Quiz For Contact Lens Instrumentation

1 point(s)

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1.66

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1.523

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1.490

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1.3375

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1 point(s)

The keratometer measures an area of the front surface of the cornea of approximately

1-3 mm

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2-4 mm

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5-7 mm

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8-10 mm

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1 point(s)

Diopters to mm conversion cam be accomplished___________

by applying a formula

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by referencing a diopters to radius conversion chart

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by referencing the horizontal and vertical measuring drum on most keratometers

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all of the above

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1 point(s)

The following formula can be used to calculate the power in diopters when the radius of curvature is known:

D = n-1/ R

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R = n-1/ D

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D = 1/ f

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None of the above

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1 point(s)

The following formula can be used to calculate the radius of curvature when the power in diopters is known:

D = n-1/ R

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R = n-1/ D

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R = 1/ f

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None of the above

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1 point(s)

The keratometer eyepiece ____________

only needs to be adjusted one time for all operators

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needs to be adjusted each time there is a new patient

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needs to be adjusted each time there is a new operator

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never requires adjustment on the newer instruments

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1 point(s)

When orienting the keratometer, the instrument body should be rotated to allow the axial scale to read exactly_____________at the axis marks

60 ° and 150°

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45 ° and 135°

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90° and 180°

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the rotation of the instrument is not important

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1 point(s)

Once the keratometer and the patient have been properly oriented, the patient sees:

a green fixation target in the tube of the instrument

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a reflection of his own eye

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a reflection of the operator's eye

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the horizontal measuring drum

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1 point(s)

When focusing the keratometer, the operator will see:

a reflection of his own eye

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a green fixation target

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a reflection of the patient's eye

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images of the target mire

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1 point(s)

Focusing a Keratometer:

depends solely on the sharpness of the target mire

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is accomplished more precisely by coincidence of overlapped focusing circles appearing

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depends on the focus of the minus sign

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is not necessary for most patients

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1 point(s)

The axis of a cylinder can be found when:

the tips of the plus signs just touch

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the minus signs overlap

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the focusing circle appears single and sharp

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"triple alignment" is achieved

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1 point(s)

To measure the corneal surface power in the horizontal principal meridian

move the tips of the plus sign until they just touch

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move the minus sign until it is exactly superimposed on the minus sign of the central focusing circle

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move the plus sign until it is exactly superimposed on the plus sign of the central focusing circle

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rotate the keratometer tube while looking into the eyepiece

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1 point(s)

When measuring an astigmatic cornea

both principal meridians will come in focus at the same time

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it is impossible to get both meridians to come into focus at one time

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the axis is always 90 or 180 degrees

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the axis is not important

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1 point(s)

The range of curvatures in diopters the keratometer is capable of measuring without applying an auxiliary lenses is:

44.00 D to 59.00 D

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46.00 D to 48.00 D

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36.00 D to 52.00 D

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29.00 D to 49.00 D

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1 point(s)

To obtain a keratometer reading in a high diopter range, fron 52.00 D to 61.00 D place a ______________ test lens sphere over the central aperture of the Keratometer mire.

+1.25 D

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– 1.00 D

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+ 1.50 D

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– 1.25 D

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1 point(s)

To obtain a keratometer reading in the lower diopter range, from 30.00 D to 42.00 D place a ____________test lens sphere over the central aperture of the Keratom eter mire.

+ 1.25 D

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– 1.00 D

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+ 1.50 D

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– 1.25 D

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1 point(s)

Referring to the “High Power” ( +1.25 table) on page 9, what is the corneal power in diopters when the drum reading is 45.50?

54.36

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53.631

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52.903

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53.048

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1 point(s)

Referring to the “Low Power” ( -1.00 table) on page 9, what is the corneal power in diopters when the drum reading is 40.00?

32.804

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33.876

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34.305

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35.484

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1 point(s)

A keratometer can also be used to measure the _______________of contact lenses.

radius of curvature

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power in diopters

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optical zone radius

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center and edge thickness

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1 point(s)

When recording keratometer readings:

the horizontal meridian is generally recorded first followed by the vertical meridian

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a meridian is considered horizontal if it falls 30° or either side of 180

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a meridian is considered vertical if it falls 30° or either side of 90

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all of the above are true

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1 point(s)

The slit lamp is also referred to as

burton lamp

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radiuscope

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lens measure

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biomicroscope

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1 point(s)

The microscope on the slit lamp has various settings. Most instruments have magnification abilities ranging from:

6X to 40X

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10X to 20X

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30X to 40X

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50X to 60X

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1 point(s)

When using a slit lamp, the majority of the microscopic eye exam is done:

while using a cobalt blue filter

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with little or no illumination

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with the light beam set at maximum height but with a narrow width that produces a slit of light

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with the light beam set at maximum height and the beam opened all the way

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1 point(s)

In______________illumination light is spread evenly over the entire observed surface.

diffuse illumination

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direct illumination

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indirect illumination

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direct retroillumination

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1 point(s)

In______________illumination light is directed at a specific object and is especially useful in determining the depth of abnormalities.

diffuse illumination

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direct illumination

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indirect illumination

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direct retroillumination

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1 point(s)

In______________illumination light abnormalities are not illuminated by shining the slit beam directly on them, rather they are lit up by light that is reflected off an uninvolved area.

diffuse illumination

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direct illumination

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indirect illumination

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direct retroillumination

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1 point(s)

When using a slit lamp to evaluate a contact lens fit, redness at the corneal/limbal junction for 360 degrees may indicate:

signs of a tight lens

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signs of a loose lens

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corneal hypoxia

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corneal staining

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1 point(s)

When using a slit lamp to evaluate a contact lens fit, a lens which drops more than 1.0 mm when the patient looks up may indicate:

signs of a tight lens

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signs of a loose lens

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corneal hypoxia

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corneal staining

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1 point(s)

When using a slit lamp to evaluate a contact lens fit, generalized corneal edema and neovascularization may indicate:

signs of a tight lens

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signs of a loose lens

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corneal hypoxia

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corneal staining

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1 point(s)

When evaluating a rigid contact lens fit with fluorescein and a slit lamp, a thin film of dye spread under the entire lens with slight pooling at the periphery indicates:

a loose fit

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a tight fit

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a good fit

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an astigmatic fit

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1 point(s)

When evaluating a rigid contact lens fit with fluorescein and a slit lamp, a band of dye running horizontally or vertically indicates:

a loose fit

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a tight fit

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a good fit

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an astigmatic fit

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1 point(s)

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1 point(s)

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Quiz For Contact Lens Instrumentation

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