited donor history in some
cases
• Detects ocular disease
• Detects previous eye surgery ortrauma
• Duty of technician and surgeon
Whole EyeExamination
• Penlight for in-situ
• Slit Lamp required if enucleation
• Uncap eye jar
• Wet the cornea with sterile BSS
• Tip jar and examine
• Prior to laboratory excision
• Best view of prior surgery
•YAG PI(Laser)
•Surgical PI
Thoughts During Exam
• Transplantable quality?
• Previous surgery may be OK• Refractive Surgery
• RK, AK, PRK, LASIK, TK
•Cataract surgery
• Glaucoma surgery
• Laser iridotomy*
• May save corneal storage media if grosslyunacceptable during whole eye exam
LASIK Donor
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 15/22
7/11/20
Slit Lamp TrainingTechniques
• Bright illumination, ambient darkness is sometimes essential
• Vary your illumination angles, generally use 350-450
• Swing the illuminator through its full arc (CSI flashlight)
• USE 40x mag for specular reflection
• Posterior illumination
QuickTime™ and a
DV/DVCPRO - NTSC decompress or are needed to see this picture.
Illumination -Overview
• Diffuse
• Direct focal
• Specular reflection
• Retroillumination
• Sclerotic scatter• Indirect
• Diffuse PosteriorDiffuse Broad beam Slit beam
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 16/22
7/11/20
Diffuse Illumination
• Uniform light of large area
• Overview of cornea
• Useful for gross abnormalities
Overview
• Rim Size, Shape
• Foreign Material
• Extraneous anatomical parts
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 17/22
7/11/20
Contact Lens
Surgical
Peripheral
Iridectomy
Corneal Transplant
Direct Focal Illumination
• Basis for biomicroscopy• Light’s focal point coincides with microscope’s focal point
• Tissue reflects, absorbs, transmits, and scatters light
• Can pinpoint findings in layers
• Parallelpiped (box/curved cube)
• Optic Section (knife like cross section)
Optical Block
• Oblique light incidence gives: “Optical
Block” or “Parallelpiped Prism”
• Narrow “slit” light beam pinpoints
depth and details
parallelpiped
lens
cornea
aqueous flare
Back
Front
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 18/22
7/11/20
Keratic Precipitates
Specular Reflection
• Means reflection through a mirror
• Look to side of dazzling light tosee endothelium
•
Can see cell outlines & guttata• Can estimate cell count
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 19/22
7/11/20
Retro-illumination
• Microscope’s focal point andlight’s focal point are are ondifferent spots
• Good for epithelial edema, KP,delicate scars, and bloodvessels
Light focused here
Microscope focused here
Corneal Cap
Removal withLens Implant
and Iris
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 20/22
7/11/20
2
Sclerotic Scatter
• Use decentered,
focused beam
• Direct at limbus
• Light disperses
• Total Internal reflection
• Good for diffuse scars
Sclerotic Scatter
EKC – EpidemicKeratoconjunctivitis
Foreign Bodies
Sclerotic Scatter:Epithelial Abrasion
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 21/22
7/11/20
2
Indirect Retroillumination Indirect/ObliqueIllumination
• Elements of sclerotic scatter andretroillumination
Focus medium to narrow beam adjacent to
observation area, e.g., scar
Place light source at wide angle tomicroscope
Broad Beam Illumination
7/28/2019 Slit Lamp Microscopy Lecture
http://slidepdf.com/reader/full/slit-lamp-microscopy-lecture 22/22
7/11/20
Radial Keratotomy4-16 incisions Tangential
Thin
SlitAlvarGullstrand