3. Here comes your slit lamp...
...and with it comes your
RESPONSIBILITY
4. Background
The name
SLIT : A narrow slit beam of very bright light
LAMP : produced by a lamp (illumination
system)
BIO : to view the biological structure (of
eye)
MICROSCOPE : under magnification with a
microscope
5. Overview
Instrument uniquely designed to give a magnified
three dimensional view of the eye and its structures
for quantitative measurements for documentation.
Because the slit lamp provides a binocular view, the
location of abnormalities can be determined with great
precision.
The instrument combines variable magnification with
controlled illumination.
In simple, to make a magnified tour of the eye.
7. History Mystery
Alivar Gullstrand
(5 June 1862 – 28 July 1930)
Nobel prize in Medicine and
Physiology (1911) for developing
slit lamp biomicroscope.
Vogt (1919) : Specular
Microscopy
Various modification by Kohler,
Goldmann,
16. Optics
It works on the same principle as a compound
microscope.
The objective lens (+22 D) is towards the patient,
whose eye forms the object. The objective lens
consists of two planoconvex lenses with their
convexities facing towards each other.
The eyepiece is +10 to +14 D and is towards the
examiner.
The illuminating system can be adjusted to vary the
width, height and angle of incidence of the light beam.
25. 2. Illumination system
lamp housing unit
slit width and height control
neutral density filter
cobalt blue light
red-free (green) filter
field size control
diffuser
prism.
26. 3. Mechanical system
Motorized table (Base)
Patient positioning frame
Joystick
forehead rest
chin rest
fixation target
power supply unit
locking controls.
29. 4. Height
– adjustable slit height
5. Angle
– variable angle formed with the observation
system
– rotation of the prism or mirror enables
observation with an alternate illumination
technique (especially an indirect method).
33. What the Patient Needs to
Know
Instruction to patients:
This instrument is a microscope used to magnify the
structures of the eye.
Please keep your chin in the cup with your teeth
together and your forehead against the bar. Try not to
lean back. The microscope comes close to your face
but will not touch your eye.
Sometimes the light is bright. Unless specifically told
not to, you may blink at any time.
Try to keep both eyes open.
This is just a light, not a laser or a camera.
34. How to start?
Focus the eye piece
Adjust the headrest
Position the fixation target
Decrease the room illumination
Start with diffuse illumination
35. Order of Examination
Tears
Lid margins/Lashes
Conjunctiva
Cornea
Anterior chamber
Iris
Lens
Anterior vitreous
38. Keypoints
Patient education is an important aspect of the slit lamp
exam.
A comfortable patient is a more cooperative patient.
Before beginning, adjust the ocular power and pupillary
distance
(PD).
Using lower voltage settings preserves bulb life.
Manipulate the microscope with one hand on the light
source
and the other hand on the joystick.
Developing and following an examination protocol will help
ensure quality patient care.
43. 2. Direct Illumination
Observation and illumination systems are
focused
at the same point.
Vary angle of
illumination
Low to high
magnification
Vary width and height
of light source
44. 2.1 Optic Section:
Slit width 1mm or less
Illumination angle 45-60° or more
High illumination & magnification
Application:
Corneal depth, layers, scars, vessels, Lens opacity
45. 2.2 Parallelepiped: wider beam
Slit width 2-4 mm obliquely focusing
quadrilateral block of light illuminate the
cornea
Application
To examine corneal epithelial,
stroma
To ascertain depth (FB, abrasion),
breakdown, lens surface and endothelium.
46. 2.3 Conical Beam:
Narrow, short & bright slit of light
45°-60° light source directed to pupil
Magnification 16x-25x
Application :
Inflammatory cells, flare, pigmented cells, metabolic
wastes
Assessment of particles floating in the A/C
47.
48. 3.Indirect Illumination
Observation and illumination systems are not
focused at the same point.
Focal light beam is directed adjacent to the
area of observation.
Vary angle of illumination
Slit beam is offset
Vary beam width
Low to high magnification
50. 4.Retro-illumination
Object of interest is illuminated by light
reflected
from the structures behind it.
Vary angle of illumination
Moderately wide beam
Slit beam is offset
Medium to high magnification
Reflected light from iris or
fundus
52. 5. Specular Reflection
Angle of incidence = angle of reflection
Slit width < 4mm
Magnification 35x
Best view with one eye
53. Application :
Assessment of surfaces
Corneal epithelium
Corneal endothelium
Lens surface
Assessment of tear film
54. 6. Sclerotic scatter
Light incident on the limbus with 2-4mm slit at
an angle of 45° - 60°
The microscope focused centrally
Total internal reflection of the incoming light at
inner corneal boundaries (endothelium and
epithelium)
55. Applications
Scars, foreign bodies, corneal
defects
Irregularities in the cornea
Localized epithelial oedema.
56. 7. Tangential
A narrow light beam is projected almost
parallel along the structure to be observed
Elevated structures are visible by shadowing
Illumination angle 70-90°
Magnification 10-25x
57. Application :
Elevated abnormities or changes in the iris
Tumors, cysts
58. Key Points
An appreciation of what is normal is necessary
before one can identify that which is abnormal.
Documenting that a structure is normal is just
as important as notating irregularities.
There are variations of normal that you will
learn as you continue to examine eyes with
the slit lamp.
60. Filters
a) Open aperture
b) Heat absorption screen: decreases patient discomfort
c) Grey filter: decreases maximum brightness for photosensitive patients
d) Red free filter- enhances blood vessel and haemorrhage
e) Empty space for extra filter
63. Slit lamp is the an important instrument for an
eye health personnel (treat it as an asset)
User level care & maintenance is very much
important to get optimum performance & long
life from it.
An careful eye examination can make a
difference in someones life.
Slit lamp examination is an artof
science.....Practice, practice practice