-1- slit lamp training tim buckley product manager

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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


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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


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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


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Types of IlluminationIndirect Retro-Illumination from the Iris


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


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


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


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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


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


central lens

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73° mirror

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67° mirror

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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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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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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

-1- slit lamp training tim buckley product manager

Documents

slit slit length

slit projector slide

slit lamp slit decentration

slit image

tangential illumination

illuminated slit

plane slit width

slit lamp projects