Slit Lamp Bimicroscope

Done by : Isa Mushtaha

To: Dr. Hamed AL – Khodari.

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 qualityStereoscopic imageFlexible illuminationFlexible magnification

Therefore there are many different usesEven more when attachments are added

What are the uses of slit lamp

own On their With accessoriesRoutine

examination of anterior segmentAdnexa through

to anterior vitreous

Problem-based examination of anterior segment

GonioscopyFundoscopyOcular

photographyContact

tonometry (Goldmann)

Direct contact goniolenses

• The lamp facilitates an examination of the anterior segment, or frontal structures of the human eye which includes the : 1. Eyelid &eye lashes 2. Cornea3. Sclera4. Conjunctiva5. Iris6. Aqueous7. Natural crystalline lens and 8. Anterior vitreous.

Basic Design1. Viewing arm

Biomicroscope Adjustable focus eyepieces Magnification dial

2. Illumination arm The “slit lamp” Slit size, shape and filter controls Variable size, shape, colour and brightness

3. 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)

4. Moveable base plate and joystick control

Types of illumination incorporated in slit lamp1. Slit width

Wide- survey globe/corneaNarrow- depth, width & position of small

abnormalitiesbeam as wide as cornea is thickforms a parallelepiped volume: a box of illuminated tissue is seen

Thin (slit)- narrowest beam forms an optical section so thin it's just discernible التمييز سهلvaluating small changes in clarity & pinpointing الدقة depth of pathology

2. Light-source intensityMedium to high: most purposes High: optical section

3. Filtersneutral, cobalt blue (for fluorescein),

red-free and red free filter (green filter).4. Magnification

low power (~10x) is used for surveymedium to high (16-40x) for optic

section & parallelepiped Higher than (40x) for specular reflection

normally, light is focused at same point as microscope (“parfocal”)

1. Start with neutralizing the eye piece at zero if the examiner has no refractive error or wearing his glasses & lower powered objective lens .

2. Use lowest voltage setting on transformer

ensure open aperture 3. Select the longest slit length4. Adjust chin rest :

Patient's eyes approximately with level of the marker on head rest .

5. Lamp height of the slit beam centered vertically on Patient's medial canthus

6. Focus by moving joystick

How the examiner can adjust and use the slit lamp

locking nut: loose for free movementOcular focus to 0

adjust beam height for tall, narrow vertical beam

adjust width for narrow beam w/ good illumination

Methods of examination of slit lamp without attachments

There are six basic methods of illumination1. Diffuse illumination 2. Direct focal illumination 3. Indirect illumination 4. Sclerotic scatter 5. Retro-illumination6. Specular reflection

1. Diffuse Illumination : This method is done by using a wide

slit which slightly out of focus and this method is used in examination of the iris and the adnexa of the eye.

The slit should be wide and the magnification should be low as possible to prevent loss of field and enable

large field of view .

2. 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

This method is used to examine the cornea in details , the anterior chamber , crystalline lens , anterior part of the vitreous and in determine if there is flare , pus or blood cells in the anterior chamber .

3. 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) .

This method is used to determine if there is infiltrates رشح , corneal scars , deposits ترسبات and epithelial and stromal defects .

4. 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).

This method is used in examination of scars, foreign bodies, corneal defects and

irregularities in the cornea .

5. Retro-Illumination from the Fundus : This technique is used to observe media clarities

and opacitiesصفاء •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

6. Specular Reflection: it is useful slit lamp technique for scrutinsing the corneal endothelium , the tear film surface , crystalline lens and other surfaces .

A bright reflection will be observed in the anterior surface and less bright reflection will be observed in posterior surface of the cornea .The illumination is narrow parallelepiped and the microscope is placed directly in front of the eye with the light source 25degree from

the microscope . The endothelium will appear clear and rough surface ( due to individual endothelial cells ) .

Attachments of the Slit lamp There are many different attachments and accessories,of these :1. video attachment :used to facilitate

teaching of slit lamp .2. Goldman tonometer :used in measuring

the intra ocular pressure of the anterior chamber .

3. Gold 3-mirror lens : used in measuring the angle of the anterior chamber and center of the retina .

4. Volk double aspheric lens (+60,+78,+90) :used in examination the fundus os the patient indirectly .

5. Direct contact goniolenses : for examination of the periphrey of the fundus .

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