Post on 02-Apr-2018
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SLIT-LAMP BIOMICROSCOPY
The slit-lamp biomicroscope is an
important diagnostic instrument for
the examination of the anterior eye
structures as well as the retina.
Being able to proficiently use the
instrument is important. It use
critical in the fitting of contact
lenses.
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THE SLIT-LAMP BIOMICROSCOPE
The instrument is composed of two main components. The slit-lamp is the
light source and the controls to modify the size, shape, direction, color and
intensity of the light.
The biomicroscope is the microscope used to view the eye. The
magnification can be varied.
The accurate term for the instrument is the slit-lamp biomicroscope,however, it is usually called the slit-lamp or the biomicroscope.
Light source
microscope
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THE SLIT-LAMP BIOMICROSCOPE
Each brand of biomicroscope is slightly different. They have a switch to
turn the light source on. The intensity of the light source can be varied.
The control is often the same dial that turns the light source on or near itdepending on the make of the instrument.
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THE SLIT-LAMP BIOMICROSCOPE
The slit-lamp biomicroscope can be moved in relation to the
patient using the joy stick for focusing and bringingstructures into view. Other parts of the instrument are the
head and chin rest to hold the patient still and the adjustable
table to hold and adjust the height the instrument for doctor
and patient comfort.
Joy stick to
position instrument
To adjust the
Vertical height
of the instrument
To adjust the heightof the chinrest
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THE SLIT-LAMP BIOMICROSCOPE
The instrument is designed such that when you use the joystick to move
the instrument towards and away from the patient to focus structureswheel moves on a track. When the instrument moves side to side it
moves along a rod. It can be locked so that one can not move it with the
joystick by tightening down a knob on the rod. It should be locked when
not in use or when moving the instrument.
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THE SLIT-LAMP BIOMICROSCOPE
The angle between the light source and microscope can be changed by just
moving the arms that hold the light and microscope. They can be locked in
place if desired, however, during the examination the angle between the two
are being changed to obtain the proper views.
Light source and microscope
arms that can be rotated
independently.
Knobs to lock arms in place,
usually used when
biomicroscope in not in use
or being moved.
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THE SLIT-LAMP BIOMICROSCOPE
Before examining a patient become familiar with the controls.
The width of the light beam can be adjusted by a control on the slit-lamp.
The light beam can also be moved back and forth horizontally. In addition the
light beam can be rotated away from vertical.
Red arrows-slit width control
Green arrows-slit height and filter control
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THE SLIT-LAMP BIOMICROSCOPE
Different instruments have different controls to
change the magnification. In some cases they alsohave a second set of eyepieces that can be used to
change the magnifications.
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THE SLIT-LAMP BIOMICROSCOPE
The light beam and the microscope both have to be focused at
the same point. A focusing rod is put in place. The light source,
a narrow beam, is positioned on the rod. This should be at the
click position of the light source. When looking through the
microscope the light source should be in the center of your view
and in focus.
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THE SLIT-LAMP BIOMICROSCOPE
You must focus the eyepieces for your eyes. With a narrow
beam of light on the focusing rod, look through thebiomicroscope. Looking through only one eyepiece at time,
rotate the eyepiece counter-clockwise until the light beam
appears blurred, then rotate it clockwise until the light beam
just comes into focus.
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PATIENT POSITIONING
Clean the headrest and chin rest with an alcohol swab
before putting the patient behind the instrument.
Some units have paper sheets on the chinrest where a
sheet can be removed between patients.
Before starting the exam the patient must be
comfortably seated behind the instrument with their
chin on the chin rest and head tight against the head
rest. The height of the instrument and chin rest
should be adjusted so the patients eyes are aligned
with the alignment marks on the head rest.
Alignment
mark
Incorrect, the
forehead is not
against theheadrest.
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PATIENT FIXATION
You need to control the patients fixation. The instruments have a
fixation light that can be placed in front of the patient andpositioned so the patient is looking in the desired position. This
may cause the patient to accommodate and converge on the
fixation light causing some discomfort.
Often an easier and quicker way is to have the patient just look at
your ear or a point on the biomicroscope. Then you can just ask
the patient to look down, up, left or right as needed.
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ROUNTINE FOR EXAMINING THE ANTERIOR SEGMENT
In order to be sure you do not miss any anomaly you must getinto the habit of using a set routine. A common order of
examination is:
Lids and lashesConjunctiva and cornea
Instillation of fluorescein and BUT measurement
Eversion of the lids
Anterior chamber and angle measurement
Iris
Crystalline lens
Anterior vitreous
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DIRECT AND DIFFUSE ILLUMINATION
The lids and anterior ocular structures are examined
with the slit lamp beam wide open. This called directillumination. To obtain an even wider view a diffuser
can be placed in front of the light source to give diffuse
illumination.
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LID EXAMINATION
The skin of the lids should be examined for any lumps or bumps
or skin lesions. It is best to start by having the patient close theireyes and scan the lids starting with the upper lid from temporal to
nasal followed by the lower lid. It is important to get in a routine
sequence of examination so you do not miss anything.
Low (7X to 10X) to moderate (10X to 16X) magnification is used
when examining the lids with higher magnifications only used to
study an abnormality. It too high magnification is used you will
miss some abnormalities.
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EXAMINATION OF THE LASHES
The lashes should be examinedfor abnormalities such blepharitis.
With blepharitis there will be
collarettes found at the base of
the lashes.
This photo shows nits (egg
sacs) from lice infestation of
the lashes.
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EXAMINATION OF THE LASHES
The lashes can also be missing. This is called
madaroisis.
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LID MARGINS
After examining the closed lids have the patient open their eyes and
examine the lid margins. You should see the normal structures suchas the meibomian gland openings on both the upper and lower lids.
The puncta (opening for the tears to exit the eye) can be seen at the
nasal side of the lid margin on the upper and lower lids.
Meibomian gland openings puncta
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LID MARGINS
The lid margins should be examined for injection, swelling,
lesions, plugged meibomian glands, chalazion or otheranomalies.
Plugged gland
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EYE MAKE-UP
It is common to see make-up along the lid margins. It can also
be seen in the tear film and may become embedded in the
palpebral conjunctiva. Make-up can create problems with
contact lens wear.
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EXAMINATION OF THE BULBAR CONJUNCTIVA
The conjunctiva visible within the palpebral opening without
pulling the lids back can next be inspected with diffuse
illumination. One should look for injection, dry spots, cysts,pigmentation, pingueculum, pterygium or other anomalies.
Any type of irritation, trauma or infection can cause injection of the
conjunctiva.
Injected conjunctivaNormal conjunctiva
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EXAMINATION OF THE BULBAR CONJUNCTIVA
This photo shows a nevus onthe conjunctiva.
This photo shows a pinquecula,
a raised area on the
conjunctiva that is fairly
common.
EXAMINATION OF THE SUPERIOR AND INFERIOR
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EXAMINATION OF THE SUPERIOR AND INFERIOR
BULBAR CONJUNCTIVA
The superior bulbar conjunctiva isexamined by having the patient
look down and gently pulling the
upper lid up.
The inferior bulbar conjunctiva
can likewise be examined by
having the patient look up and
pulling the lower lid down.
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EXAMINATION OF THE LIMBUS
It is important to examine the limbus, the junction between the
cornea and conjunctiva. A number of normal structures may bevisible including blood vessel loops, nerves, palisades of Vogt and
pigmentation.
A green filter can be used to
better visualize the blood vessels
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EXAMINATION OF THE LIMBUS
This photo shows the Palisades of Vogt which are often visible
with darkly pigmented patients. The palisades are radial
extensions of the sclera towards the cornea at the limbus with
epithelial cells 10 to 12 layers thick between them.
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EXAMINATION OF THE LIMBUS
This photo is of posterior
embryotoxon, an developmental
anomaly where Schwalbes ring
(collagenous tissue between the
end of Descemets membrane
and the trabecular meshwork)
extends further into the cornea
than normal
EXAMINATION OF THE CORNEA WITH
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EXAMINATION OF THE CORNEA WITH
DIRECT OR DIFFUSE ILLUMINATION
The cornea can be scanned with a wide beam direct or diffuse illumination to
detect anomalies.
Corneal scars, neovascularization, infiltrates, abrasions, foreign bodies and
other conditions can be seen.
Anomalies should not be confused with the reflection of the light source from
the surface of the cornea or from the surface of the crystalline lens.
reflection fromsurface of the cornea
reflection from surface of
the crystalline lens
Corneal scar
EXAMINATION OF THE CORNEA WITH
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EXAMINATION OF THE CORNEA WITH
DIRECT OR DIFFUSE ILLUMINATION
Arcus senilis is a build-up of cholesterol and other lipids in the
peripheral cornea. It appears as a whitish or yellowish ring just
inside the limbus. It is found in 60% of patients between 40 and 60
years old and almost all patients over 80.
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EXAMINATION OF THE TEAR FILM
Diffuse or a wide beam direct illumination can also be used to
inspect the tear film. Debris can be seen floating in the tear filmand the debris can increase in dry eye conditions, irritation and
infection.
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EXAMINATION OF THE TEAR FILM
Bubbles, also called frothing, can sometimes be seen in the tear
film, especially along the lid margins. This can indicatemeibomianitis.
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EXAMINATION OF THE TEAR FILM
Colored interference fringes may also beseen on the tear film over the cornea.
These are visible when the oily layer of the
tear film is thicker than normal.
These are most often seen just above thelower lid margin. By pressing on the
lower lid and forcing the oily material from
the meibomian glands, this will enhance
the fringes.
INSTILLATION OF FLUORESCEIN
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INSTILLATION OF FLUORESCEIN
Following a general overview of the visible portion of the anterior
segment and prior to significant manipulation of the lids, fluorescein
should be instilled to measure the break-up time of the tear film(B.U.T.), look for corneal staining, conjunctival staining and papillae.
The method of instilling fluorescein is important. The fluorescein
strip should be moistened with saline solution. Do not touch the tip
of the bottle to the strip. After putting a drop on the strip shake the
excess off prior to instilling it on the eye. You do not want to add
excessive solution t the eye, just the stain.
Correct
Incorrect-do
not touch strip to
bottle
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INSTILLATION OF FLUORESCEIN
To instill fluorescein, have the patient look down, rest your wrist on
the patients forehead and grasp the upper lid with the index finger
over the lashes. The patient should not be able to blink. With thepatient still looking down, pull the lid up and gently lay the flat side
of the strip against the conjunctiva. Do not rub the fluorescein strip
across the eye. Gently lift it off and release the lid.
Do not use a dry fluorescein strip or dab the fluorescein strip
against the lower lid as this unnecessarily irritates the patient and
causes reflex tearing.
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INSTILLATION OF FLUORESCEIN
Another method of instilling fluorescein is to have the patient look
up and while holding the lids instill the fluorescein on the inferior
conjunctiva.
The fluorescein strip will cause some staining of the conjunctival
which is normal. You should not touch the strip to the cornea as
this will cause the patient discomfort and staining of the cornea.
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FLUORESCEIN STAINING
Fluorescein is a water soluble stain that will stain the tear film and
any disruption of the ocular surface. It will show any breaks in theepithelium and be absorbed by cells which have damaged
membranes.
FLUORESCEIN STAINING
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FLUORESCEIN STAINING
Fluorescein staining can be
highlighted by the use of filters.
The biomicroscope has a cobalt(blue) filter that can be placed in
the light beam. The blue filter
enhances the visibility of the
stain.
The visibility of the staining can
be further enhanced by placing a
yellow filter (ie. a Wratten #12 or
Tiffin #2) over the objective of the
biomicroscope.
The top photo shows a filter being
placed over the objective. The
bottom photo shows some
different filters that can be used.
FLUORESCEIN STAINING
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FLUORESCEIN STAINING
The yellow filter filters out the
blue light to give better
visualization of the greenfluorescence of the fluorescein.
The top photo is with the yellow
filter in place.
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MEASURING THE TEAR FILM BREAK-UP TIME
The time it takes for the tear film to break-up following a blink is an
indication of the quality of the tear film. Immediately following theinstillation of fluorescein the B.U.T. should be measured. The room
lights should be out and filters in place. The patient is asked to blink
3 or 4 times and then to look straight ahead and not blink. The time
in seconds from the last blink until a dark spot or streak develops in
the tear film is the B.U.T. Do not hold the lids open.
TEAR FILM
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TEAR FILM
In addition to the light green staining of the tear film seen over the
corneal surface, the tears in the tear meniscus (also termed tearprism, lacrimal lake, or tear strip) along the lid margins is easily
seen. With dry eyes this tear meniscus is decreased in size and
may be essentially absent in places.
CORNEAL STAINING
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CORNEAL STAINING
If only the superficial epithelial cells are damaged, the
fluorescein staining will be limited to the area of damage. If the
full thickness of the epithelium is damaged, fluorescein will seepinto the stroma giving a larger area of staining. The borders will
not be as distinct since the fluorescein is slowly diffusing
through the stroma.
CORNEAL STAINING
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CORNEAL STAINING
Rubbing the cornea through the eyelid can cause an epithelial
mosaic staining pattern (Schweitzers Lines). This lasts only afew minutes.
CONJUNCTIVAL STAINING
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CONJUNCTIVAL STAINING
Using the wide beam or diffuse illumination and the filters, the
conjunctiva should be examined for staining. It is normal to haveareas of pooling of fluorescein, especially in older patients where
the conjunctiva is looser and more wrinkled.
Fluorescein pooling in
folds of the conjunctiva Spots of staining from drying
ROSE BENGAL STAINING
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ROSE BENGAL STAINING
Rose bengal stain is used to stain dead or degenerating cells as
well as mucous. It is used to show staining with dry eye patients.
It is supplied on strips like fluorescein or as a solution. Only asmall amount of stain is required. If too much is used it will be
uncomfortable. One must be careful as it will stain clothing and is
not as easily washed out as fluorescein. Another stain which
stains similar cells as rose bengal but is more comfortable is
lassime green.
PALPEBRAL CONJUNCTIVA EXAMINATION
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PALPEBRAL CONJUNCTIVA EXAMINATION
It is important to evert the upper lid and examine the palpebral
conjunctiva for papillae, cysts, concretions, foreign bodies,irritation and other anomalies. With the patient in the head rest,
have the patient look down and grasp the upper lid margin over
the lashes. With a cotton-tipped applicator or other stylus placed
at the upper lid sulcus (the fold in the upper lid) and lift the lid up
and evert it over the stylus.
HOLDING THE EVERTED LID FOR EXAMINATION
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HOLDING THE EVERTED LID FOR EXAMINATION
Hold the lid in the everted
position with your thumb and
examine the palpebral
conjunctiva with the
biomicroscope.
PALPEBRAL CONJUNCTIVA EXAMINATION
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PALPEBRAL CONJUNCTIVA EXAMINATION
The upper conjunctiva should be
smooth and not injected. A common
problem with contact lens wear is thedevelopment of papillae (raised areas
of inflammatory tissue). Each
papillae has a central blood vessel
stalk. With fluorescein it is easier to
detect the papillae.
PALPEBRAL CONJUNCTIVA EXAMINATION
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PALPEBRAL CONJUNCTIVA EXAMINATION
The lower conjunctiva should also be examined. Just pull down
the lid. Look for cysts, follicles, embedded make-up, concretions
or other anomalies.
concretionEmbedded make-up
CORNEAL EXAMINATION-SCLEROTIC SCATTER
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CORNEAL EXAMINATION SCLEROTIC SCATTER
An illumination called sclerotic
scatter is useful in detectingcentral corneal clouding (corneal
edema) created with rigid contact
lenses and other corneal opacities
such as scars, foreign bodies and
abrasions.
A light beam about 2 to 4 mm wide
is focused on the temporal limbus.
The light source should be rotated
such that it is off to the side of the
viewing area (the microscopefocused on the center of the
cornea and the light source on the
limbus). When properly set up the
limbus 180 degrees from the light
beam will glow.
PARALLELEPIPED
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PARALLELEPIPED
One of the most useful illuminations is the parallelepiped. This is a
relatively wide beam of light that illuminates a block of the cornea.
The microscope is directly in front of the patients cornea and the
light source is approximately 45 degrees from the straight ahead
position. Low to moderate magnification can be used to scan the
cornea with high magnification used to examine structures in
detail.
Width of beam
(front surface of cornea)
Back surface of the
cornea
Light reflected
off of the iris
CORNEAL EXAMINATION WITH THE PARALLELEPIPED
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CORNEAL EXAMINATION WITH THE PARALLELEPIPED
The corneal should be scanned with a parallelepiped as it is the
illumination that is used to detect and examine corneal structures
and defects.
Corneal nerve seen with
a wide parallepiped.
Pigment on the back of
the cornea seen with a
more narrow beam.
A corneal scar seen with
a relatively wide beam
CORNEAL EXAMINATION WITH THE PARALLELEPIPED
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CORNEAL EXAMINATION WITH THE PARALLELEPIPED
The parallelepiped can be used to detect corneal striae that
develop when corneal edema occurs with hydrogel lens wear, in
keratoconus and normally in some older patients.
They are seen as small, usually vertical, white lines deep in the
corneal stroma. They are best seen with high magnification. With
greater amounts of edema folds develop in the same area which
appear as dark lines.
striae
fold
CORNEAL EXAMINATION WITH THE OPTIC SECTION
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CORNEAL EXAMINATION WITH THE OPTIC SECTION
When scars, abrasions or other
anomalies are detected one often
wants to know how deep they go intothe cornea. This is when an optic
section is used. The optic section is
a very thin parallelepiped and
optically cuts a very thin slice of the
cornea. The distance from the front
and back of the section gives you the
location within the cornea.
The epithelium (front surface of the
cornea) gives a bright reflection. With
high magnification a speckle patter isseen within the normal stroma. The
back of the optic section is the
endothelium.
Front of cornea Back of cornea
CORNEAL EXAMINATION WITH THE OPTIC SECTION
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CORNEAL EXAMINATION WITH THE OPTIC SECTION
The top photo shows a corneal scar
with a wide beam of illumination.
The bottom photo shows an opticalsection through the scar indicating
the depth within the cornea-in this
case very superficial.
MEASURING THE SIZE OF DETAILS
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MEASURING THE SIZE OF DETAILS
It is important in following and
documenting conditions to accurately
measure them. The width or height of a
structure can be measured by using a spotof known diameter or a parallelepiped of
known width. Biomicroscope have a scale
on the light source that indicates the width
of the beam. They also have apertures of
different diameters that can be used.
It is also possible to have a reticule in the
eyepiece to make the measurement,
however, most biomicroscopes do not have
such a reticule.
MEASURING THE MOVMENT OF A CONTACT LENS
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MEASURING THE MOVMENT OF A CONTACT LENS
The amount of movement of a lens can be estimated by using a
spot of light of known size. For example with a soft lens, a spotsize of 0.2 mm to 1 mm can be used. The amount of movement of
the lens edge with a blink in relation to the spot size can be
determined.
RETRO AND INDIRECT ILLUMINATION
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RETRO AND INDIRECT ILLUMINATION
Many corneal defects are not easily seen
with direct illumination. Such things as
microcystic edema, microcysts andneovascularization are examples.
Retro-illumination is where a relatively
narrow beam (1-3 mm) is reflected off
the iris and the object of interest isviewed against the bright iris. If the
object is opaque it will appear dark.
Indirect is similar except you view the
area of the cornea next to the light beamhits the cornea and not against the
reflection from the iris. In practice both
are used more or less similtaneously.
RETRO AND INDIRECT ILLUMINATION
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These photos show an foreign
body in direct illumination (top)
and indirect illumination (bottom)
RETRO AND INDIRECT ILLUMINATION
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This photo shows microcystic
edema and vacuoles from
wearing a thick hydrogel contact
lens in retro illumination.
RETRO-ILLUMINATION
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Neovascularization (new vessel growth) near the limbus is
often difficult to visualize. Retro-illumination makes thevessels easier to see.
RETRO ILLUMINATION
RETRO-ILLUMINATION
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This photo shows epithelialmicrocysts (small dots) in the
corneal epithelium from the
wearing of an extended wear soft
contact lens. It is often easiest to
detect such small defects alongthe edge of the retro-illumination,
this is sometimes termed
marginal retro-illumination.
RETRO ILLUMINATION
RETRO-ILLUMINATION
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When the pupil is dilated, retro-illumination, can give a red reflex
against which corneal defects can be seen. The beam is passed
through the periphery of the pupil to obtain this view. This photoshows an area of localized edema.
RETRO ILLUMINATION
SPECULAR REFLECTION
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SPECULAR REFLECTION
Specular reflection is when the angle
between the light source and microscope
is such that a specular reflection isobtained from the cornea.
A bright reflection is obtained from the
surface of the cornea and a less bright
reflection form the posterior surface ofthe cornea. This illumination is obtained
by using a narrow parallelepiped and
placing the microscope directly in front of
the patients eye with the light source
approximately 45 degrees to the side.
The angle of the light should be moved
until a very bright reflection is obtained
from the corneal surface.
SPECULAR REFLECTION
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SPECULAR REFLECTION
Specular reflection is mainly used to
view the endothelium, the single layer
of cells on the back surface of thecornea. The highest magnification
available should be used. To view this
layer look just to the side of the bright
reflection from the font surface of the
cornea. If the parllelepiped is too wide
you will not be able to see the
endothelium. To view different areas
of the cornea have the patient change
their gaze as well as you changing the
angle of the microscope and light
source.
The endothelium will appear as a fine,
rough surface due to the individual
endothelial cells.
endothelium
reflection from the
front surface
SPECULAR REFLECTION
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SPECULAR REFLECTION
Endothelium guttata, polymegethism (variation in size of the
cells) and dystrophies may be detected and studied with
specular reflection.
guttata
USING THE BIOMICROSCOPE TO MEASURE ANGLES
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The biomicroscope can be used to measure rotation, for example
the rotation of soft toric contact lenses.
To measure the rotation of a lens, locate the mark indicating thebase of the prism or horizontal marks on the lens. Using a narrow
parallelepiped, adjust the height of the instrument such that the
center of the beam is approximately in the center of the pupil.
Rotate the beam until it goes through the mark on the lens and the
center of the pupil. The amount of rotation can be read from thescale on the slit-lamp.
lens with mark at base
rotating nasallylens with markings in
horizontal plane rotating
scale on the slit-lamp
showing degrees of
rotation
BIOMCROSCOPY TECHNIQUE
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BIOMCROSCOPY TECHNIQUE
You should practice using the biomicroscope until you are
proficient at using the controls and can do an examination of theanterior surface of the eye in an efficient and smooth manner.