B20M01 8-part Eye Examination.pdf

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8-Part Eye Examination BLOCK 20MODULE 0

Ophthalmologists

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SUMMARY/OUTLINE

I. Distance Acuity Test

II.

External Exam

III.

Pupillary Exam

IV.

Motility Exam

V.

Visual Fields (Confrontation Test)

VI. Tonometry

VII.

Ophthalmoscopy

VIII.

Slit-lamp Biomicroscopy

DISTANCE VISUAL ACUITY

1.

Ask the patient to stand or sit at a designated testing

distance (20 feet)

2. Occlude the left eye (testing one eye at a time)

3. Ask the patient to identify each letter in the chart, on

the lines of successively smaller optotypes, until patient

correctly identifies only half the optotypes on a line

4. Note the corresponding acuity measurement shown at

the line of the chart

5.

Repeat above steps for the left eye, with the right eye

covered

6. Retest acuity with the patients with low vision, e.g.

counting fingers, hand motion, light perception, etc.

Visual acuity can be tested either for distance or near,

conventionally at 20 feet (6 meters) and 14 inches (33 cms)

away, respectively, but distance acuity is the general standard

for comparison. For diagnostic purposes visual acuity is

always tested separately for each eye, whereas binocularvisual acuity is useful for assessing functional vision, such as

for assessing the eligibility to drive.Vaugn Asburys General Ophthalmology 39

thEdition

SNELLENS CHART

Distance visual acuity test should be the first thing to do

during the 8 part eye exam. You should do this before

palpating, or putting any eye medication or drugs so that

visual acuity is not altered because of the prior tests

administered.

In using the snellens chart, place the patient 20 feet away

from the chart.

Remember to test each eye separately and be tested with

and without corrective lenses

But in some clinics, there is only limited space, so they

minimize the distance by converting them to smallerdistances.

The largest letter E is equivalent to 20/200. If the patien

cannot read the letter E, move the patient 5 feet closer

until the patient reaches 5 feet away. Note the distance

where the patient is able to read the letter E. If the patient

still cannot read at 5 feet, proceed to counting finger test.

Some clinics may use meters. Patients usually placed 6

meters away from the chart.

Visual acuity is scored as a fraction (eg, 20/40). The first

number represents the testing distance between the chart

and the patient, and the second number represents thesmallest row of letters that the patients eye can read. Hence

normal vision is 20/20 and 20/60 acuity indicates that the

patients eye can only read from 20 feet letters large enough

for a normal eye to read from 60 feet.Vaugn Asburys General Ophthalmology 39

thEdition

For pediatric patients, you can use figures or the tumbling

E charts

Other patients can use the Jaeger chart. the patient is

scored depending on which line of sentences he can read

J10 is the biggest and J1 is the normal acuity.


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Example result

With

correction

Without

correction

FAR SIGHT

OS 20/150 20/20

OD 20/300 20/20

NEAR SIGHT

OS J8 J1

OD J10 J1

COUNTING FINGERS

By convention, ophthalmologists test first the right eye. If

it is known that the other eye is buron maybe the patient

complained of it before assessment, check the buron eye

first.

In counting fingers, place your finger 1 ft away from the

patient and let the patient count the fingers you are

showing to him. If the patient cannot count at 1 feet away,

move 1 more feet away until you reach the maximum of 3

feet. Record the distance where the patient can count the

fingers shown to him.

After the maximum of 3 feet and the patient cannot count

the fingers, proceed to light perception test.

HAND MOTION TEST

Make sure that you move your hands against the light.

LIGHT PERCEPTION TEST

Make sure to turn off the lights

The patient unable to read the largest (20/200) letter on a

Snellen chart should be moved closer to the chart until that

letter can be read. The distance from the chart is then

recorded as the first number. Visual acuity of 5/200 means

that the patient can identify correctly the largest letter from a

distance of 5 feet but not further away. An eye unable to read

any letters is tested by the ability to count fingers. CF at 2 ft

indicates that the eye was able to count fingers held 2 feet

away but not farther away. If counting fingers is not possible,

the eye may be able to detect a hand moving vertically or

horizontally (HM, or hand motions vision). The next lower

level of vision would be the ability to perceive light (LP, or

light perception). An eye that is totally blindis recorded as

having no light perception (NLP).Vaugn Asburys General Ophthalmology 39

thEdition

EXTERNAL EXAMINATION

1.

Observe the facial skin for any dermal or vascular

changes; note any lesions or evidence of trauma

2. Note any significant asymmetry of facial bones

3. Note the lid position; assess effectiveness of eyelid

closure and strength of the orbicularis muscles if

appropriate

4. Palpate the bony orbit for any lesion or deformity

This is performed before studying the eye under

magnification

Gross inspection and palpation: lesions, growth,

inflammatory signs (swelling, erythema, warmth,

tenderness)

Check for the ff:

o position of eyelids (ptosis, lid retraction)

o asymmetry can be quantified by measuring the

central width (in mm) of palpebral fissure (space bet

lower and upper lid margins)

o abnormal motor fxn of the lids (upper lid elevation,

forceful lid closure) may be due to neurologic o

primary muscular abnormalities

o malposition of the globe (proptosis) that may occur

in orbital disease

o bony orbital rim and periocular soft tissue

General facial evaluation:

o enlarged preauricular LN, sinus tenderness, tempora

artery prominence, skin/mucous membrane

abnormalities

o You canauscultate for bruit at the temporal side of

the orbit or directly at the globe. This can help youdetect carotid sinus fistula

PUPILLARY EXAMINATION

1. Turn off the light to decrease the room illumination

2. Ask the patient to maintain fixation on a distance target

3.

Shine a bright handheld light directly into the right eye

by approaching it from the side or from below

4. Record the direct pupillary response to light in the right

eye in terms of briskness of the response; observe the

consensual reflex by noting the response to light of the

non-illuminated pupil5. Repeat above steps for the left eye

6. Enumerate the steps in performing the swinging flash

light test and explain the clinical significance of relative

afferent papillary defect (Marcus Gunn pupil)

Assessment of pupil function should be done before any

drops are instilled in the eye and before the cornea is

touched (eg, applanation tension or Schirmer test).

Examination of the pupils with a light stimulus provides

evidence of the health of both the afferent and efferent

systems. In addition to light, the pupils also respond to

accommodation and convergence for clear and single vision

at near. The pupils will constrict equally when either

accommodation or convergence is stimulated by a nea

object. When all 3 actionsaccommodation, convergence

and miosisoccur simultaneously, this is called the synkinetic

near response.

Pupil function is evaluated with a bright penlight or other

intense, small light in a dimly illuminated room. Pupil or iris

abnormalities found with the naked eye can then be more

thoroughly evaluated using the biomicroscope. The pupils are


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evaluated for size, shape, direct light response, consensual

response, and near response.

SIZE

In dim illumination, the average pupil diameter is 3 or 4 mm.

This is ascertained by shining the light from below the

patients nose so that the pupils are just visible to the

examiner; the light is not shone directly into the patients

eye. Pupils smaller than 2 mm are said to be miotic; pupilslarger than 6 mm are mydriatic. Miotic pupils may be caused

by antiglaucoma medications, chronic iris inflammation, age,

or a neurologic disorder. Abnormal mydriasis is caused by

certain drugs, neurologic disorders, iris injury, or acute

glaucoma. The pupils should be equal in size, although a

small difference (1 mm) may be a normal variation. I f they are

unequal (anisocoria), the difference between them should be

further evaluated in both dark and bright room illumination.

SHAPE

Both pupils should be round. The pupils are normally

centered or a little nasal in the iris. An eccentric pupil may be

the result of faulty embryonic development, injury,

intraocular surgery, or inflammation. In addition to beingeccentric, a pupil may also have an unusual shape.

DIRECT LIGHT RESPONSE

In dim room illumination, the patient is instructed to look at a

distant target (this prevents the pupillary response to a near

stimulus). The light source is presented to each eye

separately and slightly off center to avoid the near response.

Each pupil should exhibit a brisk response and constrict to

about 2 mm.

CONSENSUAL RESPONSE

The consensual response is the simultaneous and equal

response of one pupil when the other pupil is being

stimulated by direct illumination or a near target. If the

stimulated pupil constricts normally, then the consensual

response of the other pupil will produce equal constriction

without direct light stimulus.

The pupils should be symmetric, and each one should be

examined for size, shape (circular or irregular), and reactivity

to both light and accommodation. Pupillary abnormalities

may be due to (1) neurologic disease, (2) intraocular

inflammation causing either spasm of the pupillary sphincter

or adhesions of the iris to the lens (posterior synechiae), (3)

markedly elevated intraocular pressure causing atony of thepupillary sphincter, (4) prior surgical alteration, (5) the effect

of systemic or eye medications, and (6) benign variations of

normal.

SWINGING PENLIGHT TEST FOR MARCUS GUNN PUPIL

As a light is swung back and forth in front of the two pupils,

one can compare the reactions to stimulation of each eye,

which should be equal. If the neural response to stimulation

of the left eye is impaired, the pupil response in both eyes

will be reduced on stimulation of the left eye compared to

stimulation of the right eye. As the light is swung from the

right to the left eye, both pupils will begin to dilate normally

as the light is moved away from the right eye and then not

constrict or paradoxically widen as the light is shone into the

left eye (since the direct response in the left eye and

the consensual response in the right eye are reduced

compared to the consensual response in the left eye and

direct response in the right eye from stimulation of the righ

eye). When the light is swung back to the right eye, both

pupils will begin to dilate as the light is moved away from the

left eye and then constrict normally as the light is shone into

the right eye. This phenomenon is called a relative afferen

pupillary defect (RAPD).Vaugn Asburys General Ophthalmology 39

thEdition

MOTILITY EXAMINATION

1. Sit facing the patient. Hold finger on or small fixation

target at eye level about 10-14 inches in front of the

patient, with the patient looking straight ahead.

2. Ask the patient to follow the target as you move it into

the six cardinal fields and up and down along the midlineElevate the upper eyelid with a finger on your free to

observe downgaze

3. Note whether the amplitude of eye movement is norma

or abnormal in both eyes

4.

Note any nystagmus that may be present

5. Determine alignment using the Hirschberg method of

corneal light reflection test hold a penlight in front o

the patient eyes at a distance of approximately 2 feet

directing the light at the midpoint between the two eyes

of the patient; instruct the patient to look directly at the

light; compare the position of the two corneal light

reflections and record the estimated result

The extraocular muscles include: the medial, inferior, and

superior recti, the inferior oblique, and levator palpebrae

muscles, all innervated by the oculomotor nerve (III); the

superior oblique muscle, innervated by the trochlear nerve

(IV); and the lateral rectus muscle, innervated by the

abducens nerve (VI).

The precise action of any muscle depends on the orientation

of the eye in the orbit and the influence of the orbita


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connective tissues, which regulates the direction of action

of the extraocular muscles by acting as their functional

mechanical origins (the active pulley hypothesis).

Mnemonic: "SO-4, LR-6, All the rest 3" (ie Superior Oblique by

CN 4, Lateral rectus by CN 6, and all the other EOMs by CN 3).

TESTING OF THE VISUAL FIELD

The patient is asked to follow a target with both eyes as it is

moved in each of the four cardinal directions of gaze. The

examiner notes the speed, smoothness, range, and symmetry

of movements and observes for unsteadiness of fixation (eg,nystagmus). Impairment of eye movements can be due to

neurologic problems (eg, cranial nerve palsy), primary

extraocular muscular weakness (eg, myasthenia gravis), or

mechanical constraints within the orbit limiting rotation of

the globe (eg, orbital floor fracture with entrapment of the

inferior rectus muscle). Deviation of ocular alignment that is

the same amount in all directions of gaze is called comitant.

It is incomitant if the amount of deviation varies with the

direction of gaze.Vaugn Asburys General Ophthalmology 39

thEdition

SIMPLE TEST OF BINOCULAR ALIGNMENT/ HIRSCHBERG

METHOD

Procedure:

1. Have the patient look toward a penlight held several feet

away. (33 cms according to Vaughan & Asburys 18th ed.

Page 244)

2. Note for the pinpoint light reflection, or reflex,.

Note: In normal eyes, pinpoint light reflection, or reflex,

should appear on each cornea and should be centered over

each pupil if the two eyes are straight in their alignment.

If the eye positions are convergent, such that one eye points

inward (esotropia), the light reflex will appear temporal to

the pupil in that eye. If the eyes are divergent, such that one

eye points outward (exotropia), the light reflex will be

located more nasally in that eye.Vaugn Asburys General Ophthalmology 39

thEdition

Landmarks to remember:

0mm Light reflection is at the center of the pupil

1mm Light reflection is in between the center of the pupil

and the pupillary border

2mm Light reflection is at the pupillary border

3mm Light reflection is in between pupillary border and

limbus

4mm Light reflection is at the limbus

KIMPSKY TEST

The Krimsky test is essentially the Hirschberg test, but with

prisms employed to quantitate deviation of ocular

misalignment by determining how much prism is required to

centre the reflex [2] The Krimsky test is advisably used fo

patients with tropias, but not with phorias.https://en.wikipedia.org/wiki/Hirschberg_test

COVER TEST

- More accurate method of verifying normal ocular

alignment.The test requires good vision in both eyes.

Procedure:

1. Ask the patient to gaze at a distant target with both

eyes open. If both eyes are fixating together on the


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target, covering one eye should not affect the

position or continued fixation of the other eye.

2. Suddenly covers one eye and carefully watches to see

that the second eye does not move (indicating that it

was fixating on the same target already). If the

second eye was not identically aligned but was

instead turned abnormally inward or outward, it

could not have been simultaneously fixating on the

target. Thus, it will have to quickly move to find the

target once the previously fixating eye is covered.

Fixation of each eye is tested in turn.

Note!

An abnormal cover test is expected in patients with diplopia.

However, diplopia is not always present in many patients with

long-standing ocular misalignment. When the test is

abnormal, prism lenses of different power can be used to

neutralize the refixation movement of the misaligned eye

(prism cover test). In this way, the amount of eye deviation

can be quantified based on the amount of

prism power needed.

BRUCKNER TEST

The Brckner test is a qualitative assessment of ocula

alignment. This test is done under dark room illumination

and the direct ophthalmoscope aperture set on the largest

aperture setting so as to equally illuminate both eyes. The

examiner is viewing at about 1 meter away and observing the

relative brightness of the fundus reflex from each eye. A

whiter and brighter reflex is noted in the eye that is

strabismic. To confirm a difference in color, retestmonocularly to note any changes to the reflex. The

strabismic eye will appear whiter and brighter as a result of

the fundus reflection emanating from outside of the

pigmented macula region.http://apps.ketchum.edu/ceonline/courseview.a...

VISUAL FIELDS EXAMINATION (CONFRONTATION TEST)

1. Seat the patient and make sure the eye not being testes

is occluded

2. Seat facing the patient at a distance of about 1m. close

your eye that is directly opposite the patients occluded

eye

3.

Ask the patient to fixate on your nose or on your open

eye

4. Hold your hands stationary midway between yoursel

and the patient is opposite quadrants about 30 degrees

from central fixation

5. Quickly extend then retract a finger or fingers on one

hand in one quadrant of the monocular field asking the

patient to state the number of fingers seen

6.

Repeat all four quadrants, testing at least twice per


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quadrant

7. Diagram the confrontation field if an abnormality is

detected

Make sure to test each eye separately. When occluding

the other eye, dont depress the eyeball because it may

cause blurring of vision.

During the 8part eye exam, we are expected to use only

the manual test. Automated perimetry is done in sophisticated diagnostic

centers. Is uses a machine that accurately records the

visual fields. The machine can also determine how much

light the patient can see by altering the intensity of the

light being shown to the visual fields.

It is advisable to make a diagram as to which visual field

is blinded because it can guide you in diagnosis

If the patient has bitemporal hemianopia (number 2)

what possible disease can lead to such problem knowing

that the optic chiasm is the structure affected? Pituitary

tumors.

In automated perimetry:

TONOMETRY

1. Enumerate and differentiate the methods of measuring

intraocular pressure

globe can be thought of as an enclosed compartment

through which there is a constant circulation of aqueous

humor

this fluid maintains the shape and a relatively uniform

pressure within the globe tonometry is the method of measuring intraocular

pressure using calibrated instruments.

normal range is 10 to 21 mm Hg

less corneal indentation is produced as intraocular

pressure rises.

since both methods employ devices that touch the

patients cornea, they require topical anesthetic and

disinfection of the instrument tip prior to use.

with any method of tonometry, care must be taken to

avoid pressing on the globe and artificially increasing its

pressure.

APPLANATION TONOMETRY

- intraocular pressure is determined by the force required to

flatten the cornea by a standard amount. The force required

increases with intraocular pressures.

- the GOLDMANN APPLANATION TONOMETERis attached to

the slitlamp and measures the amount of force required to

flatten the corneal apex by a standard amount.

- the higher the intraocular pressure, the greater the force

required.

- Goldmann applanation tonometer is a more accurate

method than Schiotz tonometry

- following topical anesthesia and instillation of fluorescein

the patient is positioned at the slitlamp and the tonometer isswung into place. To visualize the fluorescein, the cobalt blue

filter is used with the brightest illumination setting. After

grossly aligning the tonometer in front of the cornea, the

examiner looks through the slitlamp ocular just as the tip

contacts the cornea. A manually controlled counterbalanced

spring varies the force applied by the tonometer tip.Upon

contact, the tonometer tip flattens the central cornea and

produces a thin circular outline of fluorescein. A prism in the

tip visually splits this circle into two semicircles that appear

green while viewed through the slitlamp oculars. The

tonometer force is adjusted manually until the two

semicircles just overlap, as shown in Figure 210. This visua

end point indicates that the cornea has been flattened by the

set standard amount. The amount of force required to do this

is translated by the scale into a pressure reading in

millimeters of mercury.


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- accuracy of intraocular pressure measurement is affected by

central corneal thickness. The thinner the cornea, the more

easily it is indented, but the calibration of tonometers

generally assumes a cornea of standard thickness. If the

cornea is relatively thin, the actual intraocular pressure is

higher than the measured value, and if the cornea is relatively

thick, the actual intraocular pressure is lower than the

measured value. Thus ultrasonic measurement of corneal

thickness (pachymetry) may be helpful in assessment of

intraocular pressure. The Pascal dynamic contour tonometer,

a contact but non-applanating technique, measures

intraocular pressure independent of corneal thickness.

- other applanation tonometers are the Perkins tonometer, a

portable mechanical device with a mechanism similar to the

Goldmann tonometer, the Tono-Pen, a portable electronic

applanation tonometer that is reasonably accurate but

requires daily recalibration, and the pneumatotonometer,

which is particularly useful when the cornea has an irregular

surface. The Perkins tonometer and Tono-Pen are commonlyused when examination at the slitlamp is not feasible, for

example, in emergency rooms in cases of orbital trauma with

retrobulbar hemorrhage and in operating rooms during

examinations under anesthesia.

SCHIOTZ TONOMETRY

- now rarely used, measures the amount of corneal

indentation produced by preset weights

- advantage of this method is that it is simple, requiring only a

relatively inexpensive, easily portable hand-held instrument.

It can be used in any clinic or emergency room setting, at the

hospital bedside, or in the operating room, but it requires

greater expertise and has generally been superseded by

applanation tonometers.

NONCONTACT TONOMETRY

- noncontact (air-puff) tonometer is not as accurate as

applanation tonometers.

- small puff of air is blown against the cornea.

- air rebounding from the corneal surface hits a pressure

sensing membrane in the instrument.

- does not require anesthetic drops, since no instrument

touches the eye. Thus, it can be more easily used by

optometrists or technicians and is useful in screening

programs.

OPHTHALMOSCOPY

1.

Position the patient about 2 feet away

2. Turn off the light to dim the room illumination

3. Set the focusing lens of the ophthalmoscope to zero

4.

Check the red reflex from a distance of 2 feet

5.

Approach the patients eye; the instrument is steadied

against the patients face by resting the ulnar border of

the hand holding the instrument against the patients

cheek; the thumb of the free hand raises the upper lid

6.

Instruct the patient to stare into the distance

7. Dial the ophthalmoscopes focusing lenses into place to

clarify the fundus image

8.

Find the optic disc by following a retinal blood vessel

9. Examine the peripapillary retina

10. From the optic disc, follow the blood vessels outward to

examine the four quadrants around the posterior pole

11. Check for foveal reflex

THE DIRECT OPHTHALMOSCOPE

This instrument consists of a single aperture through which

light is projected into the subjects eye and the examiner

views the eye. It provides a magnified image (15) and a field

of view of some 6.510 degrees. A set of corrective lenses can

be dialled into the aperture. These enables the focal point of

the instrument to be adjusted. The rack of lenses usually

contains equal numbers of positive and negative spheres

which can be dialled up to take account of the patient and/or

examiners refractive status. If examiners wish to wear their


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glasses, they can do so, and effectively they will need a zero

lens in the eyepiece. The patients refraction must also be

taken into account and the relevant lens dialed into place.

With highly myopic or hypermetropic patients, their glasses

can be left on and used to nullify the effect of the refractive

variation. Alternatively plus and minus 10 or 20 D lenses can

be positioned in the sight aperture to take account of very

high hypermetropia or myopia. The size and brightness of the

illumination spot can be varied with the appropriate controls.

Additional features vary among the different models but

include a slit filter, producing a vertical slit of light which can

be used to examine contours or elevations on the fundus, a

grid for assessing the size of a fundus lesion, and a green filter

for red-free viewing. This latter filter will make red features,

such as haemorrhages, stand out due to increasing contrast

between the various shades of red and orange which reflect

from the fundus. Some ophthalmoscopes also include a

cobalt blue filter for use with fluorescein dye.

The view obtained with this instrument has a narrow angle of

view and a high magnification. The more myopic the patient,

the more effective the magnifying effect. This is useful forexamining the optic nerve head; however the view is

monocular and two-dimensional.

METHOD OF USE

1. Inform patients that you are going to look at their eye

with a bright light and that you will have to get very close

to their face. Instruct them to breathe normally.

2.

The instrument is held to the examiners eye with the

illumination system switched on and for steadiness and

ease of use a hand can be placed on the patients

shoulder.

3.

The examiners right eye is used for the patients right

eye and the examiners left for the patients left eye. If

the examiner finds it difficult to close one eye, or the

other, then it can be left open with practice the brain

manages to ignore the image from the non-examining

eye.

4. The correct lens, as described above, is dialled into the

aperture.

5.

The patient is asked to fix on a distant object and is told

to maintain that fixation, regardless of whether the

examiner gets in the way. The examiner thus knows

roughly where the patients macula is situated and the

optic disc will be just nasal to this.

6.

The examiner then points the instruments illuminationbeam into the patients pupil and obtains a red reflex

from a distance of about half a metre and slowly moves

towards the patient. At this point media opacities such as

cataract can be seen as black features against the red

reflex. The rheostat is used to adjust the brightness of

the light for the patients comfort. I f required, the front

of the eye, cornea, iris and lens can be examined with a

+10 lens dialed into the instruments lens bank.

7. Following this part of the examination the lens dial is

progressively turned towards zero to focus further back

into the patients eye and eventually reach the retina. It

must be stressed that the head of the ophthalmoscope

must be held very close to the patients eye in order to

gain the maximum field of view.Clinical Skills for the Ophthalmic Examination: Basic Procedures, 2

ndEdition

*For parts of the opthalmoscope: see last page

Macula is usually at temporal side while optic disc is on

the temporal side.

INDIRECT OPHTHALMOSCOPY


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Binocular Indirect Ophthalmoscopy (BIO) is a technique that

provides thorough view of the retina and vitreous through a

dilated pupil in order to evaluate the health of the interior of

the eye and to identify structural abnormalities that may be

associated with reduced visual acuity thereby aiding the

diagnosis of amblyopiaoptometry.osu.edu

Comparison Between Direct and Indirect OphthalmoscopyDIRECT INDIRECT

Magnified image Not magnified

Can see only small area Lets you see bigger area

If with cataract, cannot see Ideal if with cataracts

One handheld apparatus Uses a head gear and a

handheld condensing lenses

SLIT-LAMP BIOMICROSCOPY

1. Identify the different parts of the slit-lamp biomicroscope

2. Enumerate the different uses of the slit-lamp

The slitlamp is a table-mounted binocular microscope with a

special adjustable illumination source attached. A linear slit

beam of incandescent light is projected onto the globe,

illuminating an optical cross section of the eye. The angle of

illumination can be varied along with the width, length, and

intensity of the light beam. The magnification can be adjusted

as well (normally 10 to 16 power). Since the slitlamp is a

binocular microscope, the view is stereoscopic, or three-

dimensional.

Slitlamp photograph of a normal right eye. The curved slit of

light to the right is reflected off of the cornea (C), while the

slit to the left is reflected off of the iris (I). As the latter slit

passes through the pupil, the anterior lens (L) is faintly

illuminated in cross section.

The patient is seated while being examined, and the head is

stabilized by an adjustable chin rest and forehead strap.Vaugn Asburys General Ophthalmology 39

thEdition

Parts of Slit lamp biomicroscopy

Viewing Arm.The binocular eyepieces provide stereoscopic vision and can

be adjusted to accommodate the examiner's interpupillary

distance. The focusing ring can be twisted to suit the

examiner's refractive error.

The magnification element can be adjusted with the side dial.

Illumination Arm

The illumination arm can be swung 180 degrees side to side

on its pivoting bases allowing the examiner to direct the light

beam anywhere between the nasal and temporal aspect o

the eye examination.The dimension of the light beam can be

varied in height and width with these levers. It can provide

diffuse or focal illumination as an optical cross-section of the

anterior segment.Cobalt blue, or green filters can be selected

with this lever.

The Patient Positioning Frame

The patient positioning frame consist of two upright meta

rods to which are attached a forehead strap and a chin rest.


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The chin rest height can be adjusted with the knob just below

it.

The JoystickThe joystick allows for focusing by shifting forward,

backward, laterally or diagonally. The joystick can also be

rotated to lower or elevate the light beam.

The locking screw located at the base secures the slit lamp

from movement when it is not in use.

Just below the slit lamp table on the left is the ON switch and

provides high or low options in light intensity.

Uses of Slit lamp

1. To visualize the anterior half of the globethe

anterior segment.

2.

To study the details of the lid margins and lashes,

the palpebral and bulbar conjunctival surfaces, the

tear film and cornea, the iris, and the aqueous can

be studied.

3.

Through a dilated pupil, the crystalline lens and theanterior vitreous can be examined as well.

4. Because the slit beam of light provides an optica

cross section of the eye, the precise anteroposterior

location of abnormalities can be determined within

each of the clear ocular structures (eg, cornea, lens

vitreous body).

5. The highest magnification setting is sufficient to

show the abnormal presence of cells within the

aqueous, such as red or white blood cells or pigment

granules. Aqueous turbidity, called flare, resulting

from increased protein concentration can be

detected in the presence of intraocular

inflammation. Normal aqueous is optically clear

without cells or flare.Vaugn Asburys General Ophthalmology 39

thEdition

Other uses of slit lamp biomicroscope:- Internet source.

1. Routine observation of ocular adnexia

2. Routine investigation of posterior segment

3. Monitoring signs and symptoms of anterior segment

conditions

4. Further "special eye" investigations

Definition of TermsConjugate movement: Movement of the eyes in the same

direction at the same time.

Deviation: Magnitude of ocular misalignment, usually

measured in prism diopters but sometimes measured in

degrees.

Comitant deviation: Deviation not significantly affected by

which eye is fixing or direction of

gaze, typically a feature of childhood (nonparetic) strabismus.

Incomitant deviation: Deviation varies according to which

eye is fixing and direction of gaze,


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usually a feature of recent onset extraocular muscle paresis

and other types of acquired

strabismus.

Primary deviation: Incomitant deviation measured with the

normal eye fixing).

Secondary deviation: Incomitant deviation measured with

the affected eye fixing.

Ductions: Monocular rotations with no consideration of the

position of the othereye.

Adduction: Inward rotation.

Abduction: Outward rotation.

Supraduction (elevation): Upward rotation.

Infraduction (depression): Downward rotation.

Fusion: Formation of one image from the two images seen

simultaneously by the two eyes.Fusion has two aspects.

Motor fusion: Adjustments made by the brain in innervation

of extraocular muscles in order to

bring both eyes into bifoveal and torsional

alignment.

Sensory fusion: Integration in the visual sensory

areas of the brain of images seen with the twoeyes into one picture.

Heterophoria (phoria): Latent deviation of the eyes held

straight by binocular fusion.

Esophoria: Tendency for one eye to turn inward.

Exophoria: Tendency for one eye to turn outward.

Hyperphoria: Tendency for one eye to deviate upward.

Hypophoria: Tendency for one eye to deviate downward.

(See Hypotropia.)

Heterotropia (tropia):

Strabismus: Manifest deviation of the eyes that cannot be

controlled by binocular vision.

Esotropia: Convergent manifest deviation (crossed eyes).

Exotropia: Divergent manifest deviation (wall eyes).

Hypertropia: Manifest deviation of one eye upward.

Hypotropia: Manifest deviation of one eye upward. By

convention, in the absence of specific

causation to account for the lower position of one eye,

vertical deviations are designated by the

higher eye (eg, right hypertropia, not left hypotropia, when

the right eye is higher).

Incyclotropia: Manifest rotation of the 12 oclock meridian of

one eye about its anteroposterior

axis toward the midline of the head.Excyclotropia: Manifest rotation of the 12 oclock meridian of

one eye about its anteroposterior

axis away from the midline of the head.

Orthophoria: The absence of any tendency of either eye to

deviate when fusion is suspended.

This state is rarely seen clinically. A small phoria is normal.

Prism diopter (PD): The unit of angular measurement used to

characterize ocular deviations. A

1 diopter prism deflects a ray of light toward the base of the

prism by 1 cm at 1 m. One degree of

arc equals approximately 1.7 PD.

Secondary deviation: The deviation measured with the

paretic eye fixing and the

normal eye deviating.

Torsion: Rotation of the eye about its anteroposterior axis

Intorsion (incycloduction): Rotation of the 12 oclock meridian

of the eye toward the midline of

the head.

Extorsion (excycloduction): Rotation of the 12 oclock

meridian of the eye away from the

midline of the head.

Vergences (disjunctive movements): Movement of the two

eyes in opposite directions.

Convergence: The eyes turn inward.

Divergence: The eyes turn outward.

Versions: Binocular rotations of the eyes in qualitatively the

same direction.

B20M01 8-part Eye Examination.pdf

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