Slit lamp biomicroscope

Slit-lamp biomicroscope

1. DEPT. OF OPTHALMOLOGY
SHER-E-BANGLA MEDICAL COLLEGE HOSPITAL, BARISAL.
DR. MD. NURUL ISLAM
DO STUDENT
SESSION – JULY, 2013
25-09-2014

2. INTRODUCTION

3. THE SLIT-LAMP BIOMICROSCOPE is a high-power
binocular microscope with a slit-shaped illumination
source, specially designed for viewing the different
optically transparent or translucent tissues of the eye.

It enhances the examination by :
Excellent image quality
Binocular stereoscopic view
Flexible illumination
Flexible magnification
Providing room for specialized attachments and lenses
for detailed examination and diagnostic tests

4. The science of examination with a slit lamp is
called Biomicroscopy as it allows in vivo study
of living tissues at high magnification.
Cont…

5. HISTORICAL LANDMARKS

6. •1911, the first concept of slit-lamp was
introduced by ALLVAR GULLSTRAND, it was
named as “Large reflection-free
ophthalmoscope” manufactured by Zeiss.
Prof. Allvar Gullstrand Large Gullstrand Opthalmoscope (1911)

7. •1919, VOGT introduced KOEHLER illumination
system to Gullstrand slit-lamp.
•1930, LETZ introduced telescopic loupe built
on the principle of Galilean Telescope which
helps in increase working distance.
Haag-Streit-1920 Bausch & Lomb slit lamp (1926)
Cont…

8. •1933, GOLDANN developed three control
element for cross-slide stage and also
common swivel axis for microscope and
illumination system in HAAG-STREIT Slit-lamp.
•1938, Joystick was added to Haag-streit.
Haag-Streit-1933
Haag-Streit-1936
Cont…

9. •1950, LITTMANN with ZIESS combined joystick control
from Goldmann, illumination path from Comberg prism
instrument and also added stereo telescope system
with magnification changer.
Cont…
Zeiss slit lamp (Littmann) (1950) Haag-Streit-1959

10. Fig. : Modern slit-lamp
Cont…
•Onward modern slit-lamp system began to
come into light.

11. TYPES

12. •On the basis of illumination system it is of 2 types :
1.Zeiss type
In the Zeiss type the illumination
comes from below

13. 2. Haag-streit type
In the Haag Streit type the
illumination comes from above
Cont…

14. •On the basis of compound microscope system it
is also 2 types :
1.The Grenough type
Flip lever to change
magnification
Cont…

15. 2. The Galilean changer type
Knob to change
magnification (3 or 5 step)
Cont…

16. Also different types of HAND-HELD slit-lamp
devices available for –
•Handicap
•Infant
•Bedbound patients
Cont…

17. OPTICAL PRINCIPLES

18. Illumination system Principle :
Kohler illumination principle is used in
both Zeiss & Haag-streit type illumination
system.
The light filament (F) is imaged on to
the objective lens (O) but the
mechanical slit (MS) is imaged on to the
patient’s eye (S)

19. Microscope system Principle :
The eyepiece (Ocular) uses
Astronomical telescope system.
Here two convex lenses used one in front
of other separated by the distance of their
focal length.
Fig. : Slit-lamp biomicroscope optical principles

20. A Galilean telescope system is
used for even higher and
changeable magnification.
Here a convex and a concave lens is used
in line separated by the distance of their
focal length.
Cont…
Fig. : Slit-lamp biomicroscope optical principles

21. Both telescope systems produce
inverse image of an object so an
inverting prism named Porro-
Abbe prism is used to produce
right way erect image.
Here two triangular prisms use the total
internal reflection principle of optics.
Cont…
Porro-Abbe Prism
Fig. : Slit-lamp biomicroscope optical principles

22. The telescope system provide considerable
distance between the microscope and the
patient’s eye, so that certain maneuver like
foreign body removal from the cornea or using
extra lenses for fundus examination can be
done.
Cont…

23. Parfocality : The point at which the microscope is
focused corresponds to the point on which the light is
focused, this coupling effect is called parfocality.
This is achieved by the microscope and the illumination
system, having a common focal plane and their common
axis of rotation also lies in that focal plane.
Cont…

24. PARTS OF THE SLIT-LAMP

25. Basic Design :
1.Mechanical system
2.Illumination system
3.Biomicroscope /Observation system
Associated instruments :
•Applanation Tonometer
•Gonioscopic Lens
•Fundoscopy Lens
•Micrometer Eyepieces
•Image archiving device
•Laser delivery system

26. It concern with :
•Positioning & adjustment of patient and observer
•Maneuvering the illumination and microscope
system together with joystick
•Providing base to other parts
Mechanical system :
Basic 3 parts :
1.Motorized table (Base)
2.Patient positioning frame
3.Joystick

27. Parts of mechanical system :

Cont…
Fixation target
Chin rest
adjustment
knob
Joystick
Power switch
Table height
adjustment
Forehead
band
Canthus
alignment
Chin rest
Hand grip
for patient
Lock for slit
lamp base
Low friction
plate

28. Provides a bright, evenly illuminated, finely focused,
adjustable slit of light at the eye.

Contains the following components:
•Light source
•Condenser lens system
•Slit and other diaphragms
•Filters
•Projection lens
•Reflecting mirror or prisms

Illumination system :

29. Parts of illumination system :
Cont…
Scale for slit
height
Slit height
control
Inclined
mirror
Latch to tilt
light column
Light
source
Filter
control
Centering
screw
Slit width
control

30. •Essentially these are compound microscopes
composed of optical elements providing enlarged
right way stereoscopic image to observer.

•Provides larger working distance in front of
microscope for manipulation on patient’s eye.

•Magnification changer for detail view.


Observation system :

31. Parts of observation system :
Cont…
Eyepiece
Marked ring for
Adjustment of
examiner’s
refractive error
Prism housing
Knob to
change
magnification
Objective lens

32. Associated instruments :

33. CLINICAL PROCEDURE

34. Prerequisites :
•Switch on power & unlock base screw
•Cleaning the forehead band
•Changing paper strip from chinrest
•Comfortable sitting of pt. and the
examiner
•Counseling the patient
•Proper positioning of the pt.
•Target fixation
•Adjust eyepieces to correct for
examiner’s refractive error and
interpupillary distance
•Children may need to stand, or they
can sit on parent’s lap or kneel on a
stable chair
Fig. Correct positioning at the slit lamp.

35. Chronology for slit-lamp examination :
Eyelids
Eyelid
margins
Tear film
Conjunctiva Cornea
Aqueous
humor
Iris Lens
Vitreous
(ant.)

36. Illumination techniques :
Slit Width control knob:

Narrow to fully open slit
illumination achieved
by rotating this knob

37. Illumination techniques :
Slit height control knob :
Short to long slit
illumination achieved
by rotating this knob

Cont…

38. Illumination techniques :
Slit angle rotation :
Cont…

39. Illumination techniques :
Tilting light column :
Illumination column
can be tilted 5-20°,
with vertical axis
which gives extra
plane and minimize
reflection during
posterior segment
examination with
condensing lens.
Cont…

40. Illumination methods :
Direct illumination
•Direct diffused illumination
•Direct focal illumination
i.Parallelepiped
ii.Optical section
iii.Conical beam
•Specular reflection
•Tangential illumination
Indirect illumination
•Indirect proximal illumination
•Retro-illumination
•Sclerotic scatter
Oscillatory illumination

41. Direct diffused illumination :
•illumination of the eye with a
broad, unfocused light beam
•directed obliquely between 30-45
0

•magnification 6x to 10x
Application :
•General gross overview of eyelids,
lashes, conjunctiva, sclera, pattern
of redness, iris, pupil, gross
pathology, ant capsule of lens
Cont…

42. Direct diffused illumination :
Cont…

43. Direct focal illumination :
•Illumination and observation are
focused in the same plane
•slit width narrow to broad
•Illumination angle 45° to 60°
•Magnification 10x-40x
Application :
•Cornea in detail
•Anterior chamber
•Crystalline lens
•Anterior part of vitreous
•Grading cell and flare in anterior
chamber
Cont…

44. Direct focal illumination :
Cont…

45. Direct focal illumination :
i.Parallelepiped
•Slit width 2-4 mm
obliquely focusing on
the cornea so that a
quadrilateral block of
light illuminate the
cornea
Application :
•To examine corneal
surface, stroma
•To ascertain depth
(FB, abration)



Cont…

46. Direct focal illumination :
ii.Optical section
•Slit width 1mm or less
•Illumination angle 45-60°
or more
•High illumination &
magnification
Application:
•Corneal depth, layers,
scars, vessels
•Lens opacity
Cont…
1. Tear film 2. Epithelium 3. Ant. Stroma
4. Post. Stroma 5. Descemet’s mem. &
Endothelium

47. Direct focal illumination :
iii.Conical beam
•Assessment of particles
floating in the A/C
•Narrow, short & bright slit of
light
•45°-60° light source directed
to pupil
•Magnification 16x-25x
Application :
•Inflammatory cells, flare,
pigmented cells, metabolic
wastes
Principle : Tyndall phenomenon

Cont…

48. Specular reflection :
•Angle of incidence = angle of
reflection
•Observation and illumination system
have same angle with perpendicular
axis to each other
•Slit width < 4mm
•The light reflected from the anterior
or posterior corneal surface
•Best view with one eye
Application :
•assessment of surfaces
Corneal epithelium
Corneal endothelium
Lens surface
•assessment of tear film
Cont…
Corneal endothelium

49. Tangential illumination :
•A narrow light beam is projected
almost parallel along the
structure to be observed
•Elevated structures are visible by
shadowing
•Illumination angle 90°
•Magnification 10-25x
Application :
•elevated abnormities or
changes in the iris
•tumors, cysts
Cont…

50. Indirect illumination :
•The beam is focused in an area
adjacent to ocular tissue to be
observed
•Decentered beam
•Illumination 2 to 4mm slit
•Magnification: Low to medium
(depending upon object size)
Application:
•infiltrates
•corneal scars
•deposits
•epithelial and stromal defects
Cont…

51. Indirect illumination :
Cont…

52. Retro-illumination :
•Light reflected on iris or fundus
•Microscope focused on cornea
•Two types: direct and indirect

Application :
For better visualization of
•Epithelial cysts
•Keratic precipitates
•Small blood vessels
•Small scar

Cont…

53. Direct retro-illumination :
•Observed feature is viewed in
direct pathway of reflected
light
•with this illumination findings
are made visible with high
contrast
•medium slit width 2 to 4mm
•Illumination angle 45-60°
Application :
•Infiltrations, small scars,
corneal vessels, etc.
Cont…

54. Indirect retro-illumination :
•Observer at right angle to the
observed structures
•Illumination angle greatly
reduced or increased
•Feature on the cornea is
viewed against a dark
background
•medium slit width 2 to 4mm
Application :
•Infiltrations, small scars,
corneal vessels, micro
cysts, vacuoles
Cont…

55. Retro-illumination :
Cont…
Indirectly
illuminated
Vacuole
Direct retro-
illumination

56. •This technique is used to observe
media clarities and opacities.
•The pupil is dilated
•the slit beam and microscope are
made co-axial and light strikes
the fundus and creates a glow
behind the opacity in the media
•The media opacity creates a
shadow in the glow
Applications
•abnormities in the
anterior vitreous, lens,
anterior chamber, cornea
Cont…
Retro-Illumination from the Fundus :

57. Sclerotic scatter :
•Light incident on the limbus
with 2-4mm slit at an angle of
45° - 60°
•Decentered slit
•The microscope focused
centrally
•Total internal reflection of the
incoming light at inner corneal
boundaries (endothelium and
epithelium)
Applications
•scars, foreign bodies, corneal
defects
•irregularities in the cornea
Cont…
Fig. : Corneal scar

58. Iris-transillumination :
•Transillumination of the iris
by indirect light reflected
from the fundus
•Mid dilated pupil (3 to
4mm)
•Illumination and
observation at coaxial
position
Applications
•Visualization of defects
of the pigment layer of
the iris
Cont…
Fig. : Transillumination in Albinism

59. Oscillatory illumination :
•Moves the beam (usually an optical section) from
nasal to temporal limbus
•Viewed alternately by direct and indirect
illumination
•Often possible to see minute objects or filaments,
specially in the aqueous
•Reveals subtle areas of corneal thinning.
Cont…

60. Van Herrick’s Technique :
•Used to evaluate anterior chamber angle without
gonioscopy
•Narrow slit beam close to limbus with Illumination angle
60°
•Medium magnification
Principle :
•Compare the width of cornea seen by optical section with the
dark section seen between ant. surface of iris & back of
cornea
Interpretation :
Grade 4 – open anterior chamber angle 1:1 ratio
Grade 3 – open anterior chamber angle 1:2 ratio
Grade 2– narrow anterior chamber angle1:4 ratio
Grade 1– risky narrow anterior chamber angle less than 1:4 ratio
Grade 0– closed anterior chamber

61. Van Herrick’s Technique : to assess anterior chamber angle
Cont…

62. Filters :
•White filter
•Overview of ocular surface tissues
•Examining intraocular structures


•Cobalt blue filter
•Coneal abrasion, ulcer
•Applanation tonometry


•Red free filter
•Rose-bengal staining

63. Applanation Tonometer :
The Goldmann Applanation Tonometer is the most
common tonometer that usually mounted on the standard slit-
lamp biomicroscope.
It’s easy to use and measure the IOP of a seated patient
with high accuracy in most clinical situations.

Parts :
1.Tonometer tip (biprism)
2.Metal rod
3.Tonometer housing
4.Force adjustment knob
Associated instruments :

64. Principle :
•Applanated force (AF) equals
the intraocular pressure (IOP)
•diameter of the applanated
area: 3.06 mm here
counteracting forces of
corneal rigidity and capillary
attraction cancel each other

Application :
•Measurement of intraocular
pressure (IOP)

Cont…

65. Procedure :
1.Proper positioning of the patient
2.Instill topical anesthetic and
flurescein in pt.‘s eye
3.Place the cobalt blue filter with
broad slit illumination at 60-90°
angle
4.The dial is preset between 1 and 2
(i.e. 10–20 mmHg)
5.Prism is advanced until it just
touches the apex of the cornea
6.Viewing into the oculars a pattern
of two semicircle will appear which
represent the fluorescein-stained
tear film touching the prism
Cont…

66. Procedure :
7.Then gently rotate the force
adjustment knob of tonometer
to align the inner margins of the
semicircles
8.The reading on the dial,
multiplied by 10, gives the IOP.
Modern digital display system
provides actual reading without
multiplication
9.Repeat the procedure for other
eye
10.At last wash B/E with antibiotic
eye drop

Cont…
Video clip : GAT

67. Fundus Observation and Gonioscopy :
•Different types of Contact and Non-contact lenses used for
examination, diagnostic and therapeutic purpose in
fundoscopy and gonioscopy
•With classic three mirror Goldmann lens post. Segment and
irido corneal angle can examined simultaneously

68. Cont…
Fundoscopy :
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 coupling liquid
(Hypromellose 0.3%)
•Coaxial angle (0°)
•Illumination – low with 2-4 mm
slit
•Magnification – 10-16 x

69. Cont…
Non-contact lenses :
•Additional tool for fundus
observation with the slit lamp
•Mostly indirect; upside-down
and mirror image of the
fundus (convex optics)
•non contact
Required:
•dilated pupil
•Coaxial angle (0°)
•Illumination - low with 2-4mm
slit
•Magnification – 10-16 x

Fundoscopy :

70. Cont…
Fundus view through 90D non-contact lens :

71. Cont…
Goldmann 3-Mirror gonioscopic lens :





•Procedure same as contact fundus lens
Observation :
•Central lens (0) : Posterior pole
•73° mirror (1) : Equator
•67° mirror (2) : Ora serrata
•59° mirror (3) : Iridocorneal angle

Gonioscopy :

72. Cont…
Application :
•Grading of A/C angle width
(Shaffer system)
•Peripheral anterior synechiae
•Neovascularization
•Hyperpigmentation
•Trauma
Angle recession
Trabecular dialysis
Cyclodialysis
Foreign bodies
•Blood in the Schlemm canal
Gonioscopy :
Fig.: Shaffer system grading
Fig.: Blood in chamber angle
Fig.: Neovascularization

73. •Slit-lamps have the
capability of providing
laser delivery with a
conjunct laser system
installed on it
•Lasers are used for the
treatment procedures like
photocoagulation,
iridotomy or capsulotomy
•Commonly delivered lasers
– Nd:YAG
Laser delivery system with slit-lamp :
Fig.: Laser system mounted Slit-lamp

74. The slit lamp is one of the most commonly
used and valuable diagnostic instruments
for an ophthalmologist of today.

So user level care & maintenance is very
much important to get optimum
performance & long life from it.

75. Video clip : Slit-lamp demonstration

77. •Clinical ophthalmology A systemic approach - Jack J Kanski - 7
th
ed.
•OPHTHALMIC OPTICS – Professor M.A. Matin 2
nd
ed.
•Clinical Optics – Andrw R. Elkington 3
rd
ed.
•BASIC OPHTHALMOLOGY – Professor Md. Shamsul Haque – 2
nd
ed.
•AMERICAN ACADEMY OF OPHTHALMOLOGY (2012-2013) – Sec.-3
•AMERICAN ACADEMY OF OPHTHALMOLOGY (2012-2013) – Sec.-8
•Essentials of Ophthalmology – Samar K Basak – 5
th
ed.
•Internet –
•https://www.google.com - Search Links
•http://en.wikipedia.org
•https://www.youtube.com