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Contact Lenses > indications for CLs, slit lamp use in practice, record keeping and staining > Flashcards

indications for CLs, slit lamp use in practice, record keeping and staining Flashcards

0
Q

Name the two materials of two types of RGP contact lenses

A
  1. Polymethylmethacrylate (PPMA)

2. (Rigid) gas permeable (R)GP

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1
Q

List the 4 different types of contact lenses

A
  1. Rigid gas permeable (RGP)
  2. Soft
  3. Hybrids
  4. Silicone rubber (SRCL)
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2
Q

List the sizes of RGP lenses

A
  • smaller than corneal diameter (+/- 9.5mm)
  • semi-scleral (+/- 14mm)
  • scleral (+/- 18mm)
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3
Q

What was the first hard contact lens material

A

PPMA

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4
Q

Since when were PPMA lenses made

A

1946

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5
Q

What is a disadvantage of PPMA

A

Difficult to fit

& allows 0% of oxygen through the lens

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6
Q

What is the advantage of rigid gas permeable lenses over PPMA

A

RGP lenses allows oxygen to go through the lens

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7
Q

How does the cornea get oxygen when using an RGP lens

A

Behind the lens, so the cornea will take oxygen from the tears

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8
Q

Name the two different material types of soft contact lenses

A
  1. Hydrogel

2. Silicone hydrogel

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9
Q

What is the disadvantage of hydrogel lenses

A

Can get dry at the end of the day and then can lose its shape

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10
Q

What type of material is a hydrogel lens

A

Hydrophilic

With different water contents (amount of water in them)

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11
Q

What is silicone hydrogel lenses a mixture of

A

Silicone rubber
&
Hydrophilic materials

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12
Q

What does silicone hydrogel lenses contain a high amount of

A

Oxygen

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13
Q

What category of lenses are silicone hydrogel

A

Extended wear

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14
Q

What is the purpose of extended wear contact lenses

A

Can be worn over night

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15
Q

What size is soft lenses

A

Larger than corneal diameter (+/- 14mm)

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16
Q

Describe the material of hybrid contact lenses

A

Rigid centre
&
Soft skirt attached

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17
Q

Why do hybrid lenses have a rigid centre

A

Provides good vision like an RGP lens

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18
Q

Why do hybrid lenses have a soft skirt attached

A

Provides comfort like a soft CL

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19
Q

What type of lens is a silicone rubber (SRCL)

A

Hydrophobic (made hydrophilic)

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20
Q

What size is the silicone rubber SRCL

A

Lombok size

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21
Q

What is a silicone rubber SRCL extremely high in

A

Oxygen permeability

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22
Q

What is silicone rubber SRCL mainly used for

A

Therapeutic use only

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23
Q

Name some therapeutic uses of silicone rubber SRCL

A
  • aphakia
  • corneal irregularities
  • dry eyes
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24
Q

list the motivations for using contact lenses

A
  • cosmetic
  • convenience
  • refractive, pathological
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26
Q

list 5 indications for using contact lenses

A
  • refractive
  • cosmetic (plano colour)
  • sports (head contact, fast movement, but avoid RGP lenses)
  • occupational (armed forces, sports, entertainment industry)
  • pathological
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27
Q

explain 4 refractive indications for the use of contact lenses and myopia

A
  • improved acuity
  • greater FoV
  • normal eye size
  • myopia is controlled
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28
Q

explain 3 refractive indications for the use of contact lenses and hyperopia

A
  • greater FoV
  • normal eye size
  • possibility of reduced acuity
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29
Q

why is there a possibility of reduced acuity for a hyperope who wears contact lenses (give 2 reasons)

A
  • less mag with contact lenses

- can control accommodation with specs

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29
Q

explain the refractive indication for contact lenses and anisometropia

A
  • uniocular (RE plano LE -6.00DS) or binocular (RE -2.00DS LE -14.00DS) is more visually comfortable
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30
Q

explain 3 refractive indications for the use of contact lenses and astigmatism

A
  • greater success in myopic eyes

- greater success if DC

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31
Q

explain the refractive indication for contact lenses and binocular vision problems

A

only vertical prism in 1 eye possible

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33
Q

list the pathological indications for contact lenses (list 8)

A
  • cranio-facial anomalies
  • allergies
  • irregular cornea
  • keratoconus
  • aphakia
  • bandage
  • protection
  • cosmetic (so both eyes look the same e.g. a coloured contact lens)
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34
Q

list the 4 contra-indications of contact lenses and occupation

A
  • dust
  • chemical vapours
  • PC use
  • poor ventilation
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35
Q

list the 3 contra-indications of contact lenses and allergies

A
  • hayfever
  • eczema
  • sinusitis
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36
Q

list the 4 contra-indications of contact lenses and poor hygiene

A
  • regular onset of conjunctivitis
  • blepharitis
  • herpes zoster
  • smoker
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37
Q

list the 3 contra-indications of contact lenses and ill health - implications on tear film quality

A
  • DM
  • hyper or hypothyroidism
  • arthritis
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38
Q

list the 3 contra-indications of contact lenses and age - ability to handle contact lenses

A
  • infant
  • student
  • presbyope
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39
Q

list 5 choices for choosing RGP lenses

A
  • vision (is better)
  • corneal irregularity
  • dry eyes
  • compliance
  • SCL failure
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40
Q

list 3 choices for choosing SCL

A
  • infrequent wear
  • environment
  • RGP failure inc fitting problems
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41
Q

list the 2 reasons for slit lamp use and contact lenses

A
  1. CL fitting
    - baseline measurements
  2. aftercare
    - lens fit
    - surface condition
    - ocular integrity
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42
Q

list the 3 levels of magnification required on a slit lamp in relation to contact lenses

A
  • general eye - low 6-10x
  • structures - medium 16x
  • detail - high 25-40x
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43
Q

explain the 4 observations of slit lamp use in CL practice on a low mag for general eye

A
  • lids/lashes
  • cornea
  • conjunctiva
  • sclera
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44
Q

explain the 4 observations of slit lamp use in CL practice on a medium mag for structures

A
  • blepharitis
  • meibomian gland dysfunction
  • concretions
  • corneal staining
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44
Q

state the severity of stromal oedema of 0-5%

A

safe

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45
Q

explain the 3 observations of slit lamp use in CL practice on a high mag for details

A
  • epithelial changes (any staining)
  • stromal striae and folds (in stroma)
  • endothelial folds, blebs (of missing endothelium) and polymegathism
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46
Q

state the severity of stromal oedema of 5-10%

A

caution

47
Q

state the severity of stromal oedema of 10-15%

A

danger

48
Q

state the severity of stromal oedema of 15-20%

A

pathological (loss of transparency & loss of vision)

49
Q

which filter excites flourescein

A

cobalt blue

50
Q

what is the green (red-free) filter used for

A

enhances contrast of blood vessels and rose bengal staining

51
Q

what is the neutral density filter used for

A

reduces beam brightness, increases patient comfort

52
Q

what is the round glass filter used for

A

diffuses beam to give broad unfocused illumination

53
Q

what is the polarising filter used for

A

reduces specular reflections when used in crossed pairs

54
Q

what does flourescein do

A

highlights epithelial defects as it stains areas of missing cells

55
Q

how long does the flourescein dye last for

A

2-4 minutes

57
Q

which other filter is used with flourescein to enhance staining/improve contrast

A

yellow (wratten 12)

57
Q

what does lissamine green stain

A

dead and degenerative cells

58
Q

name the stain which allows to see more staining than flourescein

A

lissamine green

59
Q

how much discomfort is there with lissamine green

A

little

60
Q

how long is optimal staining of lissamine green

A

1-4 minutes

61
Q

which intensity of illumination should lissamine green be used with

A

low

62
Q

which filter is used to enhance the lissamine green staining

A

Red (wratten 25)

63
Q

what does rose bengal stain

A

dead cells and those unprotected by intact mucin layer

64
Q

what is rose bengal used to investigate

A

dry eye

65
Q

what sensation does rose bengal staining cause

A

stinging

66
Q

what does rose bengal show in the eye

A

high areas of toxicity in eye

67
Q

what is direct illumination of slit lamp in relation to the beam

A

within the beam

68
Q

what is indirect illumination of slit lamp in relation to the beam

A

outside the beam

69
Q

what is diffuse used for

A

general overview, see whole of CL

70
Q

what is parallelepiped used for

A

scan the cornea, conjunctiva and CL

71
Q

what is optic section used for

A

assess depth (increase mag)

72
Q

what is specular reflection used for

A

assess tear film (horizontal beam) and endothelium (high mag)

73
Q

what is retro illumination used for

A

back light from iris or fundus

74
Q

where are micro cysts and vacuoles found

A

epithelial layer of cornea (intra epithelial)

75
Q

which slit lamp technique is used to observe micro cysts and vacuoles

A

retro illumination

76
Q

what are vacuoles and micro cysts

A

small bubbles in the front surface of the epithelium

77
Q

what is a description of a vacuole

A

cyst like inclusions

78
Q

what are vacuoles filled with

A

gas or fluid

79
Q

what are microcysts a distinctive and easily detectable indicator of

A

contact lens induced hypoxia

80
Q

what are micro cysts filled with

A

dead cell material

81
Q

explain the unreversed effect

A

if light is shone from the right, the shadow is on the left and structure is on the left

82
Q

which structure uses the unreversed effect

A

vacuole

83
Q

what is the reason behind the unreversed effect

A

there is a lower refractive index of material (gas or fluid) that sits in the vacuole

84
Q

explain the reversed effect

A

if light is shone from the right, the shadow is on the right and structure is on the left

85
Q

which structure uses the reversed effect

A

microcyst

86
Q

what is the reason behind the reversed effect

A

there is a higher refractive index of material (dead cell material) in the microcyst

87
Q

what is a slit lamp routine CL fit used to observe

A
  • tear film
  • lid margin inferior & superior (for meibomian gland dysfunction)
  • lashes inferior & superior
  • palpebral conjunctiva inferior & superior
  • bulbar conjunctiva 4 segments (ISNT)
  • cornea 5 segments (CISNT) c=central
88
Q

state the slit lamp routine 1

A

start with white light
general look at ocular adnexa
- diffuse, low mag, whole eye at once
- sclerotic scatter, low mag, ALERTS!

increase mag, parallelepiped scan for

  • lashes and lid margins
  • tear prism height and continuity
  • conjunctiva
  • cornea: swing nasal-temp and back, two times. check whole cornea

change to optic section on high mag to assess depth of anything unusual
while scanning cornea view direct and indirect
investigate limbus separately

89
Q

state the slit lamp routine 2

A 
then use blue light and flourescein 
- TBUT - timing, position 
- tear prism - height and regularity 
- lid margin 
- staining 
conjunctiva 4 segments &
cornea - location, depth & extent
90
Q

state the slit lamp routine 3

A 
back to white light 
- lower lid eversion 
- meibomian glands 
push & squeeze 
- upper lid eversion 
white light - hyperaemia 
blue light - roughness/papillae
91
Q

state the slit lamp routine 4

A

lens fit and condition
- diffuse for centration and movement of lens
- direct for fit and surface condition
dryness, broken/chipped, deposits

92
Q

what are the advantages of real life photos of clinical grading

A

they are real eyes so can see a real life image

93
Q

what are the disadvantages of real life photos of clinical grading

A
  • different patients in different pictures

- some pictures have different illuminations for the same problem

94
Q

what are the advantages of the animated pictures of clinical grading

A

it is the same eye so no variance

95
Q

what are the disadvantages of animated pictures of clinical grading

A

cannot relate to real patient

97
Q

list the 3 reasons of a legal document

A
  • accurate recording of presenting signs and symptoms
  • respond to complaints
  • proof that standard of care was met (if not written, it was not done)
97
Q

what is the advantage and reason for using standardised grading scale

A

uses common language and reduces intra/inter observer variability

98
Q

list 5 reasons why record keeping is very important

A
  • monitoring progression
  • record across time, within and between practitioners
  • impact new therapies or management
  • medico-legal requirements
  • patient communications
99
Q

what is the severity of grade 0

A

normal

100
Q

what is the clinical interpretation of grade 0

A

no action required

101
Q

what is the severity of grade 1

A

trace

102
Q

what is the clinical interpretation of grade 1

A

action rarely required

103
Q

what is the severity of grade 2

A

mild

104
Q

what is the clinical interpretation of grade 2

A

action possibly required

105
Q

what is the severity of grade 3

A

moderate

106
Q

what is the clinical interpretation of grade 3

A

action usually required

107
Q

what is the severity of grade 4

A

severe

108
Q

what is the clinical interpretation of grade 4

A

action required

109
Q

what are the corneal staining rules

A
  • chose a scale and stick with it
  • always write which scale you used
  • don’t guess the scale, look it up
    grade ~/>1 = clinically significant
    grade ~/>3 = requires management plan
110
Q

corneal staining is…

A
  • clinically insignificant in 60% of CL wearers
  • often asymptomatic (i.e. severity signs not related to symptoms)
  • in 35% of non CL wearers due to incomplete blink or closure
111
Q

what type of corneal staining is ‘smile’

A

desiccation

112
Q

what type of staining is ‘linear’

A

foreign body

113
Q

what type of staining is ‘SEAL’

A

mechanical

114
Q

what type of staining is 3&9

A

desiccation

115
Q

what type of staining is diffuse

A

toxicity

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