Slit Lamp Training Tim Buckley Product Manager

Basics Definition and Applications 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.

Basics Design 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

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

Basics Design 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

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

Basic Functions of the Slit Lamp Slit Width narrow slit circle shaped, if fully opened slit width is adjusted continuously

Basic Functions of the Slit Lamp Slit Length short slit long slit slit length is adjusted in steps and continuously

Basic Functions of the Slit Lamp Slit Rotation vertical slit horizontal slit vertical slit slit rotation can be adjusted continuously by ±90°

Basic Functions of the Slit Lamp Slit Decentration decentered slit slit can be decentered continuously by ±4°

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

Forms of direct Illumination Types of Illumination Forms of direct Illumination

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

Types of Illumination Direct Diffuse Illumination IOL iris supported anterior chamber lens in diffuse illumination Bildquelle: Universitäts-Augenklinik Jena

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

Types of Illumination Direct Focal Illumination - Optic Section Cataract anterior cortical opacities, nucleosclerosis and posterior opacities Bildquelle: www.atlasophthalmology.com

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

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

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

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

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

Types of Illumination Tangential Illumination Iris Iris in tangential illumination

α

Types of Illumination Specular Illumination 0° α 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

Types of Illumination Specular Illumination 0° α Types of Illumination Specular Illumination endothelial cells endothelial cell layer magnified ca. 192x Bildquelle: Carl Zeiss Meditec

Forms of indirect Illumination Types of Illumination Forms of indirect Illumination

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

Types of Illumination Indirect focal Illumination no example

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

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

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

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

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)

Types of Illumination Retro-Illumination from the Lens no example

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

Types of Illumination Retro-Illumination from the Fundus Aniridia missing iris and zonular cataract made visible by retro-ilumination Bildquelle: www.atlasophthalmology.com

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

Types of Illumination Iris-Transillumination Albinism Iris-Transillumination shows the light transmission of the iris Bildquelle: www.atlasophthalmology.com

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

Types of Illumination Sclerotic Scatters corneal scar corneal scarring after infection Bildquelle: www.atlasophthalmology.com

Fundus Observation and Gonioscopy

Fundus Observation and Gonioscopy 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 Fundus Image Microscope Bildquelle: www.ocular-instruments.com

Fundus Observation and Gonioscopy 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 Bildquelle: www.ocular-instruments.com

Fundus Observation and Gonioscopy Gonioscopy 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 Bildquelle: www.ocular-instruments.com

Fundus Observation and Gonioscopy Gonioscopy Three mirror contact glass Goldmann contact glass central lens: posterior pole 73° mirror: equator 67° mirror: ora serrata 59° mirror: anterior chamber angle 73° mirror Bildquelle: www.ocular-instruments.com

Fundus Observation and Gonioscopy Gonioscopy Three mirror contact glass Goldmann contact glass central lens: posterior pole 73° mirror: equator 67° mirror: ora serrata 59° mirror: anterior chamber angle 67° mirror Bildquelle: www.ocular-instruments.com

Fundus Observation and Gonioscopy Gonioscopy Three mirror contact glass Goldmann contact glass central lens: posterior pole 73° mirror: equator 67° mirror: ora serrata 59° mirror: anterior chamber angle 59° mirror Bildquelle: www.ocular-instruments.com

Fundus Observation and Gonioscopy Example: Fundus retinal scar microscope Bildquelle: UAK Jena / Carl Zeiss

Fundus Observation and Gonioscopy Example: Anterior Chamber Angle blood in chamber angle vessels in chamber angle

Examination using Fluorescein

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

Applanation Tonometry

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

Applanation Tonometry measuring figures a: applanation force too low b: correct setting c: applanation force too high

Length and Angle Measurement

Längen- und Winkelmessung Length and Angle Measurement Diameter of cornea and pupil height of conjunctival folds anterior chamber depth toric contact lenses

Redfree Examination

Redfree Examination Objects with high portion of red (e.g. fundus, vessels) contrast enhancement through green filter