Determine Lens Type And Design Contact Lens

Front 1

An application of flourescein should be used in what situation?

Back 1

Evaluation of a rigid gas permeable lens fit.

Front 2

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

1. Decreasing overall lens diameter
2. Increasing overall lens diameter

Back 2

Decreasing the overall lens diameter.

Front 3

If a soft contact lens decenters laterally, exposing a portion of the patients liumbus, what change in parameter would improve this situation?

1. Decreasing lens diameter
2. Increasing lens diameter

Back 3

Increasing the lens diamter.

Front 4

When evaluating a diagnostic soft lens on a patient, you noitce that movement is sluggish after only a few minutes. Which of the following changes would you make to the lenses that are ordered for the patient?

1. Increase overall lens diamter
2. Steepen base curve
3. Flatten base curve

Back 4

By flattening the base curve, the fit will be loosened and movement will be increased. Increase and steepending the base curve will tighten the lense.

Front 5

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

K's 43.00 @ 180 / 46.00 @ 90
Rx -3.00 sphere

1. Soft toric lens
2. Spherical rigid gas permeable with increased center thickness
3. Truncated rigid gas permeable lens
4. Soft spherical lens

Back 5

Soft spherical lens -

Front 6

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

1. Hyperflange
2. Concentric design
3. Lenticular myoflange
4. Intrapalpebral Design

Back 6

Lenticular myoflange

Front 7

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

1. Spherical rigid gas permeable lens
2. Spherical soft lens
3. Soft toric lens
4. Back surface toric rigid gas permeable lens

Back 7

Soft toric lens

Front 8

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

K's 43.00 @ 180 / 44.00 @ 90
Rx -3.00 +1.00 x 90

Back 8

-2.00 D

to determine the rx of a rigid gas permeable lens, put the rx in minus cylynder form, -3.00 +1.00 x 90 becomes -2.00 -1.00 x 180. Next drop the cylinder. When fitting a lens "on K' order the sphere power corrected for vertex distance, when teh Rx is in the minus cylinder: -2.00

Front 9

To aid in the positioning of a rigid prism ballast lens riding too low and slipping underneath the lower lid, what would be helpful?

Back 9

Truncation - would help provide a flatter, thicker surface to interact with the lower lid, enabling the lens to rest in the proper position.

Front 10

The following rigid gas permeable diagnostic lens is placed on a patients 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?

1. 43.50 -0.50 -1.50 x 5 9.2
2. 43.50 -2.00 -1.50 x 5 9.2
3. 43.50 plano -1.50 x 95 9.2
4. 43.50 plano +1.50 x 5 9.2

Back 10

43.50 -0.50 -1.50 x 5 9.2

Put into minus cylinder form. plano 1.50 x 95 becomes +1.50 -1.50 x 5 - add spherical component to the existing spherical component *-2.00 plus +1.50 becomes -0.50)

Front 11

The following soft lens is placed on a patients 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?

1. 8.8 -3.25 14.0
2. 8.8 -4.00 14.0
3. 8.8 -4.75 14.0
4. 8.8 -5.25 14.0

Back 11

8.8 -4.75 14.0 - just add the -0.75 to the -4.00

Front 12

In an RGP lens, a poorly finished transitional zone between the optic szone and the lens edge can be evaluated by:

Back 12

Profile analyser - aids in evaluating the quality of the peripheral blends of an RGP lens.

Front 13

During the diagnostic evaluation of teh following patient, the lens rotates 10 degress to the right. Which of teh following lens parameters would you order for the patient?

Patients Refraction - -2.50 -1.00 x 170

Diagnostic lens 8.7 -2.50 -1.00 x 170

Back 13

8.7 -2.50 -1.00 x 160 - when it rotates to the left you add degrees, when to the right you subtract. so subtract the 10 degress *170 - 10 = 160

Front 14

Which of the following lens designs would not provide a good visiual result for this patient.

K's 42.50 @ 180 / 44.00 @ 90
R's -2.50 +1.50 x 90

1. Soft toric lens
2. Soft spherical lens
3. Spherical rigid gas permeable lens
4. Aspheric rigid gas permeable lens

Back 14

soft spherical lens will not correct the astigmatism in this patient so will not provide adequate vision.

Front 15

An excellent material for a patient with keratoconus would be:

Back 15

Fluoro Silicon Acrylate - rigid lens material

Front 16

A prism ballast RGP lens requres how much prism for proper orientation?

Back 16

0.75 to 1.50 D

Front 17

Which would be considered in the fitting of a keratoconus patient

1. Aspheric
2. McGuire
3. Soper
4. Tangent Streak

Back 17

Aspheric, McGuire and Soper lenses are recognized modalities for the management of keratoconus.

Front 18

The following soft lens is placed on a patients eye: 8.4 -2.00 14.2

An over-refraction is performed with the following results:
-1.00 -0.50 x 174

What lens paramters would you order for the patient?

Back 18

8.4 -3.25 14.2

Transpose to minus cylinder form. then determine the spherical equivalent (-1.25 in this case) and add this to the existing power.

Front 19

K's 45.00 @ 180 / 44.00 @ 90
Rx -3.00 +1.00 x 180

Upper lid positioned at the superior limbus:

Which of teh following set of lens specifications would best simulate an intrapalpebral rigid lens fitting?

1. 43.50 -1.50 8.5
2. 43.50 -1.50 9.5
3. 44.50 -2.00 8.5
4. 44.50 -2.50 8.5

Back 19

44.50 -2.50 8.5

Front 20

Given the following info, which ste 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.

1. 41.50 -1.50 9.5
2. 42.50 -2.50 8.5
3. 43.00 -2.50 9.5
4. 43.00 -3.00 8.2

Back 20

41.50 -1.50 9.5 - Lid attachment lenses are designed to fit with the upper edge of the lens positioned under the upper eye lid. (over 9.0 mm)

Front 21

Which bifocal design represents a translating design?

1. Diffraction
2. Crescent
3. Revers centrad
4. Concentric design

Back 21

Crescent design

Front 22

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

K's 42.00 @ 180 / 45.0 @ 90
Rx -3.00 -2.25 x 180

1. 42.00 / 45.00 -3.00 - 2.25 (rx form)
2. 42.00 -3.00 -2.75 x 177 prism ballasted
3. 42.00 -3.00
4. 45.00 - 3.00

Back 22

42.00 / 45.00 -3.00 -2.25 (rx form)

the base curves will parallel the K readings and the power in the lens will properly correct the astigmatism.

Front 23

The performance of a soft toric lens depends on:

Back 23

Corneal topography, lid shape, lid positioning and lid tightness should all be considered in pre-fit evalutation and selection lens type.

Front 24

Given the following, which of the RGP lens designs would you order to best correct this patients vision?

K's 45.00 @ 180 / 42.00 @ 90
Rx - 2.00 -4.25 x 90

1. 45.00 - 2.00
2. 42.00 - 2.00 - 4.25 x 90 prism ballasted
3. 42.00 -2.00
4. 42.00 / 45.00 -2.00 / -5.75 (drum readings)

Back 24

42.00 / 45.00 -2.00 / -5.76

a bitoric lens design will provide the best lens orientation on against the rule corneal topography.

Front 25

Given the following information, which RGP lens designs will best correct this wearers vision?

K's 42.50 @ 180 / 42.50 @ 90
Rx -3.00 -1.00 x 90

1. Bitoric design
2. Anterior toric design
3. Spherical design
4. Soper Cone design

Back 25

Anterior Toric design

the base curve will parallel the spherical cornea and the prism ballast will position the cylinder in the lens on the axis of the Rx.

Front 26

Given the following refraction and K readings, select the correct base curve and power recordings (drum readings).

K's 44.00 @ 180 / 41.00 @ 90
Rx -1.00 -3.00 x 90

1. 41.00 / 44.00 - 1.00 / -3.00
2. 41.00 / 44.00 -1.00 /-4.00
3. 41.00 / 44.00 -4.00 / -1.00
4. 44.00 / 41.00 -1.00 / -3.00

Back 26

41.00 / 44.00 -1.00 / -4.00

A toric rigid lens should always be recorded with the flat meridian first and teh steep meridian second. The total power in each meridian is written to correspond respectively.

Front 27

Which of the following is not necessary to consider when fitting RGP aphakic contact lenses?

1. Vertex distance
2. Minus-carrier lenticular designs
3. Proper lens centration
4. Hyperflange designs

Back 27

Hyperflange designs

A hyperflange would only be appropriate to consider for a high minus lens. All others are very importatn.

Front 28

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

Back 28

An aspheric lens

Front 29

An aphakic patient with K readings of 40.50 @ 180 / 41.25 @ 90, large palpebral fissures and flaccid lower lids is a good candidate for:

Back 29

A myoflange lenticular

this is best suited for aphakic patients with corneal curvatures flatter than 45.00 D, large palpebral fissures and flaccid lower lids.

Front 30

The patient has a horizontal visible iris diameter *HVID of 12.5 mm. The best inital soft diamter would be:

Back 30

13.5 mm

Rule of thumb for determining initial soft lens diameter is to choose a lens that is 2.00 mm larger than the cornea.

Front 31

A single cut aphakic lens is best suited for patients with _____ apertures and ________ corneas:

Back 31

Small / Steep

A single cut aphakic lens is best suited for paitens with small apertures and steep corneas.

Front 32

Where is the power curve on a spin-cast soft lens?

Back 32

The back suface

the power is on the posterior surface of a spin-cast soft lens.

Front 33

Keratoconus and penetrating keratoplasty fittings are best accomplished by which method?

Back 33

Diagnostic fitting

Due to irregular astigmatism secondary to keratoconus and penetrating keratoplasty (PKP), reliable K readings are not obtainable, therefore a trial fitting is best.

Front 34

Which ametropia frequently results in high riding rigid lenses?

Back 34

High Myopea

Due to the increased edge thickness of a high minus lens, it will frequently catch under the upper lid causing it to ride high.

Front 35

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

Back 35

Aspheric

Aspheric lens designs are the only bifocals which do not have independent near and distant zones.

Front 36

Which kind of lens will correct a residual astigmatism, moderat astigmatism and low astigmatism?

Back 36

A toric soft lens

Front 37

A lens fitted for keratoconus should:

1. Flatten the apex
2. Ride high
3. Align the apex
4. Ride low

Back 37

Align the apex

A keratoconus lens should center well with good movement and a 3 mm feather touch over the apex of the cone.

Front 38

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

1. Keratitis sicca
2. Trichiasis
3. Recurrent erosion
4. Keratoconus

Back 38

Recurrent erosion

Front 39

The best option for patients with Giant Papillary Conjuctivitis *GPC or those who are cooks or hairdressers is:

1. Tinted soft lenses
2. Disposable lenses for daily wear only
3. Traditional soft lenses that are replaced on an annual basis
4. Extended lens wear

Back 39

Disposable lenses for daily wear only

Patients who are heavy depositers will benefit from frequent replacement of their lenses.

Front 40

Which of the following is a translating bifocal lens design?

1. Concentric
2. Aspheric
3. Diffractive
4. Segmented

Back 40

Segmented

Concentric, Aspheric and Diffractive are all simultaneous image lenses

Front 41

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

Back 41

Soft toric lens

These designs are utilized by various soft lens manufacturers to maintain lens positioning.

Front 42

In choosing the diameter of a soft lens, what is the general rule of thumb?

Back 42

2.00 mm larger than the HVID

Front 43

K's 42.00 @ 170 / 43.00 @ 80
Rx -3.00 -1.00 x 170

Given the above information, the following diagnostic toric soft lens was used: 8.8 -3.00 -1.00 x 180

During diagnostic evaluation, the above lens rotated 10 degrees clockwise. The lens ordered should have an axis of

Back 43

180 degrees

When a diagnostic soft toric lens rotates clockwise, then the amount of rotation should be added. If counterclockwise it should be subtracted.

Front 44

Which of the following statements is correct?

1. High Dk RGP lenses have greater stability and deposit resistance than lower Dk materials.

2. Use of an enzymatic cleaner is mandatory with fluor-silicone acrylate materials

3. Fluoro-silicone acrylate materials have "non stick" qualities that enable patients to blink protein and other deposits off the lens surface.

4. Silicone acrylate materials have a positively charged surface that repels lipid and protein deposits

Back 44

Fluoro-silicone acrylate materials have non stick qualities that enable patients to blink protein and other deposits off the lens surface.

1 - incorrect bc high DK RGP lenses contain more silicone which decreases stability and deposit resistance.

2 - incorrect because the fluorinated materials are resistant to protein build up.

4 - incorrect because silicone/acrylate materials have negatively charged surface that attracts lipid and protein deposits.

Front 45

Given the following information, which of the follwing is correct?

K's 42.00 @ 180 / 42.00 @ 90
Rx -3.00 -2.00 x 180

1. A back surface toric RGP lens will probably be necessary to achieve optimum visual acuity.

2. A bitoric RGP lens will probably be necessary to achieve optimum visual acuity.

3. A soft spherical lens will provide the best fit and visual acuity because the paitent has a spherical cornea.

4. A front surface toric RGP lens will probably be necessary to correct the patients residual astigmatism.

Back 45

A back surface toric RGP lens will probably be necessary to achieve optimum visual acuity.

Front 46

A patients K readings are 43.50 @ 180 / 41.50 @ 90. A spherical RGP lens can be expected to:

1. Displace down and in or down and out with each blink.

2. Position under the upper lid to provide a superior lid attachment, alignment fit

3. Lock on to the cornea nasally or temporally

4. Establish a fulcrum at 3 and 9 o'clock in the horizontal medium

Back 46

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

This patient has against the rule astigmatism and the cornea has a vertical ellipsoidal shape.

Front 47

What special RGP lens design would be beneficial for this patient given the following information.

K's 44.00 @ 180 / 46.50 @ 90
Rx - 11.00 +2.50 x 90

1. Hyperflange
2. Back toric design
3. Thick edge design
4. Myoflange

Back 47

Hyperflange

The design reduces the edge thickness of a high minus lens increasing patient comfort and allowing the lens to center better.

Front 48

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

Patients Refraction -3.00 -1.25 x 160
Diagnostic lens 8.4 -3.00 -1.25 x 180 14.5

1. 8.4 -3.00 -1.25 x 160 14.5
2. 8.4 -3.00 -1.25 x 170 14.5
3. 8.4 -3.00 -1.25 x 180 14.5
4. 8.4 -3.00 -1.25 x 10 14.5

Back 48

8.4 -3.00 -1.25 x 170 14.5

To compensate for rotation of a diagnostic soft toric lens, add the amount of rotation if it rotates to your left and subtract the rotation if it rotates to your right.

Front 49

A patient is diagnostically fit with a rigid 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 would you order?

1. 42.00 -2.50 10.00
2. 42.50 -3.00 9.0
3. 43.00 -3.50 9.5
4. 43.50 -3.50 9.0

Back 49

42.50 -3.00 9.0

this will flatten the lens to cornea relationship because it reduces the lens diamter without altering *steepening the base curve.

Front 50

Contact lens are most often specified in?

Back 50

Back vetex power

Phoropters, spectacles and trial lenses are all specified in back vertex power. Therefore, to maintain consistancy, most contact lenses are also specified in back vertex power.