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1. SLIT LAMP
BIOMICROSCOP
E
MOPB 021
N SHABALALA/ M MAKOMBELA

2. CONTENT
01 Introduction
02 Instrumentation
03 Principles
04 Set-up
05 Procedures
06 Vital stains
07 Maintenance
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3. 01 INTRODUCTION

4. • Instrument consisting of 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. Zeiss slitlamp
biomicroscope
• Light source is at the
base
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6. INTRODUCTION
2. Haag-Streit slitlamp
biomicroscope
• Light source is at the
top
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7. 02 INSTRUMENTATION

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9. Operational components of slit
lamp biomicrope consist of:
• Illumination system
• Observation system
• Mechanical system
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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
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• Projection lens
• 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

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• 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
• Cobalt blue
• 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
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14. FILTERS
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YELLOW, RED FREE, COBALT & DIFFUSER

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• Compound microscope 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
• Joystick system  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
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17. MECHANICAL SYSTEM
• Mechanical coupling
• 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
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18. MECHANICAL
SYSTEM
• Magnification control
• Pair of readily changeable
objective lenses and two
sets of eyepieces
• On/off switch and illumination
control
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19. 03 PRINCIPLES

20. • The biomicroscope has 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. 04 SET-UP

22. SET-UP
• Clean the chin 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. 05 PROCEDURES

24. Indirect illumination
Sclerotic scatter
Retro-illumination
Proximal illumination
Transillumination
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 Diffuse illumination
Direct illumination
 Optic section
 Parallilepiped
 Specular reflection
 Conical beam
 Tangential

25. DIFFUSE ILLUMINATION
PURPOSE General view 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
• Sweep across lids and lashes with patient’s eye
closed.
• Sweep across the eye and assess the anterior
ocular surface for abnormalities

27. DIRECT ILLUMINATION:
Refers to viewing of structures within the focussed light
beam

28. OPTIC SECTION
PURPOSE Cuts a 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

29. OPTIC SECTION

30. VAN HERRICK
PURPOSE Grade depth 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
• Optic section 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

32. VAN HERRICK

33. VAN HERRICK
GRADE RELATIONSHIP
BETWEEN SLIT & 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 and examine 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

35. PARALLELEPIPED

36. SPECULAR REFLECTION
PURPOSE Visualise corneal 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
• Start by 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

38. SPECULAR REFLECTION

39. SPECULAR REFLECTION
• Under specular 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 Detect aqueous 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
• Narrow vertical 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

42. CONICAL
BEAM

43. CONICAL BEAM
• Tyndall phenomenon: 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 Observe surface 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

45. TANGENTIAL
ILLUMINATIO
N

46. INDIRECT ILLUMINATION:
Refers to viewing of structures not within the focussed
light beam

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INDIRECT ILLUMINATION
PURPOSE Examination 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

48. INDIRECT
ILLUMINATION
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49. 4/23/2023 49
• Used to 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

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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 .

51. DIRECT RETROILLUMINATION
(FROM IRIS)
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52. 4/23/2023 52
INDIRECT RETROILLUMINATION
(FROM IRIS)
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 (FROM IRIS)
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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

55. RETRO ILLUMINATION (FROM
FUNDUS)
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56. 4/23/2023 56
SCLEROTIC SCATTER
PURPOSE Visualize 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

57. SCLEROTIC
SCATTER
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58. 4/23/2023 58
PROXIMAL ILLUMINATION
PURPOSE To 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

59. PROXIMAL
ILLUMINATION
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60. 4/23/2023 60
TRANSILLUMINATION
PURPOSE Visualize iris 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

61. TRANSILLUMINATION
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62. 06 VITAL STAINS

63. • Staining of cells 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

64. 07 MAINTENANCE

65. • It should be 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