Practicum VI
VISUAL ACUITY EXAMINATION
Practical Objectives
After following this practicum, students will be able to identify the subject's visual acuity and check the
refraction (refraction of light) in each eye.
Required tools
Snellens chart
Glasses handle, black opaque cover
Trial lenses in various sizes
Practical Work Procedures
Identifying sharpness:
Visual acuity is checked for each eye separately. One eye is covered with a plate that is mounted on a
glasses handle (montuur, frame). Then sit at a certain distance (d) from the Snellen board.
Check which letters are the smallest that can still be recognized.
Calculate the visual acuity (visus) of that eye. This eye sharpness is expressed by the Snellen Formula:
V=d/D
V=visus = visual acuity
d = distance (in meters) where the eye being examined is located
D = distance (m) at which the eye can still recognize the letters (noted for each type of letter)
Usually the distance d = 6m is chosen because a distance of 6m for the eye is the same as infinite
distance and usually in refraction examinations where accommodation must be eliminated. The d/D
value should not be simplified, so that later from the results we can read how the examination was
carried out.
Refraction:
In this exercise we will check the refraction (refraction of light) of the eye. In the non-accommodating
emmetropic eye, parallel rays converge in the mesh membrane (E). In a non-accommodating
hypermetropic eye, parallel rays converge behind the mesh membrane (H). In an unaccommodated
myopic eye, parallel rays converge at the face of the mesh membrane (M).
Practical Results and Discussion
The minimum viewing angle is the minimum viewing angle at which the eye can still see clearly.
Snellen letters are created based on the eye being able to recognize an object by distinguishing two
points that form a one-minute angle. The reference if you want to make it is with a little note that the
letters are blocked/blackened with the "Courier Bold" typeface.
For the eye, a distance of 6 meters can be equated to infinity because at this distance the rays will be
considered parallel rays which will give an image as if they came from a point located at an infinite
distance in front of the eye, the eye can still see clearly without any accommodation. .
Results of the test person's vision at a distance of 6 meters
Naracoba
Age
VOD
VOS
Conclusion
1
20 years
6/15
6/10
Myopic eyes
If from the experiment you get 6/6 vision, then the person has normal eyes or has normal eyesight
(Emmetrope Eyes), he can see letters at a distance of 6 meters, which is the same as a person with
normal eyes, that the letters can be seen at a distance of 6 meters.
Based on the results of the participant's VOD examination, it was found that he could see objects at a
distance of 6 meters, where people with normal vision could see them at a distance of 15 meters. This
condition is called myopia. Meanwhile, for VOS, the results obtained were that he could see objects at a
distance of 6 meters where people with normal vision saw them at a distance of 10 meters, this
condition is called myopia.
Vision is the sharpness or clarity of vision, a special form which depends on the sharpness of the retinal
focus in the eyeball and the sensitivity of interpretation in the brain. Vision is a quantitative measure of
the ability to identify black symbols on a white background at standardized distances and varying symbol
sizes. It is the most frequently used measure of visual function in the clinic. The term "20/20 vision" is a
number that expresses the distance in feet at which a person can distinguish between a pair of objects.
Another unit in meters is expressed as visus 6/6. Snellen defines “standard vision” as the ability to
recognize one of the optotype objects representing a 5-minute angle. This optotype can only be
recognized if someone looking at it can distinguish some letters/shapes separated by a viewing angle of
1 minute. The optotype is used in examinations at a distance of 6 meters. The largest letter size
representing 6/60 m is 8.8 which, when rounded, becomes 8.9. However, quite a few practitioners
classify the magnitude for these letters as ranging between 8.8-9.0. This describes the distance at which
the lines that form letters can be separated with a visual angle of at least 1 minute, which is read by an
eye without refractive error at a distance of 6 meters.
Visual acuity, tested separately for each eye. One eye is covered with a piece of paper or palm placed
over the eye. Fingers should not be used to cover the eyes (because the client will be able to see
between the fingers). The client is asked to read the letters with each eye separately and the visual
acuity is recorded as a fraction, the numerator being the client's distance from the Snellen chart, and the
denominator being the smallest letter that a normal person can read. When the client is able to read up
to 6 m, visual acuity is recorded as 6/6 (normal).
Twenty feet or at a distance of 6 meters is considered infinity in optical perspective (the difference in
optical power required to focus a distance of 20 feet to infinity is only 0.164 diopters). For this reason,
20/20 vision can be considered nominal performance for human distance vision, 20/40 vision can be
considered half the distance vision and 20/10 vision is twice the normal vision. Abnormalities/disorders
that can occur in the eyes during this experiment are:
Nearsightedness (Myopia)
Myopia is an eye disorder that prevents you from seeing objects that are far away. This is because the
eye lens is too thick, so the image falls in front of the retina. Myopia can be helped with concave lens
glasses.
Nearsightedness (Hyperopia)
Hypermetropia is an eye disorder so that sufferers cannot see objects that are close up clearly. This is
because the lens of the eye is too flat so that the image of objects falls behind the retina.
Nearsightedness can be helped by using glasses with convex lenses.
Conclusion
It can be concluded from the results of this practicum that visual acuity (visus) examination can be
carried out using a Snellen chart which is made based on the eye being able to recognize an object by
distinguishing two points that form a one minute angle. Visual acuity is checked one by one, for example
the right eye (OD) first, then the left eye (OS) and expressed by a numerator/denominator, the
numerator is the distance between the Snellen optotype and the eye.
Practicum VII
HEARING ACUITY EXAMINATION: RINNE, WEBER, AND SCHWABACH TEST
Practical Objectives
After following this practicum students will be able to:
Carry out hearing function checks by:
a. Rinne
b. Webber
c. Schwabach
State the purpose of the inspection above (number 1)
Summarize the results of the examination above
Required tools
Tuning fork
Cotton to plug the ears
Practical Work Procedures
Rinne's way
The tuner vibrates (frequency 256) by hitting one of the fingertips against the palm of the hand. Never
hit a hard object.
Press the tip of the tuning rod on the mastoid process of one of the experimenter's ears.
Ask the experimenter if he or she hears a buzzing sound in the ear being examined, if so the
experimenter should immediately give a signal when the buzzing sound disappears. With what type of
conduction does one hear a buzzing sound in action number 3?
At that moment the examiner lifts the tuner from the proc. The test person's mastoid then brings the tip
of the tuning finger as close as possible to the front of the ear canal being examined. With what type of
conduction does one hear a buzzing sound in action number 4?
Record the results of Rinne's examination as follows:
Positive: if the test person still hears the buzzing in aerotympanal conduction.
Negative: if the test person no longer hears the buzzing in the aerotympanal conduction.
Webber Way
Vibrate the tuner (Frequency 256.) in the manner as in number 1. A
Press the tip of the tuning rod on the test person's forehead at the median line
Ask the experimenter whether he hears the buzzing of the tuner equally strongly in both ears or
whether lateralization occurs. What is meant by lateralization?
If the experimental person does not experience lateralization, then to artificially cause lateralization,
cover one ear with cotton and repeat the examination. Explain the mechanism of lateralization.
Schwabach's Way
Vibrate the tuner (Frequency 256.) in the manner as in number 1.a
Press the tip of the tuning rod on the proc. Mastoideus was one of the experimenters.
Have the experimenter raise his hand when the buzzing sound disappears.
At that time the examiner immediately removes the tuner from the proc. Mastoideus experimental
person proc. The mastoid itself. In this examination, the examinee's ears are considered normal. If the
buzzer of the tuner after being declared stopped by the experimenter can still be heard by the examiner
then the result of the examination is SHORT SCHWABACH.
If the buzzer of the tuner after being declared stopped by the experimenter cannot be heard by the
examiner then the examination result may be NORMAL SCHWABACH.nPROLONGED SCHWABACH. To
ensure this, the following checks are carried out:
The tuner is vibrated, the tip of the tuning rod is first pressed into the examiner's mastoid process until it
can no longer be heard, then the tip of the tuning rod is immediately pressed into the mastoid process
of the test person. If the buzzing (after being declared to have stopped by the examiner) can still be
heard by the experimenter then the result of this examination is a PROLONGED SCHWABACH. If the
buzzing after being declared to have stopped by the examiner cannot be heard by the test person, then
the examination result is SCHWABACH NORMAL.
What is the purpose of a hearing test with a tuner in the clinic? And what is the interpretation of each
examination?
Practical Results and Discussion
Experimental Person
Rinne
Webber
Schwabach
Conclusion
Naomi Sella A.
+
+
Same
Same
Normal
Alvira Putri G.
+
+
Right
-
Normal
Luciana Tasya
+
+
Same
Same
Normal
A positive Rinne means that the test person still hears aerotympanal buzzing sounds
Rinne negative means that the test person cannot hear the hum through the aerotympanal conduction
Weber lateralizes to the left meaning he cannot hear the ringing in the left ear but can still hear the
buzzing in the right ear
Schwabach bone conduction of the experimenter is prolonged, meaning that the buzzing after being
declared stopped by the examiner can still be heard by the experimenter.
Sound or voice is a series of waves that propagate from a vibration source as a result of changes in
molecular density and air pressure. The closer the sound source, the louder the sound is heard. Sound
energy gradually weakens as the sound wave travels away from its source and the sound energy will
eventually dissipate when the sound wave is too weak to disturb the surrounding air molecules. The
sensitivity of the ear is influenced by intensity or strength where the intensity of sound strength
depends on the amplitude of the sound wave or the pressure difference between the high pressure
compaction area and the low pressure stretch area. The human ear can hear a wide range of sound
intensities, from the faintest whisper to the loudest sound.
Sound strength is measured in decibels (dB), which is a logarithmic measure of intensity compared to
the faintest sound that can still be heard (hearing threshold). The ticking of the clock as heard by the
two participants usually has a relative strength of 20 dB, which is 100 times stronger than the hearing
threshold. Everyone's hearing threshold is different. Every normal person is able to hear sounds with a
frequency of 20-2000 Hz with a power of 100 dB. Sounds greater than 100dB can permanently damage
the sensitive sensory devices in the cochlea.
In this practicum, several experiments were carried out to check the deafness of the participants. The
experiments carried out were the Rinne experiment, the Weber experiment, and the Schwabach
experiment. The four experiments are intended to find out whether a person's hearing is still good by
examining sound conduction, both air conduction (AC) and bone conduction (BC), so that we can
determine whether there is hearing loss or not.
Rinne test, a vibrating tuning fork handle is placed behind the auricle on the mastoid bone (bone
conduction) until the patient can no longer hear sounds. The mastoid process is the part of the temporal
bone located behind the ear. The Rinne test is a hearing test carried out to evaluate hearing ability in
one ear (unilateral deafness). In this way, a condition of conduction deafness can be quickly assessed.
The results of the three experimenters showed that they could hear from 2 types of transmission,
namely aerotympanal conduction and bone conduction in both ears. So they do not experience
conductive or sensorineural abnormalities.
In the Webber test, one of the experimenters experienced right literacy, namely when he heard a louder
buzz or vibration on the right side. This assessment using the Weber test aims to assess bone conduction
by examining sound lateralization (transmission from the side). The practical results showed that some
of the participants heard louder on the right side, this explains that the patient's bone conduction was
abnormal because there were parts that sounded louder. In principle, this experiment was carried out to
compare the bone conduction of the patient's left and right ear. It is said to be normal if the sound
sounds equally loud on the left and right, then the hearing condition of the person in the second
experiment is said to be abnormal.
The Schwabach test compares the BC conductance of the patient's bones with that of the examiner,
provided that the examiner's BC is normal. The results obtained when the experimental person no
longer hears the sound and the examiner no longer hears the sound, then the results show that the
experimental person's BC is the same as the examiner's BC. Because the test person's BC in the
experiment is the same as the examiner's BC, it can be said that the patient's hearing is normal.
However, there are several factors that cause the hearing test to be ineffective which will change the OP
test results, namely:
Surrounding environment, this factor is very important to pay attention to during a hearing examination.
If the environment around the examination site is busy, it will interfere with the OP's concentration in
carrying out the experiment which will result in incorrect data because what he actually heard does not
match the results that should be. So, to be more effective, it is recommended to carry out a hearing test
in a more closed place and away from noise so that the results of the examination are truly in
accordance with the original.
Age, this factor could influence the results of the experiments carried out because as we know, usually
the elderly are no longer sharp in terms of hearing, therefore. Perhaps most elderly people who have
had their hearing checked will experience some hearing problems due to their age.
Using a tuning fork, if the tuning fork used for experiments from OP 1 to OP 2 and then OP 3 is changed
intentionally or unintentionally then the impact will result in data errors in the OP data, because the
purpose of the tuning fork is to transmit vibrations and sounds, so if Different tuning forks used will
change the results too.
Damage to the mastoid process bone, this event results in the conduction of vibrations that should
reach the brain instead of reaching the brain due to damage to the mastoid process, so that the ear feels
that it cannot hear or feel the vibrations coming from the tuning fork so that the OP data becomes
wrong, and that's the end of it for the examiner. to misinterpret the conclusion because the data alone
is wrong.
Conclusion
From the examination of voice acuity and type of deafness carried out, several things can be concluded
as follows.
In the Rinne test, the acuity of the three participants was still classified as normal
Each person's sound sensitivity is different but is generally influenced by the frequency and
intensity/strength of the sounds around them.
The second time when doing the Webber test, the result was that he experienced correct literacy
The Schwabah test examination of all the participants showed the same results as the examiner
Not all experimental results are true, they can also be influenced by the things explained above, so
before carrying out a sound acuity check, you need a place that is soundproof or far from air noise
because it will affect the final results so that the results are not effective.
Practicum VIII
BALANCE TEST
Practical Objectives
After participating in this practicum students will be able to:
Demonstrate the importance of head and eye position in maintaining body balance in humans
Demonstrate and explain the effect of angular acceleration
With a swivel chair against:
Eye movement (nystagmus)
Appointment deviation test
Drop test
Sensation
By walking around the stick
Required tools
Swivel chair
A long stick or cane
Tub filled with water
Practical Work Procedures
The effect of normal head and eye position on body balance:
Have the experimenter walk along a straight line on the floor with his eyes open and his head and body
in a normal posture. Pay attention to his path and ask him if he is having difficulty following the straight
line.
Repeat the experiment above (no. 1) with your eyes closed.
Repeat the experiment above (no. 1 and 2) with
The head is tilted strongly to the left
The head is tilted strongly to the right
How does the attitude of the head and eyes affect body balance?
Experiment with a swivel chair
Nystagmus:
Have the experimenter sit upright in a swivel chair with his hands firmly gripping the arms of the chair
Cover his eyes with a handkerchief and bend his head 30º forward
Turn the chair to the right 10 times in 20 seconds regularly and without jerking
Stop turning the chair suddenly
Open the handkerchief and ask the experimenter to look far ahead
Note the presence of nystagmus
What is meant by rotatory nystagmus and postrotatory nystagmus?
Designation deviation test
Have the experimenter sit upright in a swivel chair and cover his eyes with a handkerchief
The examiner stands directly in front of the swivel chair while extending his left hand towards the
experimenter
Have the experimenter extend his right arm forward so that it can touch the examiner's previously
extended finger
Have the experimenter raise his right arm up then quickly lower it again so that it can touch the
examiner's finger again
Now have the experimenter, with both hands firmly holding the arms of the chair, bend his head 30º
forward
Turn the chair to the right 10 times in 20 seconds regularly without jerking
Immediately after screening, the chair is stopped suddenly, have the experimenter hold his head upright
and perform the pointing deviation test as above.
Pay attention to whether there is any deviation in the appointment by the experimenter. If a deviation
occurs, determine the direction of the deviation. Continue the test until the test person can
unmistakably touch the examiner's finger
Actions No. 1 to No. 4 are preparations for the actual test as follows
How does past pointing occur?
Drop Test
Have the experimenter sit in a swivel chair with both hands firmly holding the arms of the chair
Cover both eyes with a handkerchief and bend the head and body so that the head forms an angle of
120º from the normal position
Turn the chair to the right 10 times in 10 seconds regularly without jerking
As soon as the rotation of the chair stops suddenly, have the experimenter straighten his head and body
back up
Watch where he falls and ask the experimenter where he feels like he will fall
Repeat this fall test, each time on another test person with: a. Tilt your head towards your right shoulder
so that your head is tilted 90º to the normal position
Tilt your head back so that it makes a 60º angle
Correlate the direction of fall in each trial with the direction of endoline flow in the stimulated
semicircular canals
Impression (sensation)
Use another test person
Have the experimenter sit on a rotating chair and cover his eyes with a handkerchief
Turn the chair to the right with a gradually increasing speed and then gradually reduce the rotation
speed until it stops
Ask the test person the direction the feeling is turning when
While the rotation speed is still increasing
When the rotational speed remains constant
When the rotation speed is reduced
As soon as the chair is stopped.
Give information about the mechanism for the direction of the spinning feeling felt by the experimental
person
Simple experiment for horizontal semicircular canals
Have the experimenter with his eyes closed and head bowed 30º turn while holding on to a stick or
stand, clockwise, 10X in 30 seconds
Have the experimenter stop, then open his eyes and walk straight ahead
Watch what happens
Repeat this experiment by rotating in a counterclockwise direction
What would you expect to happen to the test person when walking straight forward after turning 10X
clockwise?
Practical Results and Discussion
The influence of normal head and eye position on body balance
The effect of normal head and eye position on body balance:
Experimental person's path: Straight
Difficulty passing in following a straight line: No difficulty
If there are difficulties, this situation is caused by: -
The effect of head position and closed eyes on body balance:
People trying their way: There are difficulties
Difficulty passing in following a straight line: There is difficulty
If there is difficulty, this situation is caused by: the experimental person experiences difficulty and is a
little confused because in the balance system three components play a role, namely vision, the
propoiseceptor organ and the organ of balance (vestibular), whereas in the experimental person their
vision is closed so their balance is slightly disturbed.
The effect of normal head and eye position with the head tilted to the left on body balance:
Experimental person's path: Straight
Difficulty passing in following a straight line: No difficulty
If there are difficulties, this situation is caused by: -
The effect of normal head and eye position with the head tilted to the right on body balance:
People trying their way: There are difficulties
Difficulty passing in following a straight line: Yes
If there is difficulty, this situation is caused by: Incorrect head position
The effect of head position and eyes closed with the head tilted to the left on body balance:
People trying to walk: Tilting, almost falling
Difficulty passing in following a straight line: Yes, not straight
If there is difficulty, this situation is caused by: Closed eyes cannot determine the baseline point (normal
corner point)
The effect of head position and closed eyes with the head tilted to the right on body balance:
People who try their way: Unbalanced
Difficulty passing in following a straight line: Not straight
If there is difficulty, this situation is caused by: Closed eyes cannot determine the baseline point (normal
corner point)
Experiment with a swivel chair
The position of the eyes in the experimental person is:
Rotatory nystagmus is a forced rotation of the eyes about the visual axis
Postrotatory nystagmus is a normal finding after rotation, with a rapid phase away from the direction of
rotation
In the appointment test, the probationer performs:
The experimenter tries to touch the hand of the person in front of him, but the experimenter's hand
tends to be pulled to the right so he points incorrectly (fails to touch the pointer's hand).
The experimenter had no errors in pointing after 2 minutes
Past pointing occurs because the rotation process causes changes in the vestibular system and also
affects the experimenter's vision and body movements so that the experimenter's balance is temporarily
disturbed.
Drop Test
Experiment I fell to the right
Test person I felt he was going to fall to the right
The relationship between the direction of fall in experimenter I and the direction of endolymph flow in
the stimulated semi-circular canals is in the opposite direction due to compensation. As a result, if the
rotation is stopped and the head is straightened, the flow of endolymph will bend the cupula in the
direction of rotation so that OP feels as if there is a gap on his right side. As a result, the body will fall to
the left side to balance this
Experiment II person fell to the left
Experiment II person felt he was going to fall to the right
The relationship between the direction of fall in experiment II and the direction of endolymph flow in
the stimulated semi-circular canals is in the opposite direction due to compensation.
Test person III fell backwards
Experimenter III felt like he was going to fall backwards
The relationship between the direction of fall in experimenter III and the direction of endolinfe flow in
the stimulated semi-circular canals is in the opposite direction due to compensation.
Impression (sensation)
While the rotational speed was still increasing, the experimenter felt that he was rotating to the right
When the rotational speed remains constant, the experimenter feels that he is rotating to the right
When the rotational speed is reduced, the mass experimenter rotates to the right
As soon as the chair was stopped, the experimenter felt it rotate to the left
The mechanism for the direction of the feeling of rotation that is felt when the rotation speed is
constant, the participant cannot feel the direction of rotation, and when the rotation speed is reduced,
the participant feels rotated to the left and when the chair is rotated, it is stopped, the participant still
feels rotated to the left
Simple experiment for horizontal semicircular canals
When the participant is turned to the right → they feel like falling to the left
When the participant is turned to the left → they feel like falling to the right
In the balance system, three components play a role, namely vision, propoiseceptor organs (muscle
sense) and balance organs (vestibular/inner ear). The function of the eyes (vision) conveys messages to
the brain that the body is standing upright or tilted. Messages by the eyes and muscles are combined by
the brain with a third message from the semicircular canals of the inner ear. If these three systems are
in normal condition then the process will be well balanced. However, if there are two organs whose
balance components are not normal then the process cannot be balanced.
When the eyes were opened in various head positions, the test person was able to walk perfectly
straight and had no difficulty following a straight line. This means there are no problems when the
superior semicircular canal is repositioned and with normal eyes. Because there are still at least two
balance components that function normally. When conducting a nystagmus experiment (after the
experimenter is turned to the right 10 times in 20 seconds), the experimenter's eyes tend to move
quickly to the left and slow to the right due to the presence of the vestibulo-ocular reflex (VOR) which is
a reflex eye movement to stabilize image on the retina during head rotation.
During the test, irregularities in the screening process cause changes in the vestibular system and also
affect the test person's vision and body movements so that the test person's balance is temporarily
disturbed. Meanwhile, in the fall test, when the rotation is stopped and the head is straightened, the
flow of endolymph will bend the cupula in the direction of rotation so that the test person feels as if
there is a cliff on his right side. The direction of the fall of the experimental person's body is opposite to
the direction of rotation of the endolymph in the semicircular canals which is the axis of rotation. This is
a form of compensation mechanism and connection between the vestibular and proprioceptor systems.
In the impression (sensation) experiment, what happens is that when the test person is rotated for the
first time, the endolymph flow will flow in the opposite direction to the direction of rotation, the cupula
will move in the same direction as the endolymph flow, then when the rotation speed remains constant
(constant), no acceleration will be produced , so that the cupola returns to its normal position but it still
takes some time to return to the initial position. When the rotation speed is reduced (deceleration), the
endolymph fluid will flow in the direction of rotation, as well as the direction of movement of the
cupula.
Conclusion
Head position and rotation will stimulate the semicircular canals.
The eyes and head position affect a person's balance.
The fast component of postrotational nystagmus is opposite to the direction of rotation while the slow
component is in the direction of rotation
The direction of post-rotation pointing will deviate in the direction of the rotation performed.
The flow of endolymph will influence the impression of the direction of rotation that occurs.
The semicircular canals detect angular or rotational acceleration or deceleration of the head.
