SAMPLE TEST

Question 1

Which of the following medications may affect successful contact lens wear ?

Answer 1

Antihistamines are beneficial when treating allergies and cold symptoms because they dry
out the mucous membranes of the nasal passage. However, this may also lead to dehydration
of the tear film. Antihistamines have also been known to slow down the blink rate and
increase corneal sensitivity.

Question 2

What is the term for light sensitivity ?

Answer 2

Photophobia refers to a sensitivity (“phobia”) to light (“photo”). Presbyopia is the condition
that results when patients are no longer able to focus on objects at a near point.
Pannus is the invasion of blood vessels onto the cornea. Ptosis is a drooping of the upper
eyelid.

Question 3

The following is an example of what kind of astigmatism ?K’s 42.50 @ 180/40.50 @ 90

Answer 3

Against-the-rule-astigmatism is present when the keratometer readings are steeper in the
horizontal meridian (42.50 @ 180) than in the vertical meridian (40.50 @ 90).

Question 4

The cornea receives nutrients from what ?

Answer 4

The normal cornea is devoid of blood vessels. To provide metabolites, the cornea is
nourished by diffusion of nutrients and oxygen by the aqueous humor, tears and vascular
blood vessels in the limbus. The orbicularis occuli is a muscle in the eyelid whose primary .
function is lid closure.

Question 5

Increased loss of ability of the lens to accommodate is called ?

Answer 5

Presbyopia is the gradual loss of accommodation due to the hardening of the crystalline
lens that takes place as a person ages

Question 6

Increased loss of ability of the lens to accommodate is called ?

Answer 6

Presbyopia is the gradual loss of accommodation due to the hardening of the crystalline
lens that takes place as a person ages.

Question 7

Which Instrument can provide stimulation information about the cornea, lids, conjunctiva, lashes, contact lens surface and fit ?

Answer 7

Slit lamp
The radiuscope will measure the base curve of a rigid contact lens. The corneascope and
keratometer will give important information about the surface of the cornea. Only the slit
lamp (or biomicroscope) can provide simultaneous information about the cornea, lids,
conjunctiva, lashes, contact lens surface and fit.

Question 8

What are the layers of the tear film ?

Answer 8

Lipid, aqueous, mucin

Question 9

Transpose Rx -4.50 +1.25 x 94

Answer 9

To transpose a prescription from plus to minus cylinder, first add the amount of cylinder
to the sphere power: -4.50 + (+1.25) = -3.25
Then change the sign of the cylinder power from plus to minus: +1.25becomes -1.25
Finally, add or subtract 90 degrees from the cylinder axis: 94 - 90 = 4

Question 10

Avg pH Value of Tears

Answer 10

Values higher than 7.4 are considered relatively alkaline, whereas values lower than 7.4
are considered relatively acidic.

Question 11

If the manufacturer’s guidelines suggest

a minimum of 4 hours for disinfection,what would you suggest to the patient?

Answer 11

Patients should always be directed to follow the manufacturer’s guidelines and not try to
cut corners by leaving lenses in any solution for less than the recommended time. While
overnight is longer than recommended and would not pose a problem for most: patients,
they should always be given very specific guidelines for time.

Question 12

What is the term for the condition in
which there is loss of vision without any
apparent disease to the eye?

Answer 12

Patients are amblyopic when they are not able to attain 20/20 vision with an eye that has
not experienced any disease or trauma. Aniridia is the absence of an iris. Astigmatism
refers to a refractive error in which light rays do not focus in a single point. Ap hakia is the
absence of the crystalline lens.

Question 13

Which auxiliary trial lens will extend the
keratometer range to approximately
30.00 D?

Answer 13

By placing a -1.00 D lens over the aperture of the keratometer, you can extend the low end
range from 36.00 D to 30.00 D.

Question 14

Which step should be performed first
when taking keratometer measurements?
A. Rotate the drum to reflect the
cylinder axis
B. Adjust the patient so that they are
comfortable
C. Focus the eyepiece
D. Cover the patient's eye that is not
being measured

Answer 14

The answer is C
Before the patient is seated in the keratometer, the examiner should focus the eyepiece.
This is particularly important if you are not the only person using the keratome ter during
the day.

Question 15

The following is an example of what type
of astigmatism?
K’s 44.00 @ 180/44.50 @ 90
Rx -3.00 -2.50 x 180

Answer 15

Lenticular astigmatism is present when there is significantly more astigmatism in the
patient’s refraction (2.50 D) than on their corneal surface (0.50 D). In this case, the
astigmatism is not represented on the cornea and is most likely found in the crystalline
lens.

Question 16

Ocular signs of aging include:

1) Tear film abnormalities
2) Reduced lid elasticity
3) Lens opacities
4) Loss of accommodation

Answer 16

ALL of them

Question 17

Transpose the following Rx into minus
cylinder form: Rx +1.50 +1.00 x 75
A. +1.50 -1.00 x 75
B. +2.50 -1.00 x 75
C. +2.50 -1.00 x 165
D. +2.50 -1.00 x 175

Answer 17

The answer is C
To transpose a prescription from plus to minus cylinder, first add the amount of cylinder
to the sphere power: + 1.50 + (+1.00) = +2.50
Then change the sign of the cylinder power from plus to minus: +1.00 becomes -1.00
Finally, add or subtract 90 degrees from the cylinder axis: 75 + 90 = 165

Question 18

The pre-corneal tear film provides:

1) A smooth optical surface
2) Metabolic nutrients to the epithelium
3) Oxygen to the endothelium
4) Limbal hyperemia

Answer 18

The pre-corneal tear film provides a smooth optical surface for the cornea. This is maintained
by the blink mechanism, further providing metabolites (e.g., oxygen) to and from the cornea as well as removing waste products such as CO2 and dead epithelial cells. The
endothelium receives its oxygen from aqueous humor within the anterior chamber. Limbal
hyperemia is redness from engorged blood vessels in the limbal area.

Question 19

The cornea has five distinct layers. In
order from anterior (front) to posterior
(back) they are:

Answer 19

Epithelium, Bowman’s layer, Stroma,

Descemet’s membrane, Endothelium

Question 20

The normal cornea is transparent due to
the pump action creating proper fluid
balance. Which layer of the cornea is
most responsible for maintaining this
function?

Answer 20

The corneal endothelium provides the pumping mechanism of the cornea to expel fluid
from the tissue and maintain corneal transparency. Bowman’s layer is an acellular layer
which provides strength to the cornea. The epithelium is the outermost layer of the cornea
and only plays a minor role in corneal metabolism. The basal membrane is a basement
membrane which provides an attachment surface for the epithelium to adhere to
Bowman’s layer.

Question 21

A normal tear break-up time is:

Answer 21

Typically fluorescein will remain on the cornea for 10-12 seconds before it begins to break
up and dry spots appear. Less than seven seconds is considered a short break-up time and
may limit the success of contact lens fitting.

Question 22

A whitish haze in the peripheral corneal
stroma which does not stain and is often
seen in the elderly is known as:
A. Neovascularization
B. Dellen
C. Arcus Senilus
D. Fuch's Dystrophy

Answer 22

Arcus senilus consists of cholesterol deposits in the corneal periphery and does not affect
contact lens wearing. A dellen is a depressed area of compromised epithelial tissue on the
cornea which stains due to lack of wetting from the pre-corneal tear film. It is generally
found adjacent to an elevated area. Neovascularization is the abnormal growth of new
blood vessels into the cornea. Fuch’s dystrophy is a corneal endothelial dystrophy affecting
the central cornea.

Question 23

Patients with keratitis sicca are more
prone to:
A. Secondary infections
B. Loss of eyelashes
C. Losing their contact lenses
D. Steepening corneas

Answer 23

Keratitis sicca is a severe dryness of the cornea. This leaves the cornea at risk, exposing it
to complications related to secondary infections. Loss of eyelashes or contact lenses and
steep corneas are not related to keratitis sicca.

Question 24

Upon removal of the crystalline lens, the
patient is:
A. Aphakic
B. Myopic
C. Hyperopic
D. Astigmatic

Answer 24

Aphakia is the absence of the crystalline lens.

Question 25

The following Rx represents:
OD +2.00 = 20/20
OS -3.00 -2.00 x 180 = 20/20
A. Presbyopia
B. Anisometropia
C. Amblyopia
D. Emmetropia

Answer 25

Anisometropia is present when the refractive errors of a patient’s two eyes are so different
from one another that retinal images of disparate sizes result. Because of the different
sizes, fusion of the two images may not occur.

Question 26

The following Rx represents:
OD +2.00 = 20/20
OS -3.00 -2.00 x 180 = 20/20
A. Presbyopia
B. Anisometropia
C. Amblyopia
D. Emmetropia

Answer 26

Anisometropia is present when the refractive errors of a patient’s two eyes are so different
from one another that retinal images of disparate sizes result. Because of the different
sizes, fusion of the two images may not occur.

Question 27

OD +2.00 = 20/20
OS -3.00 -2.00 x 180 = 20/20
is Anisometropia
best achieve stereopsis with which of
the following modalities?
A. Contact lenses
B. Spectacles
C. IOL
D. Bifocals

Answer 27

The answer is A
A patient’s depth perception (stereopsis) will be compromised if fitted with spectacles. An
IOL (intraocular lens) is used for aphakia.

Question 28

Tom's spectacles with a power of -12.00
\+0.50 x 90, sit 10mm in front of his
cornea. The likely soft contact lens
prescription for Tom would be:
A. -10.50 D
B. -11.75 D
C. -12.00 D
D. -12.50 D

Answer 28

The answer is A
The vertex distance correction is usually derived from a standard table. ill the conversion of a
prescription from the spectacle plane to the corneal plane, additional plus power is needed.

Question 29

The keratometer is an instrument used
to measure:
A. Corneal curvature
B. Lens power
C. Lens diameter
D. Lens thickness

Answer 29

The answer is A
A lensometer measures power. A diameter gauge measures diameter. A thickness gauge
measures thickness.

Question 30

The average life span of a corneal
epithelial cell from mitosis through
maturation and desquamation most
nearly approximates:
A. One day
B. One week
C. One month
D. One year

Answer 30

The answer is B

A typical cycle may range from four to ten days.

Question 31

Which auxiliary trial lens will extend the
keratometer range to approximately
61.00 D?
A. -1.25D
B. +1.25D
C. -1.50 D
D. +1.50D

Answer 31

The range of the keratometer is 36.00 D to 52.00 D. To extend the range above 52.00 D,a
+1.25 D lens is used.

Question 32

Wearing lenses in high altitudes and dry
environments may result in complaints
of all but the following:
A. Photophobia
B. Chalazion
C. Grittiness
D. Burning sensation

Answer 32

The answer is B
Photophobia, burning sensations and feelings of grittiness can all be attributed to dry, low
oxygen environments. A chalazion is an inflammation of a meibomian gland and is not
related to dryness.

Question 33

The first line of defense in the protective
system of the eye is formed by the:
A. Sebaceous glands
B. Lacrimal glands
C. Eyelids
D. Caruncle and semilunar folds

Answer 33

The answer is C
The eyelids remove debris as we blink, control the amount of light that enters the eye and (
distribute tears across the cornea and conjunctiva to keep those tissues from drying out.

Question 34

Transient Keratomertic mire distortion is usually due to ?

Answer 34

The answer Pre-ocular tear film
While prolonged rigid lens wear, prolonged soft lens wear and irregular corneal astigmatism
may all cause mire distortion, the mire distortion will remain constant. Of the choices
listed, only the tear film results in transitory mire distortion which can be cleared up if you
ask the patient to blink.

Question 35

In against the rule astigmatism the steepest corneal median is

Answer 35

Is at or near 180 degrees
In against-the-rule astigmatism, the cornea has a vertical ellipsoidal shape. This puts the
long, flat meridian at 90 degrees and the short, steep meridian at 180 degrees.

Question 36

In ability to bring all the keratometer mires into focus at the same time may indicate

Answer 36

The answer is C
In cases of irregular astigmatism the major meridians are not 90 degrees apart causing the
mires to not focus all at the same time. The meridians are 90 degrees apart when measuring
with-the-rule, against-the-rule and oblique astigmatism.

Question 37

In an alignment lid attachment GP Fit. The Fluorescein patter should show ?

Answer 37

A thin even layer of fluorescein and less than 180 degrees of bearing in the mid periphery.

Lid attachment GP fits should show a thin, even edge-to-edge layer of fluorescein stained
tear film that exhibit alignment or slight apical feathering as well as less than 180 degrees
of bearing in the mid-periphery to allow for a good tear exchange with each blink. Choice
A, apical clearance with 360 degrees of bearing in the mid-periphery indicates a steep,
tight fit with complete seal-off and no tear exchange. Choices C and D are indicative of an
excessively flat fit.

Question 38

In a GP wearer an arcuate stain on the cornea maybe due to?

a. failure to close the lids completely when blinking
b. a lens fit that is excessively flat
c. poorly blended secondary curves
d. solution sensitivity

Answer 38

A lens fit that is excessively flat

Choice A, failure to close the lids completely when blinking, would result in 3 and 9
o’clock staining. Choice B would cause apical staining. Choice D would usually cause a
very fine, diffuse superficial punctate keratitis (SPK) from limbus to limbus.

Question 39

In a Schirmer 1 test

Answer 39

A patient with an

unanesthetized eye and normal tear output should wet at lest 15mm of the filter paper in 5 minutes.

Question 40

The most powerful refracting surface of the eye is the ?

Answer 40

The answer is B
The cornea averages 43 diopters of refractive power. The retina is the innermost layer of
the eye and contains nerve cells that receive the image that we see and transmit it to the
brain. The crystalline lens plays a small role in the refraction of light with about 20
diopters of refractive power, accommodates to assist in bringing near objects into focus
and helps to focus the image on the retina. The ciliary muscle assists with accommodation
by contracting and allowing the lens to become thicker and more convex so it can
bring near objects into focus.

Question 41

Which keratometer readings indicate with the rule astigmatism.

A. 45.00 @ 175/44.50 @ 85

B. 48.00 @ 45 /46.50 @ 135

C. 44.50 @ 15/44.75 @ 105

D. 46.00 @ 180/46.00 @ 90

Answer 41

With-the-rule astigmatism is characterized with the flattest corneal meridian being at, or
, close to, the 1800 axis.

Question 42

Which keratometer readings indicate with the rule astigmatism.

A. 45.00 @ 175/44.50 @ 85

B. 48.00 @ 45 /46.50 @ 135

C. 44.50 @ 15/44.75 @ 105

D. 46.00 @ 180/46.00 @ 90

Answer 42

With-the-rule astigmatism is characterized with the flattest corneal meridian being at, or
, close to, the 1800 axis
C. 44.50 @ 15/44.75 @ 105

Question 43

When evaluating tear film break-up time:

a. Rose Bengal will give a more accurate reading than fluorescein.

b. fluorescein should be instilled in the eye and the patient not allowed to blink
until a reading is taken

c. a breakup time of less than 10 seconds may preclude success with contact lenses

Answer 43

The answer is C
Rose Bengal is attracted to devitalized cells; it is not used to stain the tear film. Break-up
time (BUT) testing is done by instilling fluorescein, having the patient blink once to spread
the fluorescein across the cornea and timing the interval between the blink and the
development of the first dry spot (tear break-up) on the cornea. Generally, a BUT of
greater than 10 seconds is needed for successful contact lens wear. Choice D is incorrect
because testing is done at the slit lamp, not the keratometer.