Contact lens practice for state exam

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

Antihistamines

Which term refers to sensitivity to light

Photophobia

This following is an example of what type of astigmatism

K's 42.50F@ 180 / 40.50@90

Against-The-Rule Astigmatism

The Cornea receives nutrients from

Aqueous humor, Tears, Limbal blood vessels

The increased loss of ability of the crystalline lens to accommodate is called

Presbyopia

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

Slit lamp

The classic model of the pre-corneal tear film is composed of three layers. They are:

lipid, aqueous, Mucin

Transpose the following rx into minus cylinder form

-4.50 + 1.25 X 94

-3.25 -1.25 X 4

The average pH value of the human tear is

7.4

If the manufacturer's guidelines suggest a minimum of 4 hours for disinfection, what would you suggest to the patient?

A minimum of 4 hours is required

The main supply of oxygen to the corneal epithelium is derived from the

Tear film

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

Amblyopia

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

-1.00D

Which step should be performed first when taking keratometer measurements

Focus the eyepeice

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

lenticular astigmatism

Ocular signs of aging include:

Tear film Abnormalities, Reduced lid elasticity, lens opacities, loss of accommodation

Transpose the following Rx into minus cylinder form:

+1.50+1.00 x 75

+2.50-1.00 x 165

The pre-corneal tear film provides:

A smooth optical surface, Metabolic nutrients to the epithelium

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

Epithelium, Bowman's layer, Stroma, Descemet's membrane, Endothelium

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?

Endothelium

A normal tear break-up time is:

10-12 seconds

A whitish haze in the peripheral corneal stroma which does not stain and is often seen in the elderly is know as:

Arcus Senilus

Patients with keratitis sicca are more prone to?

Secondary infections

Upon removal of the crystalline lens, the patient is

Aphakic

The following Rx represents

OD +2.00 = 20/20

OS -3.00-2.00 x 180 = 20/20

Anisometropia

The patient in the previous question will best achieve stereopsis with which of the following modalities?

Contact Lenses

Tom's spectacles with a power of -12.00+0.50 x 090, sit 10 mm in front of his cornea. The likely soft Contact lens prescription for Tom would be?

-10.50

The keratometer is an instrument used to measure

Corneal curvature

The average life span of corneal epithelial cell from mitosis through maturation and desquamation most nearly approximates?

One week

Which auxiliary trial lens will extend the keratometer range to approximately 61.00 D?

+1.25

Wearing lenses in high altitudes and dry environments may result in complaints of all but the following?

Chalazion

The first line of defense on the protective system of the eye is formed by the:

Eyelids

Transient keratometric mire distortion is usually due to ?

Pre - ocular tear film

In against-the-rule astigmatism, the steepest corneal meridian?

Is at or near 180 degrees

An inability to bring all of the keratometer mires into focus at the same time may indicate?

Irregular astigmatism

In an alignment lid attachment GP fit, the fluorescein pattern should show?

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

In a GP wearer, an arcuate stain on the cornea may be due to ?

Poorly blended secondary curves

In a Schirmer I test

A patient with an unanesthetized eye and normal tear output should wet at least 15 mm of the filter paper in 5 minutes

The most powerful refracting surface of the eye is the

Cornea

Which keratometer reading indicated with-the-rule astigmatism

44.50 @ 15 / 44.75 @ 105

When evaluating tear film break-up time:

A break-up time of less than 10 seconds may preclude success with contact lenses

The preservative in contact lens solutions

Is formulated to keep microorganisms from multiplying in a bottle of contact lens solutions after it has been opened

Results of a refraction show a patient to see best at distance with a power of +1.25+1.00 x 95 and at near with a power of +2.50+1.00 x 95. What is the "add" power

+1.25D

A pre-presbyopic myopic patient who is still able to read with single vision glasses may find that:

They are unable to see fine print when fit with contact lenses

Amy's +8.50 D spectacles sit 12 mm from the cornea. The power of a soft contact lens for Amy, properly vertexed, would be?

+9.50

Which of the following choices would work best for the patient's visual need given the following information:

K's 44.00 @ 180 / 45.25 @ 90

Rx -3.00+0.25 x 90

Spherical soft lens

Which of the following set of lens specifications would best simulate an intrapalpebral GP fitting given the following information?

K's 42.00 @ 180 / 43.00 @ 90

Rx -2.00-1.00 x 180

Upper lid positions 2 mm above the superior limbus

42.50-2.50 8.5

Which contact lens would best correct this patient's visual needs, given the following information:

K's 46.00 @ 180 / 45.50 @ 90

Rx -3.00+1.50 x 90

A soft toric lens

The average HVID for a patient is

11.5

If a patient has 1.50 of refractive cylinder and keratometer readings of 44.00 @ 180 / 44.50 @ 90, you would expect a spherical gas permeable lens to?

Result in residual astigmatism

Application of fluorescein should be used in which of the following situations?

Evaluation of a gas permeable lens fit

If the diagnostic gas permeable lens placed on the eye results in minimal movement, which of the following will increase the movement on the lens ordered for the patient?

Decreasing overall lens diameter

Contact lens techicians work with prescriptions in minus cylinder form because?

The lacrimal lens is a minus cylinder lens

Rx OU -3.00-0.50 x 180, Add +1.25 D. If spherical soft lenses are being fit using the monovision technique, what is the desired power for the eye fitted for near?

-2.00

Which of the following lens designs would provide the best visual result for this patient?

K's 43.00 @ 180 / 46.00 @ 90

Rx -3.00 sphere

Soft spherical lens

Which edge design is recommended for a +15.00 D aphakic GP lens?

Lenticular Myoflange

Which of the following lens designs would provide the best visual result for this patient?

k's 42.00 @ 180 / 42.50 @ 90

Rx -3.50-1.75 X 180

Soft toric lens

What Rx would be ordered for a gas permeable lens fit on K

K's 43.00 @ 180 / 44.00 @ 90

Rx -3.00+1.00 x 90

-2.00 D

To aid in the positioning of a GP prism ballast lens riding too low and slipping underneath the lower lid which of the following might be helpful?

truncation

The following gas permeable diagnostic lens is placed on a patient's eye:

43.50 -2.00 9.2

An over-refraction is performed with the following results:

plano+1.50 x 95

Which of the following lens parameters would you order for the patient?

43.50 -0.50-1.50 x 005 9.2

The following soft lens is placed on a patient's eye: 8.8 -4.00 14.0

An over refraction is performed resulting in -0.75 D sphere. Which of the following lens parameters would you order for the patient?

8.8 -4.75 14.0

In a GP lens, a poorly finished transitional zone between the optic zone and the lens edge can be evaluated by?

Profile analyzer

During the diagnostic evaluation of the following patient you observe that the lens rotates 10 degrees to the right, Which of the following lens parameters would you order for the patient?

Patient's refraction -2.50-1.00 x 170

Diagnostic lens 8.7 -2.50-1.00 x 170

8.7 -2.50-1.00 x 160

Which of the following lens designs would not provide a good visual result for this patient?

K's 42.50 @ 180 / 44.00 @ 90

Rx-2.50+1.50 x 90

soft spherical lens

In prescriptions of 4.00 D or greater, fitting contact lenses requires compensating the power for the change in vertex distance. When moving from the spectacle plane to the corneal plane, the compensated power will be?

More plus

A prism ballast GP lens requires how much prism for proper orientation?

0.75 to 1.50 D

The longer the radius of curvature of a contact lens?

The flatter the lens

The following soft lens is place on a patient's eye

8.4 -2.00 14.2

An over refraction is performed with the following results:

-1.00-0.50 x 174

Which of the following lens parameters would you order for the patient?

8.4 -3.25 14.2

Given the following information:

K's 46.00 @ 180 / 44.00 @ 90

Rx -3.00+1.00 x 180

Upper lid positioned at superior limbus. Which of the following set of lens specifications would best simulate an intrapalpebral GP lens fit?

44.50 -2.50 8.5

Given the following information, which set of lens specifications would best simulate a lid attachment rigid lens fitting?

K's 42.00 @ 180 / 43.00 @ 90

Rx -2.00-0.87 x 180

Upper lid positioned 2 mm below the superior limbus

41.50 -1.50 9.5

Which of the following bifocals designs represents a translating design

Crescent design

Given the following information, which of the listed rigid lens designs would order to best correct this wearer's vision?

K's 42.00 @ 180 / 45.00 @ 90

Rx -3.00-2.25 x 180

42.00/45.00 -3.00-2.25 ( Rx form )

Up until the recent introduction of silicone hydrogel lenses the Dk/t of previous hydrogel lenses was limited by

Water content and center thickness

Given the following information, which of the following GP lens designs would you order to best correct this patient's vision?

K's 45.00 @ 180 / 42.00 @ 90

Rx -2.00-4.25 x 90

42.00/45.00 -2.00/-5.75

Given the following information, which of the following GP lens designs will best correct this wearer's vision?

K's 42.50 @ 180 / 42.50@ 90

Rx -3.00-1.00 x 90

Anterior toric design

Given the following refraction and K readings, select the correct base curve and power recordings

44.00 @ 180 / 41.00 @ 90

Rx -1.00-3.00 x 90

41.00 / 44.00 -1.00 / -4.00

Fitting soft lenses steeper than K will usually result in

Fluctuations in vision following the blink

A bifocal lens in which the power gradually changes from the central area of the lens to a periphery is known as

An aspheric lens

How many diopters of power will bring parallel rays of incident light to focus at a distance of one meter?

One diopter

The patient has a horizontal visible iris diameter of 12.5 mm. the best choice for initial soft lens diameter would be

14.5

In which of the following types of corneal astigmatism is a GP lens most indicated?

Irregular

Spherical equivalent powers position which of the following on the retina?

Circle of least confusion

Keratoconus and penetrating keratoplasty fittings are best accomplished by which of the following methods?

Diagnostic fitting

The following ametropia frequently results in high riding rigid lenses

High myopia

A good example of a bifocal contact lens that may rotate without vision impairment is

Aspheric

A soft toric lens will correct

Residual Astigmatism, Moderate Astigmatism, Low Astigmatism

In calculating the prescription for a rigid lens, one must"

First transpose the patient's prescription into minus cylinder form

Therapeutic soft lenses should be fit with minimal movement in which case?

Recurrent erosion

A rigid lens correct astigmatism by

Forming a new spherical refracting surface in front of the cornea

Which of the following is a translating bifocal lens design?

Segmented

Prism ballast, double slab-off and peri-ballast are all what type of lens design?

Soft toric

Which of the following are two methods of stabilizing the rotation of rigid bifocal contact lenses?

Truncation and prism ballast

K's 42.00 @ 170 / 43.00 @ 80

Rx -3.00-1.00 x 170

Given the Rx and K's, the following diagnostic toric soft lens was used

8.8 -3.00-1.00 x 180

During the diagnostic evaluation the observer notes the lens rotated 10 degrees clockwise.

The lens ordered should have an axis of?

180 degrees

The FDA classification for disposable lenses means

The lens is disposed of after removal

Given the following information

K's 42.00 @ 180 / 42.00 @ 90

Rx -3.00-2.00 x 180

A front surface toric gp lens will probably be necessary to correct the patient's residual astigmatism

A patient's K reading are 43.50 @ 180 / 41.50 @ 90. A spherical GP lens can be expected to

Displace down and in, or down and out with each blink

Which special GP lens design would be beneficial for this patient given the following information?

K's 44.00 @ 180 / 46.50 @ 90

Rx -11.00+2.500 x 90

Hyperflange

During the diagnostic evaluation of the following patient you note the lens rotates 10 degrees to your left. Which of the following lens parameters would you order for the patient?

Patient's refraction -3.00-1.25 x 160

Diagnostic lens 8.4 -3.00-1.25 x 180 14.5

8.4 -3.00-1.25 x 170 14.5

A patient is diagnostically fit with a gas permeable lens with the following parameters 42.50 -3.00 9.5. If you wish to flatten the lens to cornea relationship, which of the following lenses would you order?

42.50 -3.00 9.0

The tolerance for the overall lens diameter according to the ANSI standards is

+/- 0.05