Slit lamp presentation 2015

Amani mohsen

Prepared by:-

Was invented by the Swedish

ophthalmologist and self-

taught mathematician

Allvar Gullstrand (1862-

1930)

The slit lamp:

is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye.

We can use slit lamp as Diagnostic and Treatment

device Because of strong illuminated and highly magnified view of the area

Principle:

A narrow "slit" beam of very bright light produced by lamp. This beam is focused on to the eye which is then viewed under magnification with a microscope

1. Help to detect abnormal in the structures in the front of the eye, such as infection or injury to the cornea, lens, conjunctiva, iris, sclera.

2. Help To detect glaucoma or macular degeneration

3. To check for a foreign body, such as a metal fragment, on or in the eye

4.Detecat intraocular pressure

5.Detect tear film layer

6.Detect the ciliary body, anterior chamber angle structures and funds but when using attachment .

7.Very useful in follow up.

Is controlled by a transformer with adjustable ranges of voltage to provide intense Illumination when required.

The objective of the slit-lamp illumination system is to produce a bright light evenly illuminated ,finely focused ,adjustable slit of light at the eye .

Almost all slit –lamp manufactures have adopted the koller illumination system .

All slit lamps have an illuminating system combined with a microscope, set on an instrument table fitted with a head and chin rest.

This allows both the illuminating system and the microscope to rotate about the point of focus .

This arrangement ensures that light falls on the ( eye’s patient) where microscope is focused.

• The light source L is imaged in the objective O bythe collector system K.

• The objective in turn produces an image at S inthe mechanical slit located next to the collectorsystem .

• The image of the light source at O is the exitpupil.

• The filament is imaged on to the objective lensbut the mechanical slit is imaged on to thepatient’s eye.

- The illumination system isconsists of:

1. A light source : _usually halogen_often with a reflector positioned behind it to maximise illumination.

Zeiss type hag-streit type

2. condensing lenses:

-Usually a pair of aspheric plano-convex lenses.

-These lenses are aspheric to reduce chromaticaberration.

3. projector lens :The diameter of the projection lens is usually fairly small in size.This has two advantage : first is keep the aberrations of the lens down ,which

results in a better quality image . Second it increases the depth of focus of the slit

and thereby produces a better optical section of the eye .

4. a slit aperture or diaphragm to alter length, width and orientation of slit5. Filters.

1- Eyepiece

2- Marked ring for Adjustment of examiner’s refractive error

3- Prism housing

4- Magnification Wheel

5- Objective lens

1.the eyepiece :

With extra pair for higher magnification .

The eye piece has a lens of +10D.

Microscope is binocular .it has 2 eyepieces .

2.Marked ring for Adjustment of examiner’s refractive error :

Enable the examiner to neutralize his or her own

error of refraction .

3.Prism housing :

To overcome the problem of double vision image produced by compound microscope

4. Magnification Wheel :-

Most slit lamp provide a range of magnification from 6x to 40x

5.Objective lens:

In front of patient’s eye to make the working distance about 9-12cm

It presents to the observer an enlarged image of a near object .

1- slit-lamp table (base )

2- head rest and fixation

3- joystick

It concern with :

•Positioning & adjustment of patient and observer

•Maneuvering the illumination and microscope system together with joystick

•Providing base to other parts

A- Power switch :

- The conventional type of slit-lamp only require a transformer for power supply of the low-voltage filament lamp.

- the transformer is fixed underneath the table top.

- the transformer out put for operation on

the main lamp is 5,6 or 7.5 volts and 5 volts for the fixation lamp .

1. slit-lamp table ( base ) :

B -Table height adjustment:

provide the excellent vertically movement of the head rest to provide the best comfort position of

the patient .

C- Lock for slit lamp base :

should lock the base if there is a children around

the instrument .

D- Low friction plate:

to provide an easy movement of

the slit lamp by joystick .

1. slit lamp table ( base ) :

A- Fixation target :

A movable fixation target on top of the head rest to bring the fixation light in front of the examine eye of the patient .

B- black mark

C- Chin rest

D- Hand grip for patient

E- Chin rest adjustment knob

2. head rest and fixation :

- provide the movement of microscope & illumination system vertically ( towards and away from patient's eye ) and horizontally ( from side to side ) .

3. joystick :

1. goldman Tonometer

2. Gonioscopic Lens

3. volk Lens

4. Goldmann 3-Mirror gonioscopic lens :

5. Video attachment

The Goldmann Applanation Tonometer is the most common tonometer that usually mounted on the standard slit- lamp biomicroscope, it use to determine the intraocular pressure of eye. It is an important test in the evaluation of patients at risk from glaucoma.

* Parts :

1.Tonometer tip

2.Metal rod

3.Tonometer housing

4.Force adjustment knob

Contact Non contact

•Different types of Contact and Non-contact lenses used for examination & diagnostic

A-Non-contact lenses

2. volk lenses (+60,+78,+90):

•It have plus power with 2 convex lense , it give a wild field of fundus

•Additional tool for fundus observation with the slit lamp (BIO)

•Mostly indirect; inverted image of the fundus

• Required: •undilated pupil •Coaxial angle (0°) •Illumination - low with 2-4mm slit

•Magnification 10-16 X

B -Contact lenses

· 4. indirect goniolens.

•Additional tool for AC angle observation with the slit lamp

•Mostly direct; inverted image of the angle

•Required :

•dilated pupil •Illumination – low with 2-4 mm slit

•use with liquid to avoid Scratch of cornea & avoid TIR

•Magnification 10 -16 X

◦

•Procedure same as contact fundus lens Observation , it consist of four parts; the central lens and three mirrors set at different angles

•Central lens: Posterior pole • the largest mirror (73°): peripheral of retina (peripheral mirror)

• the intermediate mirror (67° ): Equator of retina (equatorial mirro)

• the smallest mirror (59°) : Iridocorneal angle( Gonioscopy mirror)

Use as teaching tool & to follow up the patient case by taking photo

1.Make the table comfortable for both the examiner and patient.

2.Set magnification on law (6or10).

3.Set IPD comfortable for the examiner.

4.Set up a diffuse beam and medium intensity.

5.Ask the patient to put his head in the forehead rest .

6.Adjust the black marker.

7.Start examine the eye from outside to inside by the method that was explained before.

1-Diffuse illumination

2-Direct focal illumination

3-Indirect illumination

4-Sclerotic scatter

5-Retro illumination

6-specular reflection

This is a good method of observing the eye and adnexa in general

The slit should be opened wide and the magnification should be set as low as possible to enable a large field of view

Wide slit, diffusing inserted, microscope in front, illumination angle 30–50°, magnification of 6-10x

Patients are generally unable to tolerate the brightness of a wide beam

is the most frequently used form of corneal illumination ,focuses the slit beam and microscope at coincident point

the magnification can be increased quite markedly (10x to40x or more)to view any areas of interest in greater detail

A. Wide beam:

2mm slit width enabling corneal surface as well as stroma to be studied .this allows us to test the depth of any interesting feature e.g. foreign body ,corneal abrasion.

A-wide beam B-narrow beamC-conical beam

Use the narrowest slit possible (0.1 – 0.2 mm), this technique is only used if you wish to investigate something the resolution of the section can be improved by reducing the slit width to a minimum and be viewed more clearly by increasing the magnification . generally the angle between the illuminating and observation systems should be set around 45 to 60 degrees ,however to increase the amount of cross section , this angle can be further increased to 90degrees.

tears (outer)

epithelium and bowman s membrane

stroma

endothelium and descemet s membrane

an important modification of direct illumination is used when inflammatory cells within the anterior chamber are suspected

Depends on transmission of light in illumination non transparent tissue

This simply means looking at tissue outside the area which is directly illuminated

This method uses the principle of total internal reflection . A narrow vertical slit (1-1.5mm in width) is directed in line with the temporal or nasal limbus.

a hole of light will be observed around the limbusas light is internally reflected within the cornea , but scattered by the sclera .

any corneal opacities , foreign bodies will be made visible by the scattering light , appearing as bright patches against the dark background of the iris and pupil .

It is important that the room

illumination is as dark as

possible

the light is reflected off the deeper structures , such as the iris and retina , while the microscope is focused to study the more anterior structure in the reflected light like the cornea

the most typical use is to

study the cornea in light

reflected from the iris

or the lens in light reflected

from the retina or choroid

By this method we can see very well both the iris ,the cornea , and the lens

Use the narrowest slit , generally the angle between the illuminating and observation systems should be set 90 degree

relies on the use of the reflective properties of the anterior and posterior corneal surfaces .

The magnification of the microscope must be 200x view through one eye piece

Observe: corneal epithelium

and endothelium,

lens surfaces.

http://vseyeobserver.patternless.com/ophthalmic-equipment/history-of-the-slit-lamp/

http://www.college-optometrists.org/en/college/museyeum/online_exhibitions/optical_instruments/slit_lamps.cfm

http://optometry.berkeley.edu/class/opt260a/labs_pp/labslitlamp.htm

http://www.slideshare.net/dkar2013/slit-lamp-instrumentation-and-illumination-

techniques?qid=f1fd464e-1cec-4381-be7b-098eafb628bc&v=default&b=&from_search=1

Ophthalmic instruments, page (86-92) written by nazik khalaf al-herot

http://www.webmd.com/eye-health/slit-lamp-examination?page=2