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SLIT LAMP BIOMICROSCOPE MOPB 021.pptx
- 1. SLIT LAMP BIOMICROSCOP E MOPB 021 NSHABALALA/ M MAKOMBELA
- 2. CONTENT 01 Introduction 02 Instrumentation 03Principles 04 Set-up 05 Procedures 06 Vital stains 07 Maintenance 4/23/2023 2
- 3.
- 4. • Instrument consistingof a high intensity light source that can be focused to shine as a slit • Used in conjunction with a microscope • Magnified, stereoscopic, non-invasive and detailed view of the anterior segment of the eye • In conjunction with some accessory optical lenses provides detailed examination of Anterior chamber angle (Gonioscopy), Measurement of IOP (GAT) Retina (78/90D) INTRODUCTION
- 5. INTRODUCTION TWO TYPES 1. Zeissslitlamp biomicroscope • Light source is at the base 4/23/2023 5
- 6. INTRODUCTION 2. Haag-Streit slitlamp biomicroscope •Light source is at the top 4/23/2023 6
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- 9. Operational components ofslit lamp biomicrope consist of: • Illumination system • Observation system • Mechanical system 4/23/2023 9 INSTRUMENTATIO N
- 10. ILLUMINATION SYSTEM • A bright,focal source of light with a slit mechanism • Beam can be changes in intensity, width, direction or angle and colour during examination • Condensing lens system • Planoconvex lenses with their convex surface in apposition • Slit and other diapharm • Height and width of slit can be varied by using knobs 4/23/2023 10
- 11. 4/23/2023 11 • Projectionlens • Forms an image of slit at eye • Keeps aberration of lens down & Increases the depth of focus of the slit • Reflecting mirrors and prisms • Filters • Yellow barrier, Red free, Neutral density, Cobalt blue & Diffuser ILLUMINATION SYSTEM
- 12. 4/23/2023 12 • Yellow •Allows better contrast when using fluorescein and cobalt filter • Red free (green) • Obscures anything that is red, blood vessels or haemorrhages appear black • Increases contrast, revealing path and pattern of inflamed blood vessels • Fleischer ring (Dark rings in peripheral cornea due to copper deposits) are viewed well with red free filter • Neutral density • Decreases maximum brightness for photosensitive patients ILLUMINATION SYSTEM
- 13. ILLUMINATION SYSTEM • Cobaltblue • Used together with fluorescein stain • The fluorescein dye absorbs blue light and emits green • Where corneal epithelium is broken or absent, dye is also absent • Used for Ocular staining, RGP lens fitting, Tear layer assessment, GAT • Diffuser • May be a flip-up filter placed on the illumination source used for general observations of the eye and adnexa 4/23/2023 13
- 14. FILTERS 4/23/2023 14 YELLOW, REDFREE, COBALT & DIFFUSER
- 15. 4/23/2023 15 • Compoundmicroscope composed of two optical elements 1. An objective lens, 2. An eyepiece • Presents enlarged image of near object and magnification obtained by multiplying power of the eyepieces with the power of the objective lens • e,.g eyepiece 5X mag and objective 2X mag = resultant of 10X mag • Prisms in objective and eye piece allow the image to NOT be inverted • Typically provide mag of 6x to 40x OBSERVATION SYSTEM
- 16. MECHANICAL SYSTEM • Joysticksystem allows focusing • Focussing is controlled by the joystick. it is designed to move laterally, axially and vertically. Vertical movement is achieved by rotating the joystick • Patient support system • Forehead rest and a vertically adjustable chin rest • Table height adjustment 4/23/2023 16
- 17. MECHANICAL SYSTEM • Mechanicalcoupling • Coupling of microscope and illumination system along a common axis of rotation that coincides their focal planes • Illumination and observation system can be moved away from eachother to change the angle of the incident light beam. • Ensures light falls on the point where the microscope is focused. • Fixation target • Movable target 4/23/2023 17
- 18. MECHANICAL SYSTEM • Magnification control •Pair of readily changeable objective lenses and two sets of eyepieces • On/off switch and illumination control 4/23/2023 18
- 19.
- 20. • The biomicroscopehas 2 eyepieces which offer the observer a binocular, stereoscopic and magnified view of the eye. The light produced by the lamp can be made into a "slit" or beam of very bright light that is focused on the eye. PRINCIPLE
- 21.
- 22. SET-UP • Clean thechin and forehead rest with an alcohol swab • Position the patient by adjusting the table and chin rest height such that patient’s outer canthus aligns with the mark • Decrease the room illumination • Position the fixation target • Focus the eyepiece • Halogen light is used in most techniques
- 23.
- 24. Indirect illumination Sclerotic scatter Retro-illumination Proximalillumination Transillumination 4/23/2023 24 Diffuse illumination Direct illumination Optic section Parallilepiped Specular reflection Conical beam Tangential
- 25. DIFFUSE ILLUMINATION PURPOSE Generalview of anterior eye including lids, lashes, sclera, cornea, iris and pupil. Gross pathology and view of media opacities Contact lens fitting and tear tests SLIT SIZE Widest width and height ANGLE Between 30 to 45 degrees MAGNIFICATION Low to high ILLUMINATION Low to medium FILTER Diffuser
- 26. DIFFUSE ILLUMINATIO N • Procedure • Sweepacross lids and lashes with patient’s eye closed. • Sweep across the eye and assess the anterior ocular surface for abnormalities
- 27. DIRECT ILLUMINATION: Refers toviewing of structures within the focussed light beam
- 28. OPTIC SECTION PURPOSE Cutsa very thin slice of the cornea allowing of corneal layer examination Location and depth of corneal lesion, scar, foreign body Localize Nerve fibers, blood vessels, infiltrates and AC depth (Van Herrick) SLIT SIZE Very narrow, (<0.25mm) ANGLE Between 30 to 60 degrees MAGNIFICATION Low to high ILLUMINATION Low to high
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- 30. VAN HERRICK PURPOSE Gradedepth of AC to estimate the openness of the angle SLIT SIZE Narrow (1mm to 3mm) ANGLE At 60 degrees MAGNIFICATION Low to high ILLUMINATION Low to high
- 31. VAN HERRICK Procedure • Opticsection of limbal cornea, with beam at 60 degrees • Compare corneal section and width of the shadow adjacent to it • Slit width on cornea is used as reference for the chamber angles
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- 33. VAN HERRICK GRADE RELATIONSHIP BETWEENSLIT & AC DEPTH INTERPRETATION 4 1:1 or higher Angle closure very unlikely (35-45°) 3 1:1/2 Angle closure unlikely (20-35°) 2 1:1/4 Angle closure possible (20°) 1 1: <1/4 Angle closure likely (10°) 0 Closed Angle closure (0°)
- 34. PARALLELEPIPED PURPOSE Detect andexamine corneal structures and defects, depth and extent of corneal, scarring or FB. Corneal striae that develop when corneal oedema occurs with hydrogel CL wear and in keratoconus SLIT SIZE 1 to 2mm wide ANGLE Approx 45 degrees MAGNIFICATION Medium to high (preferably) ILLUMINATION Low to medium
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- 36. SPECULAR REFLECTION PURPOSE Visualisecorneal endothelium, lens surfaces, corneal epithelium and tear film SLIT SIZE Parallelipiped with height like purkinje image ANGLE Coaxial, Illumination 30 degrees in one direction, observation source 30 degrees in other direction MAGNIFICATION High ILLUMINATION
- 37. SPECULAR REFLECTION Procedure • Startby focussing an optic section at 30 degrees on the cornea, placing it on the bright reflex seen • Move observation system 30 degrees in the other direction (coaxial) • Increase width (parallelipipe) and magnification • 3 reflexes should be present i.e bright reflection of the tear film, a dim reflection from the endothelium and a blurred image of the light source
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- 39. SPECULAR REFLECTION • Underspecular reflection anterior corneal surface appears as white uniform surface and corneal endothelium takes on a mosaic pattern • Focus finely on the dim section to observe the endothelial mosaic (best observed through one ocular), and reduce height to match mosaic • Tear film debris and the lipid layer thickness can also be
- 40. CONICAL BEAM PURPOSE Detectaqueous flares and cells in anterior chamber SLIT SIZE Small circular or square spot of light ANGLE 45- 60 degrees temporal and through pupil MAGNIFICATION 16X to 25X ILLUMINATION High
- 41. CONICAL BEAM Procedure • Narrowvertical height of a parallelipiped beam to produce a small circular or square spot of light. • Beam is focused between cornea and anterior lens surface and dark zone between cornea and anterior lens observed. • Principle is similar to that of a ray of sunlight streaming through a room, illuminating airborne dust particles Tyndall phenomenon
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- 43. CONICAL BEAM • Tyndallphenomenon: Cells, pigment or proteins in the aqueous humour reflect the light like a faint fog visualized by adjusting slit illuminator to smallest circular beam and is projected through the ant. chamber. • Most useful when examining the transparency of anterior chamber for evidence of floating cells and flares seen in anterior uveitis • Aqueous flares- yellowish particles (proteins) • Cells- whitish reflections (WBCs)
- 44. TANGENTIAL ILLUMINATION PURPOSE Observesurface texture, ant and posterior cornea Uniformity of the iris without dilation Anterior lens (esp usefule for pseudoexfolation) SLIT SIZE Medium width, moderate height ANGLE 90 degrees, creates shadows for any elevation MAGNIFICATION 10X to 25X ILLUMINATION Low to medium
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- 46. INDIRECT ILLUMINATION: Refers toviewing of structures not within the focussed light beam
- 47. 4/23/2023 47 INDIRECT ILLUMINATION PURPOSEExamination of objects in direct vicinity of corneal areas of reduced transparency e,g, infiltrates, corneal scars, deposits, epithelial and stromal defects SLIT SIZE Narrow to medium slit beam ANGLE Decentred MAGNIFICATION Approx. 12X
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- 49. 4/23/2023 49 • Usedto evaluate the optical qualities of a structure • The light strikes the object of interest from a point behind the object and is then reflected back to the observer • A vertical slit beam 1-4mm wide can be used. • Place object of regard against a bright background allowing object to appear dark or black. • Used most often in searching for keratic precipitates and other debris on corneal endothelium • The crystalline lens can also be retroilluminated for viewing of water clefts and vacuoles of anterior lens and posterior subcapsular cataract RETRO ILLUMINATION
- 50. 4/23/2023 50 DIRECT RETROILLUMINATION(FROM IRIS) PURPOSE Used to view corneal pathology SLIT SIZE Moderately wide slit ANGLE 45 degree MAGNIFICATION 16x to 25x PROCEDURE A moderately wide slit beam is aimed towards the iris directly behind the corneal anomaly and microscope is directed straight ahead .
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- 52. 4/23/2023 52 INDIRECT RETROILLUMINATION (FROMIRIS) PURPOSE Used to view corneal pathology SLIT SIZE Moderately wide slit ANGLE 45 degree MAGNIFICATION 16x to 25x PROCEDURE Beam is directed to an area of the iris bordering the portion of iris behind the pathology and microscope is directed straight ahead providing dark background allowing corneal opacities to be viewed with more contrast
- 53. INDIRECT RETROILLUMINATION (FROMIRIS) 4/23/2023 53
- 54. 4/23/2023 54 RETRO ILLUMINATION(FROM FUNDUS) PURPOSE Visualize media clarity and opacities SLIT SIZE Wide slit beam ANGLE Almost coaxial position MAGNIFICATION 10X to 16X PROCEDURE The light is directed so that it strikes the fundus and creates a glow behind the abnormality creating a shadow in the light. The wide slit beam is decentered and adjusted to a half circle by using the slit width. The decentred slit beam is projected near the pupil margin through a dilated pupil. Microscope directly focused on the pathology and media (cornea, lens, vitreous) is viewed
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- 56. 4/23/2023 56 SCLEROTIC SCATTER PURPOSEVisualize corneal changes or abnormalities. E.g Central corneal epithelial edema, Corneal abrasions, Corneal opacities SLIT SIZE Tall and wide beam ANGLE 40-60 degree MAGNIFICATION 10X to 16X PROCEDURE A tall, wide beam is directed onto the limbal area causing cornea to take on total internal reflection. This produces a halo glow of light around the limbus as the light is transmitted around the cornea. Corneal changes or abnormalities can be visualized by reflecting the scattered light
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- 58. 4/23/2023 58 PROXIMAL ILLUMINATION PURPOSETo observe internal detail, depth, and density. E.g corneal opacities (edema, infiltrates, vessels, foreign bodies), lens, iris SLIT SIZE Short and narrow slit PROCEDURE Place the beam at the border of the structure or pathology, the light will be scattered into the surrounding tissue, creating a light background that highlights the edges of the abnormality. The light from behind may reflect through, allowing detailed examination of the internal structure of the pathology
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- 60. 4/23/2023 60 TRANSILLUMINATION PURPOSE Visualizeiris defects (they will glow with the orange light reflected from the fundus) SLIT SIZE full circle beam equal to the size of the pupil ANGLE light source directly in line with the microscope MAGNIFICATION 10X to 16X PROCEDURE The iris (iris transillumination) is evaluated by how light passes through it, takes advantage of the red reflex. The pupil must be at mid mydriasis (3to 4 mm when light stimulated). Project the light through the pupil and into the eye and focus the microscope on the iris. Normally the iris pigment absorbs the light, but pigmentation defects let the red fundus light pass through
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- 63. • Staining ofcells or tissues in living state/ a stain that can be applied on living cells without killing them • Slit lamp is an esential tool in examining the cornea and the conjuctiva after staining them with different vital stains • The stains include:- (SELF STUDY) - Sodium fuorescein - Rose bengal - Lissamine green VITAL STAINS
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- 65. • It shouldbe kept in a room free of dust, humidity and direct sun exposure • It should be switched off and covered at the end of an examination • Do not touch the lenses, mirror and glass portion of the bulb • Remove accidental fingerprints with a tissue paper • Always operate the instrument in low voltage setting i.e. in lower illumination to increase the lifespan of the instrument MAINTENANCE
Editor's Notes
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