Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OPTOM 430 Test > Sem 1 > Flashcards

Sem 1 Flashcards

1
Q

Full time wear of contact lenses is when the patient wants to wear the lenses how often?

A

5-7 days per week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Part time wear of CLs is when the Px wants to wear the lenses how often?

A

occasional wear or only a few times per week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Daily wear is?

A

wearing CLs during waking hours only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Extended wear is?

A

wearing CLs continuously including overnight use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Disposable CLs are?

A

replaced (or diposed of) at greater frequency - daily, fortnightly, monthly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Conventional CLs are replaced how often?

A

annually

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Spherical RGPs fit what type of corneas?

A

near spherical cornea and any refractive error where the refractive astigmatism is mostly corneal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Spherical SCLs fit on what type of corneas?

A

most corneas and any refractive error with low refractive astigmatism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Front toric RGPs fit what type of corneas?

A

near spherical corneas and where there is significant refractive astigmatism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Toric SCLs fit what type of corneas?

A

most corneas and where there is significant refractive astigmatism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Bitoric/back toric RGPs fit on what type of corneas?

A

highly astigmatic corneas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Multifocal/Bifocal CLs have both RGP and SCL choices for patients requiring?

A

an ADD component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Other types of contact lenses? (6)

A 
color SCL
prosthetic SCL
semi scleral RGPs
reverse geometry RGPs
OTK RGPs
post-surgical lenses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

A positive spectacle lens becomes more or less positive when brought to the ocular plane?

A

more positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ΔK is the?

A

amount of corneal astigmatism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

With ΔK, which K value is flat and which one is steep?
K1 @ _____?
K2 @ _____?

A 
K1 = flat
K2 = steep
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

ΔK = ?

A

K1 - K2 x flat axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Refractive astigmatism that is significant and primary due to corneal astigmatism in origin is optically best managed with a?

A

RGP CL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The corneal diameter is also known as?

A

Horizontal visible iris diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Corneal diameter is relevant in determining what parameter of a contact lens?

A

overall diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which keratometer can measure along two principle meridians with one measurement?

A

Bausch and Lomb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which keratometer can only measure one principle meridian at a time?

A

Javal-Schiotz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Keratometers are limited to what three things?

A

restricted to spherocylindrical surfaces
3mm central area only
greatly affected by user and focusing error

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The range of a keratometer can be extended. For steep corneas a _____ trial lens is used and for fat corneas a _____ trial lens is used

A

+1.25

-1.00

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Videokeratoscopes measure how much area?

A

central 6-10mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

If the rings on a placido disc are spaced further apart this means that the cornea is?

A

flat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Normal axial patterns observed from topography maps? (5)

A 
round
oval
symmetric bow tie
asymmetric bow tie
irregular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What does thhe tangential display of a topographer do?

A

shows more discrete changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

The following characteristics apply to which topography map type?

  • measures radius of curvature to a comparable sphere
  • centers of rotation fall on the axis defined by videokeratoscope
  • reasonably represents refractive
  • involves smoothening
A

axial map/sagittal map

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The following characteristics apply to which topography map type?

  • Is not constrained by centers of rotation falling on axis of videokeratoscope
  • more accurately depicts the irregularity and location
  • shows local irregularity
A

tangential maps/instantaneous local map

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Keratometers can be used to? (5)

A 
measure normal variations
look at pathology/abnormal corneas
identify irregular corneas
monitor corneal shape changes
simulate RGP lens on eye fitting relationship
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

On a topography map, would you expect the hotter colors to run vertically or horizontally for a WTR astigmatic cornea?

A

vertically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Astigmatic corneas can be categorised into irregular astigmatism and regular astigmatism. What angle α is the boundary between the two?

A

20
ie α greater than 20 degrees = irregular astigmatism
α smaller than 20 degrees = regular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the term given to a flat cornea?

A

keratoplana

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Pellucid marginal degeneration is thinning of which part of the cornea?

A

inferior

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Spherical RGPs are good for?

a) High corneal cyl and low refractive cyl
b) High corneal cyl and high refractive cyl
c) Low to medium corneal cyl and low to medium refractive cyl (same axis)
d) Low to medium corneal cyl and high refractive cyl

A

Low to medium corneal cyl and low to medium refractive cyl (same axis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Why are spherical RGPs not good for fitting eyes with low corneal cyl and high refractive astigmatism?

A

because the tear layer formed is insufficient to correct the refractive astigmatism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Why are spherical RGPs not good for fitting eyes with high corneal cyl and high refractive cyl?

A

the tear layer power formed would correct the refractive astigmatism however the spherical RGP would not fit the toric corneal shape well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Why are spherical RGPs not good for fitting eyes with high corneal cyl and low refractive cyl?

A

the tear layer power formed would over-correct the refractive astigmatism and the spherical RGP would not fit the toric cornea shape well - this is the LEAST DESIRABLE OPTION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What RGP parameters MUST you have to order a spherical RGP?

A 
diameter
optic zone diameter
BC
BVP
RGP design
material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

The diameter of a RGP should be how many millimeters smaller than the cornea?

A

2-2.5mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

An RGP that fits within the lids is called?

A

intra-palpebral fitting (usually small diameter lenses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

An RGP that stays more or less in the middle of the cornea and between the lids is called?

A

inter-palpebral fitting (usually medium diameter lenses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

An RGP that stays tucked under the upper eyelid and moves with the upper lid during blinking is called?

A

lid attachment fitting (usually large diameter lenses with respect to aperture size)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

For a steep cornea (>47D) what lens diameter size would you choose?

A

small/medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

For a flat cornea (<39D) what lens diameter size would you choose?

A

Med/large to large

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

A small diameter RGP is classified as?

A

<9.00mm (7.0 OZD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

A small/medium diameter RGP is classified as?

A

~9.0-9.3mm (7.5 OZD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

A medium/large diameter RGP is classified as?

A

~9.5-9.8mm (8.0 OZD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

A large diameter RGP is classified as?

A

> 9.8mm (8.5 OZD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

When fitting a spherical RGP what are the parameters to select in order? (5)

A
  1. Diameter of lens
  2. Base curve
  3. BVP
  4. Lens design
  5. Test lens on eye
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

How thick should the channel of tears be through the central portion of a RGP?

A

10-20um

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

a 0.1mm change in radius is equivalent to how much dioptric change?

A

0.5D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

When there is moderate astigmatism what BC do you select for a spherical RGP?

A

slightly steeper than flat K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What is the ideal axial edge lift?

A

120um

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What does this mean:

7.85:7.6/8.50:8.2/11.0:9.0

A
  1. 85BC and 7.6 OZD
  2. 50 secondary curve and 8.2 diameter
  3. 0 peripheral curve and 9.0 diameter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Peripheral curve design - tangent designs uses the tangent cone concept and involves?

A

landing of midperiphery to allow even distribution of pressure and limit lens lateral drift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Dynamic fitting characteristics looks at?

A

how the lens acts naturally on the eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Static fitting characteristics shows the?

A

lens-to-cornea curvature relationship

60
Q

What is the minimum threshold needed in order to judge the presence of fluoroscein?

A

20um

61
Q

The optimum edge width is?

A

0.5mm

62
Q

A RGP should decentre less than how many mm?

A

0.5mm

63
Q

A RGP can be graded as flat and loose. The level of looseness is graded considering? The level of flatness is graded by the?

A

dynamic fitting characteristics

static fitting characteristics

64
Q

Most loot fitting RGPs are caused by?

A

BOZR too much flatter than corneal curvature

65
Q

Loose lenses can also be due to fitting ____ lenses without a ___ BC component

A

small

flat

66
Q

A lens that shows excessive central pooling, heavy mid-peripheral contact , narrow edge lift and width is?

A

steep and tight fitting lens

67
Q

a slightly loose or tight RGP should have its BC changed by?

A

0.15mm

68
Q

A visibly loose/tight RGP should have its BC changed by?

A

0.2-0.3mm

69
Q

Very loose/right RGP should have its BC changed by?

A

0.4mm

70
Q

An excessively loose RGP should have its BC changed by?

A

0.5mm

71
Q

tight fitting lenses are most commonly caused by?

A

BOZR too much steeper than corneal curvature

72
Q

Tight fitting RGPs can also occur when a lens fitting is too _____ leading to lens vaulting

A

large

73
Q

What is wrong with a RGP if you see the following characteristics?

  • typically ride centrally or low
  • move quickly on blink
  • vault over the central cornea too much
  • produce bubbles in the central zone
  • impinge on the peripheral cornea
A

BC too steep

74
Q

What is wrong with a RGP if you see the following?

  • typically ride high but eventually slip off to the side or downward
  • float around on the eye
  • have large excursions or hang beneath the lid
  • have too much edge lift
A

BC too flat

75
Q

What is wrong with a RGP if you see the following?

  • irregular pressure over the cornea
  • movement shows the lens to rock up and down or rock left and right
A

cornea too astigmatic

76
Q

a lens movement that rocks up and down is associated with what sort of astigmatism?

A

with the rule

77
Q

What is wrong with a RGP if it has the following characteristics?

  • typically move freely on the eye or decentre easily
  • may dislodge onto conj or pop off the eye with quick lateral gazes
A

diameter too small

78
Q

Bigger lenses are naturally looser/tighter because of lower/higher sagittal height

A

tighter

higher

79
Q

Smaller lenses are naturally looser/tighter because of lower/higher sagittal height

A

looser

lower

80
Q

What is wrong with a RGP with the following characteristics?

  • excessive lens tightness
  • restrict movement
  • limit tear exchange
  • can irritate limbal area = excessive tearing and lens awareness
A

lens too big

81
Q

If a lens is made 0.5mm larger then the BC should be made how much flatter/steeper? (unless you want central clearance to change)

A

0.05mm flatter (0.25D)

82
Q

What effect does increasing TD have on edge lift?

A

increases edge lift

83
Q

What two things does a high edge lift cause?

A

causes lens to ride higher

produces more lid attachment

84
Q

Reducing TD has what effect on edge lift?

A

decreases edge lift

85
Q

What two things does a low edge lift cause?

A

causes lens to ride lower

less lid attachment

86
Q

To increase edge lift, what parameters can you increase? (5)

A 
SCR (most influential)
PCR
SCW (while reducing OZD)
PCW (while reducing OZD)
TD along with OZD
87
Q

High plus powered RGPs have possible problems with inferior decentration. This can be managed through?

A

adding a minus carrier on the edge

88
Q

High minus powered RGPs can have possible problems with lid interactions. This can be managed through?

A

adding a plus lenticular - resulting in wedge shape

89
Q

What edge configuration has the best comfort level?

A

centre>posterior>anterior

90
Q

Wettability is measured with what three methods

A

sessile drop
Wilhelmy plate
captive bubble

91
Q

Dk denotes the ______ of contact lens materials

A

permeability

92
Q

Dk/t denotes what?

A

the transmissibility through a lens of given thickness

93
Q

What lens parameters can you change for a lens that is too tight? (4)

A

increase BC
increase peripheral curve (edge lift)
widen peripheral curve
decrease OZD

94
Q

What lens parameters can you change for a lens that is too loose? (4)

A

decrease BC
decrease peripheral curve (edge left)
reduce peripheral curve width
increase OZD (with TD)

95
Q

Dimple veiling is caused if the lens is? (2)

A

steep centrally

too much edge lift

96
Q

Constant high or low riding RGPs can lead to?

A

mechanically induced corneal warpage/moulding

97
Q

The underlying associated cause of corneal warpage is?

A

prolonged oedema

98
Q

What is often the cause of staining at 3 and 9o’clock?

A

lens edge miniscus causing local tear film thinning

99
Q

What is characterised by an opaque, elevated mass at the nasal and/or temporal cornea adjacent the limbus

A

vascularised limbal keratitis

100
Q

What is the etiology of blink related problems with a RGP?

A

lens edge awareness
sensation of any surface irregularity
excessive lens movement

101
Q

The upper lid being subjected to higher frictional forces of intrinsic or extrinsic nature causes what?

A

lid-wiper epitheliopathy

102
Q

Toric RGPs are used in what two situations?

A

to improve fitting on regular astigmatic cornea

to correct residual astigmatism that occurs when fitting spherical RGP

103
Q

Calculated residual astigmatism (CRA) = ?

A

spectacle cyl - corneal cyl

104
Q

What makes residual astigmatism significant?

A

> 0.75DC
Oblique when not corrected > ATR > WTR
large pupils with ATR astig
if the Px is habitually fully corrected with cyl

105
Q

Bitoric and back-surface toric CLs are used to fit corneas with a minimum how many dioptres of regular astigmatism?

A

2D

106
Q

How do you choose the BCs for a back toric RGP?

A

select BC equal to flat K for r1

select BC 0.1mm flatter than steep K for r2 (note -0.50 tear layer)

107
Q

Bennet’s tricurve design SCR and PCR parameters?

A

SCR add 1.0-1.5mm to BC/0.3 wide

PCR add 1.5-2.0mm to SC/0.4 wide

108
Q

The induced over-correction is a minus cylinder at the same axis as the _______ principle meridian. The magnitude is proportional to the degree of ________ and reractive index of ________

A

flatter
CL toricity
CL material

109
Q

Back surface torics work for a patient that has refractive cylinder that is _____ greater than the corneal cylinder

A

30-50%

110
Q

Back surface toric ΔBVP (dioptres) =

A

ΔBC (dioptres) * material factor

111
Q

What RGP works well with patients who have spectacle cyl = corneal cyl

A

SPE back toric RGP

112
Q

Rotation of what toric RGP does NOT induce unwanted astigmatism?

A

SPE back toric

113
Q

Sterilisation results in

A

all viable microbes to be eliminated; none can reproduce

114
Q

Disinfection results in

A

substantial reduction in level of microbial contamination

115
Q

The D-value of a solution is an index for what? Is a lower or higher D-value better?

A

index of disinfection rate

lower is better

116
Q

Complete disinfection requires pressure of ____kPa applied to steam and temperature of _____ degrees and after _____ mins all bacteria, spores, fungi, and viruses killed

A

100
121
120

117
Q

Name three buffers used in soft lens solutions

A

sod phosphate
sod borate
sod bicarbonate

118
Q

Methyl cellulose is what kind of agent and what does it do?

A

viscosity agent

improve wetting time + comfort

119
Q

Chelating agents e.g. sodium adetate have what function?

A

enhances actions of preservatives

120
Q

You cannot use SCLs with what 3 eye drops?

A

Lomide
Naphcon-A
Latanoprost

121
Q

Hydrogen peroxide systems aren’t as good against which type of microbe?

A

acanthamoeba

122
Q

PVA, PVP and PEG are all examples of what?

A

wetting agents

123
Q

BAK, PHX, CHX are examples of what ind of agents?

A

RGP solution preservatives

124
Q

What are the top RGP troubleshooting tips?

A

Polishing 6-12 monthly
Progent protein cleaner
AO Sept, omnicare

125
Q

What lens is used when a normal spherical RGP gives good vision but uneven edge lift on a toric cornea

A

TSP

126
Q

Adding what component to a lens makes it ionic?

A

methacrylic acid (MA)

127
Q

An ionic lens causes what two things?

A

attracts more lysozyme but

makes material more wettable

128
Q

FDA 1

A

low water + non-ionic

129
Q

FDA 2

A

high water + non-ionic

130
Q

FDA 3

A

low water + ionic

131
Q

FDA 4

A

high water + ionic

132
Q

higher water content of SCL usually correlates with

A

higher Dk/t (except SiHi)

133
Q

How much O2 is needed to prevent oedema for DW and EW SCLs?

A
  1. 9% (Dk/t = 24) for DW

17. 9% (Dk/t = 87) for EW

134
Q

Thin or thick SCLs interact more with the lids and move more?

A

thick

135
Q

What effect does increasing water content do to lens movement?

A

decreases lens movement

136
Q

The Da Vinci Code helped understand what concept?

A

corneal neutralisation in a bowl of water

137
Q

Rene Descartes is known for what concept?

A

elongated fluid-filled tube to enlarge retinal image size

138
Q

1946 Kevin Tuohy did what?

A

discovered first corneal lens

139
Q

Dry eye etiologies with contact lenses? (3)

A
  1. Dessication secondary to pervaporation (SCL)
  2. Dessication secondary to exposure/poor tear consistency over cornea (RGP)
  3. Bioincompatibility leading to tear instability
140
Q

The lipid layer of the tear film has two phases which are? (2)

A

non-polar phase

polar phase

141
Q

What is the function of the outermost layer of the lipid layer?

A

regulate transmission water rate, CO2, O2, ions

142
Q

What is the function of the inner layer of the lipid layer?

A

provide enhanced stability

143
Q

Which lipid layer is abundant in short chain saturated fatty acids?

A

polar phase

144
Q

Which FDA group material is the most lipid binding?

Which one has the least?

A

FDA group II materials (high water, non-ionic)

FDA group III

145
Q

Local dry spots are caused by hydroph____ areas

A

hydrophobic

146
Q

Proteins deposit on what FDA group material which makes surface less hydrophilic which then attracts lipids

A

FDA group IV

147
Q

What is the first step of management for lipid deposition on CLs?

A

select different material for Px

OPTOM 430 Test (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions