The document outlines a lecture on slit lamp examination, emphasizing its critical role in assessing the anterior segment of the eye. It details the components, types, and various applications of slit lamps, as well as techniques for illumination and magnification. The importance of slit lamp design, including its mechanical and optical systems, is also discussed to enhance understanding of its functionality in clinical practice.

1. BAREILLY INTERNATIONAL UNIVERSITY, BAREILLY
A
LECTURE
ON
“ Slit Lamp Examination”
DELIVERED BY
MS. GULAFSHAN SAIFI
ASSISTANT PROFESSOR
DEPARTMENT OF OPTOMETRY
FACULTY OF PARAMEDICAL SCIENCES BAREILLY
Rohilkhand Medical College And Hospital ,Campus , Pilibhit Bypass Road Bareilly ,U.P -
243006

2. TODAY’S GOALS
• By the end of today’s lecture, you should be able to…
• List the uses of the slit lamp biomicroscope
• Identify the main components of the slit lamp; be able to
operate these components
• Discuss and perform a series of basic illumination and
magnification techniques
• A second lecture will follow where we talk about
combining these techniques into a routine and look at
some examples

3. WHY SLIT LAMPS ARE SO GREAT
 Slit lamp assessment is considered to be the gold
standard device for the assessment of the anterior
segment of the eye in clinical practice
 This is because they provide…
 Excellent image quality
 Stereoscopic image
 Flexible illumination
 Flexible magnification
 Therefore there are many different uses
 Even more when attachments are added

4. TYPES
There are 2 types of slit lamp:-
(a) Zeiss slit lamp (b) Haag Streit slit lamp
In Zeiss type light source is at base of the instrument while in Haag
streit type it is at the top of the instrument.

5. WHAT CAN WE USE THEM FOR?
ON THEIR OWN
 Routine examination of anterior
segment
 Adnexa through to anterior vitreous
 Problem-based examination of
anterior segment
 Contact lens examination
 Assessment of anterior chamber
depth and angle
WITH ACCESSORIES
 Gonioscopy
 Fundoscopy
 Ocular photography
 Contact tonometry (Goldmann)
 Pachymetry
 Corneal sensitivity measurements
(aesthiometry)
 Laser photocoagulation

6. BASIC DESIGN
 Viewing arm
 Biomicroscope
 Adjustable focus eyepieces
 Magnification dial
• Illumination arm
 The “slit lamp”
 Slit size, shape and filter controls
 Variable size, shape, colour and brightness
• Biomicroscope and illumination are mechanically
coupled around central pivot point (copivotal)
 Both focus at the same point (parfocal)
 Both arms can swing independently 180º along horizontal – there
is a scale in degrees
 Both always central regardless of angle (isocentric)
Moveable base plate and joystick control

7. PRINCIPLE
• A narrow beam is produced by the slit lamp which is observed by
the examiner.

8. OBSERVATION SYSTEM
• An objective lens :- consist of 2 plano convex lenses, together they
form
+22 D
• An eyepiece :- a lens of +10 D and it provide a good stereopsis.
• Prism :- image formed by a slit lamp is inverted, to reinverted the
image a pair of prism is used.

9. ILLUMINATION SYSTEM
• Light source
• Condenser lens system:- consist
of a plano convex lenses
• Slit and other diaphragm
• Filters
• Projection lens
• Reflecting mirror or prism

10. MECHANICAL SYSTEM
• Joystick
• Up and down movement
arrangement
• Patient support arranegemnt
• Fixation target

11. MAGNIFICATION

12. MAGNIFICATION
• Slit lamps provide variable magnification
• Lower magnifications are used for general assessment
and orientation
• Higher magnifications are used for detailed
inspections of areas of interest
• There are several ways to do this
• Common methods: Littmann-Galilean telescope and zoom
systems
• Less common methods: Change the eyepieces and/or change
the objective lens

13. LITTMANN-GALILEAN
TELESCOPE METHOD
 A separate optical system is placed in between the
eyepiece and the objective
 It consists of a rotating drum that house 2 Galilean
telescopes plus a pair of empty slots
 Optics refresher: Galilean telescopes consist of a positive and
negative lens that provide magnification based on the lens powers
and their separation
 It is easy to identify whether the slit lamp you are using
has this inside
 The magnification dial will click into place as you turn it, and there
will be numbers on the dial that correspond to the magnification in
each position

14. A GALILEAN TELESCOPE
Parallel light enters and exits.
Magnification is typically the
intended outcome.
However, if you look from the other
side, the image will be minified.

15.  Two telescopes produce two
magnifications
 Mag highest when the
convex lens is near
objective
 Reversal of these two
telescopes produces two
further minifications
 No telescope provides 5th
option

16. ZOOM SYSTEMS
• This tends to be found on high-end Nikon, Topcon
and Zeiss instruments
• Magnification can vary between 7x to ~ 40X
• I find that the image quality is not as good with zoom
magnification

17. CHANGE EYEPIECES OR OBJECTIVE
EYEPIECES
 Often two sets provided with slit
lamp
 Typical values 10x, 12.5x, 15x or 20x
 Inconvenient so rarely used
 Generally unnecessary on modern
slit lamps
OBJECTIVE
 Flip arrangement for rapid change
 Usually only two options due to
space confinements
 Typical values are 1x and 2x
Lever

18. ILLUMINATION
THE SLIT LAMP

19. WHAT MAKES A GOOD SLIT?
• A good slit needs to be
• Bright
• Evenly illuminated
• Finely focused
• Have well defined, straight edges
• Flexible in terms of size, shape, colour and intensity
• The illumination also needs to
• Provide good colour rendering to detect subtle colour changes

20. SLIT WIDTH
• Continuously variable (0 to 12-14mm)
• May be graduated to allow
measurement
• Narrow slits are used to “slice” through
the cornea to determine depth or
thickness
• Wide slits are used to inspect surfaces

21. SLIT HEIGHT
 May be continuous or set to fixed
heights
 Usually a combination of the two
 May be graduated to allow for
measurement
 Long slits are used to view most
structures in front of the pupil, while
short slits pass through the pupil
much better
 Short slit also used to assess the
clarity of the anterior chamber

22. SLIT ORIENTATION
• Achieved by rotating lamp
housing