Slit Lamp Training
Tim Buckley
Product Manager
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Basics
Definition 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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Basics
Design Principles
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•
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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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Basics
Design 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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Basics
Design Principles - Slit Projector
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•
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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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Basics
Design 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 Lamp
Slit Width
narrow slit
circle shaped, if
fully opened
slit width is adjusted continuously
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Basic Functions of the Slit Lamp
Slit Length
short slit
long slit
slit length is adjusted in steps and
continuously
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Basic Functions of the Slit Lamp
Slit Rotation
vertical slit
horizontal slit
vertical slit
slit rotation can be adjusted continuously by ±90°
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Basic Functions of the Slit Lamp
Slit Decentration
decentered slit
slit can be decentered continuously by ±4°
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Basic Functions of the Slit Lamp
Tilting 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 Illumination
Direct 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 Illumination
Direct Diffuse Illumination
IOL
iris supported anterior chamber lens in
diffuse illumination
Bildquelle: Universitäts-Augenklinik Jena
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Types of Illumination
Direct 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 Illumination
Direct Focal Illumination - Optic Section
Cataract
anterior cortical opacities, nucleosclerosis
and posterior opacities
Bildquelle: www.atlasophthalmology.com
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Types of Illumination
Direct 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 Illumination
Direct 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 Illumination
Direct 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 Illumination
Direct 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 Illumination
Tangential 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 Illumination
Tangential Illumination
Iris
Iris in tangential illumination
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α
α
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Types of Illumination
Specular 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
α
α
0°
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Types of Illumination
Specular Illumination
α
endothelial cells
α
0°
endothelial cell layer magnified ca. 192x
Bildquelle: Carl Zeiss Meditec
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Types of Illumination
Forms of indirect Illumination
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Types of Illumination
Indirect 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 Illumination
Indirect focal Illumination
no example
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Types of Illumination
Direct 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 Illumination
Direct 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 Illumination
Indirect 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 Illumination
Indirect Retro-Illumination from the Iris
Keratitis Punctata, contact lens wearer
multiple erosions of the central cornea due
to inappropriate contact lens fitting
Bildquelle: www.atlasophthalmology.com
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Types of Illumination
Retro-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 Illumination
Retro-Illumination from the Lens
no example
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Types of Illumination
Retro-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 Illumination
Retro-Illumination from the Fundus
Aniridia
missing iris and zonular cataract made
visible by retro-ilumination
Bildquelle: www.atlasophthalmology.com
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Types of Illumination
Iris-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 Illumination
Iris-Transillumination
Albinism
Iris-Transillumination shows the light
transmission of the iris
Bildquelle: www.atlasophthalmology.com
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Types of Illumination
Sclerotic 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 Illumination
Sclerotic 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 Gonioscopy
Contact Glasses
Fundus Image
Contact Glasses
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•
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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
Microscope
Bildquelle: www.ocular-instruments.com
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Fundus Observation and Gonioscopy
Lenses
Inverted fundus image
Lenses
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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
microscope
Bildquelle: www.ocular-instruments.com
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Fundus Observation and Gonioscopy
Gonioscopy
central lens
Three mirror contact glass
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Goldmann contact glass
central lens: posterior pole
73° mirror: equator
67° mirror: ora serrata
59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
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Fundus Observation and Gonioscopy
Gonioscopy
73° mirror
Three mirror contact glass
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Goldmann contact glass
central lens: posterior pole
73° mirror: equator
67° mirror: ora serrata
59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
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Fundus Observation and Gonioscopy
Gonioscopy
67° mirror
Three mirror contact glass
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Goldmann contact glass
central lens: posterior pole
73° mirror: equator
67° mirror: ora serrata
59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
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Fundus Observation and Gonioscopy
Gonioscopy
59° mirror
Three mirror contact glass
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•
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Goldmann contact glass
central lens: posterior pole
73° mirror: equator
67° mirror: ora serrata
59° mirror: anterior chamber angle
Bildquelle: www.ocular-instruments.com
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Fundus Observation and Gonioscopy
Example: Fundus
microscope
retinal scar
Bildquelle: UAK Jena / Carl Zeiss
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Fundus Observation and Gonioscopy
Example: 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
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Objects with high portion of red (e.g.
fundus, vessels)
contrast enhancement through green
filter
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