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III. Adv CL Lab > Practical > Flashcards

Practical Flashcards

1
Q

What is the induced amount of refractive error when a soft toric lens rotates 10deg? 1. 20 deg? 2. 30 deg? 3

A
  1. 33% of cyl
  2. 66% of cyl
  3. 100% of cyl
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2
Q

How does a front surface toric GP lens read on lensometer? 1. On radioscope? 2

A
  1. toric

2. sphere

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3
Q

How does a botoric GP lens read on lensometer? 1. On radioscope? 2

A
  1. toric

2. toric

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4
Q

How does a back surface toric GP lens read on lensometer? 1. On radioscope? 2

A
  1. toric

2. toric

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5
Q

How does a warped spherical GP lens read on lensometer? 1. On radioscope? 2

A
  1. sphere but may not clearly focus

2. toric

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6
Q

What conditions would make for a spherical GP lens to be the best GP option? 1. How should these be fit? 2

A
  1. corneal cyl less than 2D and roughly equal to refractive cyl
  2. fit BC relative to flat K
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7
Q

What conditions would make for a front surface toric GP lens to be the best GP option? 1. How should these be fit? 2

A
  1. low corneal cyl but usually greater than 0.75D residual cyl
  2. fit BC relative to flat K, calculated with OR
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8
Q

What conditions would make for a back surface toric GP lens to be the best GP option?

A

refractive cyl 1.5x corneal cyl

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9
Q

What conditions would make for a bitoric GP lens to be the best GP option? 1. How should these be fit? 2

A
  1. corneal toricity greater than 2D or less if limbal to limbal cyl
  2. low toric simulation or saddle fit
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10
Q

What is the bitoric GP fit called when the difference in BC is equal to the difference in power in the lens?

A

spherical power effect (SPE)

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11
Q

What is the bitoric GP fit called when the difference in BC is NOT equal to the difference in power in the lens?

A

cylinder power effect (CPE)

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12
Q

What is done in order for a bitoric GP lens to be considered a low toric simulation? 1. When is this best? 2

A
  1. fit horiz meridian on K and vert meridian 0.75D flat to promote vert movement
  2. WTR cornea
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13
Q

What is done in order for a bitoric GP lens to be considered a saddle fit? 1. When is this best? 2

A
  1. fit horiz and vert meridians on K

2. WTR, ATR or oblique

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14
Q

What are the benefits of GP multifocals?

A
  1. Better vision

2. better options for astigmats

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15
Q

What are the pre fitting conversations and considerations before fitting with GP Multifocals?

A
  1. adaptation
  2. visual needs
  3. dominant eye determination
  4. lid position
  5. pupil size
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16
Q

What makes for the ideal translating GP candidate?

A
  1. critical visual demands (usually distance and near)

2. lower lid positioned at or near lower limbus with good tonicity

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17
Q

How are translating GP lenses fit?

A
  1. slightly flatter than K to promote good translation
  2. in primary gaze, seg line should sit at within 1mm of pupil margin
  3. in downgaze, seg line should bisect at least half of pupil
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18
Q

What should be done when a lens or segment sits too high in a translating MF GP?

A
  1. inc prism

2. dec seg height

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19
Q

What should be done when there is fluctuating vision in a translating MF GP?

A

inc prism and or truncate to improve stability

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20
Q

What should be done when there are complaints of flare or ghosting in a translating MF GP?

A
  1. evaluate lens position and optic zone position in relation to pupil
  2. ensure pt isn’t catching the seg line in primary gaze
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21
Q

What should be done when there is poor translation in a translating MF GP?

A
  1. evaluate lid interaction (inc overall diameter or seg height)
  2. confirm pt drops eyes
  3. evaluate BC and edge clearance (flatten BC or peripheral curve can help translate)
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22
Q

What makes for the ideal simultaneous MF GP candidate?

A
  1. early presbyopes
  2. non critical visual demands
  3. high intermediate distance demands
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23
Q

For a simultaneous MF GP, what is the rate of flattening referred to as? 1. As it becomes larger, what happens to the add power? 2

A
  1. eccentricty

2. greater

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24
Q

What is the most important factor for good vision with simultaneous MF GPs?

A

centration

25
Q

Are front surface aspheric simultaneous MF GPs center distance or center near? 1. How are these fit? 2

A
  1. center near

2. flatter than posterior surface (less warpage)

26
Q

Are back surface aspheric simultaneous MF GPs center distance or center near? 1. How are these fit? 2

A
  1. center distance

2. steeper (more warpage)

27
Q

What kind of corneal warpage is the result of back surface aspheric simultaneous MF GPs?

A

mid peripheral corneal flattening

28
Q

What should be done when there is superior decentration of a simultaneous MF GP?

A
  1. steepen BC

2. consider switching to front surface toric if need to steepen significantly

29
Q

What should be done when there is inferior decentration of a simultaneous MF GP?

A
  1. inc OAD

2. flatten BC

30
Q

What should be done when there is lateral decentration of a simultaneous MF GP?

A
  1. steepen BC
  2. consider switching to front surface toric if need to steepen significantly
  3. increase OAD
31
Q

What should be done when there is poor DVA and good NVA of a simultaneous MF GP?

A

superiorly decentered or flat lens so steepen BC or dec OAD

32
Q

What should be done when there is good DVA and poor NVA of a simultaneous MF GP?

A
  1. push plus on OR

2. if lens not translating, inc OAD or flatten BC

33
Q

What should be done when there is poor DVA and poor NVA of a simultaneous MF GP?

A

laterally decentered so inc OAD

34
Q

What changes does orthoK do to the eye?

A

redistribution and compression of the epithelial tissue

35
Q

What makes for the ideal orthoK patient?

A
  1. myopia -0.50 to -6.00
  2. less than 1.75D WTR corneal cyl or less than 1.00D ATR corneal cyl
  3. sphere greater or equal to cyl power
  4. little or no lenticular astig
  5. final K greater than or equal to 37.00D
  6. no limbus to limbus corneal astig
36
Q

How wide is the optic zone of the Paragon CRT lens? 1. Return zone? 2

A
  1. 6mm

2. 1mm

37
Q

How many mm of treatment area should there be for a orthoK less?

A

4mm

38
Q

What are the increments that the return zone depth is available in? 1. Landing zone angle? 2. Base curve? 3

A
  1. 25microns
  2. 1deg
  3. 0.10mm (but not done to change fit)
39
Q

How much does a 1deg change in landing zone angle affect the sag depth of the orthoK lens?

A

15microns

40
Q

How much does a 0.10mm change in base curve affect the sag depth of the orthoK lens?

A

7 microns

41
Q

How much edge clearance is wanted over the majority of the orthoK lens?

A

0.30 to 0.75mm

42
Q

How long does it take for full treatment from orthoK lenses to be in effect?

A

up to 2 weeks

43
Q

What is the follow up schedule for orthoK lenses? 1. What should be done at each visit? 2

A
  1. 1wk, 2wks, 1month, 3months

2. VA, manifest Rx, topography, corneal health

44
Q

What should be done when there is superior decentration of an orthoK lens?

A

inc RZD in 25micron steps until centration achieved

45
Q

What should be done when there is lateral decentration of an orthoK lens?

A

inc RZD in 25micron steps until centration achieved

46
Q

What should be done when there is inferior decentration of an orthoK lens?

A
  1. dec LZA by 1deg if necessary

2. in no improvement, return to original LZA and dec RZD in 25micron increments

47
Q

If a -1.00D over refraction is found following orthoK treatment, what should be done to the lens?

A

0.20mm flatter BC

48
Q

What is the key component of scleral lenses?

A

sagittal depth

49
Q

How much central clearance is ideal for a scleral lens? 1. Limbal clearance? 2

A
  1. less than 250 to 300microns

2. 50microns or more

50
Q

What part of the scleral fit set should be used for normal or mild keratoconus (less than 45D)? 1. Moderate (45 to 52D)? 2. Advanced or severe (52D+)? 3

A
  1. lower 1/3 of set
  2. middle 1/3
  3. upper 1/3
51
Q

What should be put in the scleral lens for insertion?

A

non preserved saline (Addi Pak or LacriPure)

52
Q

How does a 0.10mm BC change in a scleral lens change the lens power? 1. A 100micron change in sag height? 2

A
  1. 0.50D

2. 0.12D

53
Q

What are the aspects that need to be assessed in a scleral lens fit?

A
  1. clearance
  2. conjunctival blanching
  3. vessel impingement
54
Q

How should scleral lenses be cleaned?

A
  1. non abrasive cleaner (Boston Simplus, Clear Care, Menicare)
  2. rinse with non preserved saline
55
Q

What type of hydrogels are non ionic? 1. Which one has high H2O? 2. What deposits accumulate on these? 3

A
  1. types I and II
  2. type II
  3. lipid
56
Q

What type of hydrogels are ionic? 1. Which one has high H2O? 2. What deposits accumulate on these? 3

A
  1. types III and IV
  2. type IV
  3. protein
57
Q

What is the appropriate initial BC for Duette lenses? 1. What would the OR be for this lens? 2

A
  1. 0.50D steeper than flat K

2. -0.50D

58
Q

What is the best skirt to initially fit for Duette lenses?

A

flat skirt. Then medium if decentered

III. Adv CL Lab (1 decks)

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