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Slit Lamp Training
Tim BuckleyProduct Manager
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BasicsDefinition and Applications
Definition
The purpose of a slit lamp is the biomicroscopy of the patient‘s eye under different lighting conditions. The slit lamp projects a bright and homogenously illuminated slit onto the eye which is variable in length, width, angle and light intensity.
Fields of Application
The primary field of application is the anterior eye segment (cornea, anterior chamber, lens, anterior vitreous).
Using additional optics enables the user to also examine the posterior eye segment as well as the anterior chamber angle.
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BasicsDesign Principles
• components: microscope, slit projector, instrument base
• carrier arms for microscope and slit projector can be swiveled around a common axis
• swivelling axis is located in the focal plane of microscope and slit projector
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BasicsDesign Principles - Biomicroscope
• Zeiss slit lamps:Galilei type microscope
– common front objective– parallel beam path– 3 or 5 magnification steps
• other manufacturers also offer Greenough type microscopes
– two separate, tilted beam paths
– only 2 magnification steps– very few accessories
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BasicsDesign Principles - Slit Projector
• purpose: to project a slit image focused on the patient‘s eye
• the slit image is variable in length, width and angle
• light source: usually halogen (high color temperature)
• filters: blue, green (redfree), diffusor, heat absorbing filter
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BasicsDesign Principles - Instrument Base
• functional coupling of carrier arms of microscope and slit projector
• slit projector and stereo microscope can independantly be swiveled around a common axis
• Axis is located below patient’s eye
• both slit image and observation are in focus in the axial plane
• three-dimensional positioning by joystick
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Basic Functions of the Slit LampSlit Width
narrow slit circle shaped, if
fully opened
slit width is adjusted continuously
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Basic Functions of the Slit LampSlit Length
short slit long slit
slit length is adjusted in steps and
continuously
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Basic Functions of the Slit LampSlit Rotation
vertical slit horizontal slit vertical slit
slit rotation can be adjusted continuously by ±90°
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Basic Functions of the Slit LampSlit Decentration
decentered slit
slit can be decentered continuously by ±4°
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Basic Functions of the Slit LampTilting Prism
angle of incidence 0° angle of incidence 20°
tilting prism can be tilted by 0° to 20° continuously
positions 0°, 5°, 10°, 15°, 20° indexed
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Types of Illumination
Forms of direct Illumination
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Types of IlluminationDirect Diffuse Illumination
Principle• illumination of the eye with a
broad, unfocused light beam• usage of diffusor• microscope positioned at 0°• magnification 5x ... 12x
Applications• Overview• general assessment of anterior
eye, eye lids• assessment of contact lenses
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Types of IlluminationDirect Diffuse Illumination
IOL
iris supported anterior chamber lens in
diffuse illumination
Bildquelle: Universitäts-Augenklinik Jena
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Types of IlluminationDirect Focal Illumination - Optic Section
Principle• Illumination and observation are
focused in the same plane• slit width ca. 0,1 to 0,3mm
Applications• mainly findings in the cornea and
lens• opacities, scars, vessels• good perception of the depth of
findings
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Types of IlluminationDirect Focal Illumination - Optic Section
Cataract
anterior cortical opacities, nucleosclerosis
and posterior opacities
Bildquelle: www.atlasophthalmology.com
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Types of IlluminationDirect Focal Illumination - Optic Disc
Principle• Illumination and observation are
focused in the same plane• slit width ca. 2 to 4mm
Applications• mainly findings in the cornea and
lens• opacities, scars, vessels• good perception of shape and size
of findings
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Types of IlluminationDirect Focal Illumination - Optic Disc
Cyst on Pupillary Edge
Cyst on pupillary edge stems from usage
of too strong miotica
Bildquelle: www.atlasophthalmology.com
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Types of IlluminationDirect Focal Illumination - Conical Beam
Principle• assessment of particles floating in
the anterior chamber by illuminating with a light beam
• Tyndall‘s phenomenon• pinpoint illumination 0,3 - 0,5mm
Applications• assessment of particles in
aqueaous humor• inflammation cells, pigmented
cells, metabolic waste
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Types of IlluminationDirect Focal Illumination - Conical Beam
cells in anterior chamber
cells in anterior chamber as a sign of
uveitis
Bildquelle: www.atlasophthalmology.com
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Types of IlluminationTangential Illumination
Principle• a narrow light beam is projected
almost parallel along the structure to be observed
• elevated structures are visible by shadowing
Applications• elevated abnormities or changes in
the iris• tumors, cysts
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Types of IlluminationTangential Illumination
Iris
Iris in tangential illumination
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α α
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Types of IlluminationSpecular Illumination
Principle• angle of incidence = angle of
reflection• observation and illumination have
same angle to perpendicular axis• slit width < 4mm
Applications• assessment of surfaces • assessment of tear film• endothelial cell layer
0°
α α
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Types of IlluminationSpecular Illumination
endothelial cells
endothelial cell layer magnified ca. 192x
0°
α α
Bildquelle: Carl Zeiss Meditec
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Types of Illumination
Forms of indirect Illumination
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Types of IlluminationIndirect focal Illumination
Principle• illumination by stray light• slit is slightly decentered so that
stray light is created in direct neighbourhood of the finding
• slit width ca. 2 to 4mm
Applications• mainly corneal lesions and scars
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Types of IlluminationIndirect focal Illumination
no example
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Types of IlluminationDirect Retro-Illumination from the Iris
Principle• Illumination of the finding with
indirect light rflected from the iris• observation with light background• medium slit width, ca. 2 to 4mm
Applications• Infiltrations, small scars, corneal
vessels, micro cysts, vacuoles• with this illumination findings are
made visible with high contrast
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Types of IlluminationDirect Retro-Illumination from the Iris
Keratitis Superficialis Punctata
finding after moderate cauterization by
acid, defects of epithelium and conjunctiva
have been stained with bengal rose
Bildquelle: www.atlasophthalmology.com
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Types of IlluminationIndirect Retro-Illumination from the Iris
Principle• Illumination of the finding with
indirect light reflected from the iris• observation with dark background• medium slit width, ca. 2 to 4mm
Applications• Infiltrations, small scars, corneal
vessels, micro cysts, vacuoles
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Types of IlluminationIndirect Retro-Illumination from the Iris
Keratitis Punctata, contact lens wearer
multiple erosions of the central cornea due
to inappropriate contact lens fittingBildquelle: www.atlasophthalmology.com
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Types of IlluminationRetro-Illumination from the Lens
Principle• Illumination of the finding with
indirect light reflected from the lens• observation with light background• medium slit width, ca. 2 to 4mm
Applications• corneal defects, foreign bodies,
scars• (type of illumination not frequently
used)
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Types of IlluminationRetro-Illumination from the Lens
no example
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Types of IlluminationRetro-Illumination from the Fundus
Principle• Illumination of the finding with
indirect light reflected from the fundus
• observation with red/yellowish background
• dilated pupil
Applications• abnormities in the anterior
vitreous, lens, anterior chamber, cornea
• findings are visible like silhouettes
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Types of IlluminationRetro-Illumination from the Fundus
Aniridia
missing iris and zonular cataract made
visible by retro-iluminationBildquelle: www.atlasophthalmology.com
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Types of IlluminationIris-Transillumination
Principle• transillumination of the iris by
indirect light reflected from the fundus
• half dilated pupil (3 to 4mm)• Illumination and observation at ca.
0°
Applications• Visualization of defects of the
pigment layer of the iris
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Types of IlluminationIris-Transillumination
Albinism
Iris-Transillumination shows the light
transmission of the irisBildquelle: www.atlasophthalmology.com
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Types of IlluminationSclerotic Scatters
Principle• Illumination of the limbus region
with a broad light beam at an angle of 45° - 60°, decentered slit
• total reflection of the incoming light at inner corneal boundaries (endothelium and epithelium)
Applications• scars, foreign bodies, corneal
defects• irregularities in the cornea cause
straylight
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Types of IlluminationSclerotic Scatters
corneal scar
corneal scarring after infection
Bildquelle: www.atlasophthalmology.com
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Fundus Observation and Gonioscopy
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Fundus Observation and GonioscopyContact Glasses
Contact Glasses
• additional tool for fundus observation with the slit lamp
• mostly direct: erect and non mirrored image of the fundus
• required: dilated pupil, use of gliding liquid
Bildquelle: www.ocular-instruments.com
Microscope
Fundus Image
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Fundus Observation and GonioscopyLenses
Lenses
• additional tool for fundus observation with the slit lamp
• mostly indirect: upside-down and mirrored image of the fundus (convex optics)
• non contact
• required: dilated pupil
Bildquelle: www.ocular-instruments.com
microscope
Inverted fundus image
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Fundus Observation and GonioscopyGonioscopy
Three mirror contact glass
• Goldmann contact glass
• central lens: posterior pole
• 73° mirror: equator
• 67° mirror: ora serrata
• 59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
central lens
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Fundus Observation and GonioscopyGonioscopy
Three mirror contact glass
• Goldmann contact glass
• central lens: posterior pole
• 73° mirror: equator
• 67° mirror: ora serrata
• 59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
73° mirror
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Fundus Observation and GonioscopyGonioscopy
Three mirror contact glass
• Goldmann contact glass
• central lens: posterior pole
• 73° mirror: equator
• 67° mirror: ora serrata
• 59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
67° mirror
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Fundus Observation and GonioscopyGonioscopy
Three mirror contact glass
• Goldmann contact glass
• central lens: posterior pole
• 73° mirror: equator
• 67° mirror: ora serrata
• 59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
59° mirror
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Fundus Observation and GonioscopyExample: Fundus
retinal scar
Bildquelle: UAK Jena / Carl Zeiss
microscope
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Fundus Observation and GonioscopyExample: Anterior Chamber Angle
blood in chamber angle
vessels in chamber angle
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Examination using Fluorescein
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Examination using Fluorescein
Principle• Fluorescein is inserted into the
conjunctival sac and fills, for example, intracellular spaces
• dye is excited with blue light(λ 450 ... 500 nm)
• contrast reducing straylight is blocked with barrier filter (yellow filter λ > 530 nm)
Applications• corneal lesions / defects• contact lens fitting
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Applanation Tonometry
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Applanation Tonometry
Principle (according to Prof. Goldmann)
• diameter of the applanated area: 3,06 mm
• counteracting forces of corneal rigidity and capillary attraction cancel each other out
• applanated force (AF) equals the intraocular pressure (IOP)
Applications• measurement of intraocular
pressure
IOP AF
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Applanation Tonometry
measuring figures
a: applanation force
too low
b: correct setting
c: applanation force
too high
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Length and Angle Measurement
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Längen- und Winkelmessung
Length and Angle Measurement
• Diameter of cornea and pupil
• height of conjunctival folds
• anterior chamber depth
• toric contact lenses
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Redfree Examination
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Redfree Examination
• Objects with high portion of red (e.g. fundus, vessels)
• contrast enhancement through green filter