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Contact Lens Theory > Final Exam Revision > Flashcards

Final Exam Revision Flashcards

1
Q

What 4 things can we do to improve a loose fitting lens?

A
  • Select a larger total diameter.
  • Select a steeper radius.
  • Use a more rigid or lower water content material.
  • Use a different lens thickness.
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2
Q

What 4 things can we do to improve a tight fitting lens?

A
  • Select a flatter radius.
  • Select a smaller total diameter.
  • Use a less rigid or higher water content material.
  • Use a different lens thickness.
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3
Q

Where does the lipid layer of the tears (outermost layer) get produced from?

A

Meibomian glands

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4
Q

What is the primary function of the lipid layer of tears?

A

to prevent evaporatioon

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5
Q

Where does the aqueous layer of the tears (middle layer) get produced from?

A

lacrimal glands

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6
Q

What is the primary function of the aqueous layer of tears?

A

provide nutrients to eye

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7
Q

Where does the mucin layer of the tears (innermost layer) get produced from?

A

goblet cells in the conjucntiva

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8
Q

What is the primary function of the mucin layer of tears?

A

to adhere the tear to the eyes

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9
Q

The K readings have 2 or more difference between them. What kind of lens should we consider/do?

A

RGP

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10
Q

How is wettability best described?

A

Ability of a drop of liquid to SPREAD over a surface

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11
Q

A keratometer is primarily used to measure……..

A

the central corneal curvature

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12
Q

For observing aqueous flare, which illumination should be used?

A

conical beam

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13
Q

What is the purpose of diffuse illumination?

A

for a general look at the ocular tissues and lids under low magnification

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14
Q

Identify the three types of direct focal illuminations

A

Conical Beam
Parrellapiped
Optic section

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15
Q

Which illumination method is best for examining Descmet’s membrane deposits and corneal blood vessels?

A

Specular reflection

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16
Q

Which 3 illuminations are set ‘out of click’?

A

Sclerotic scatter
Indirect Retro Illumination
Indirect Proximal Illumination

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16
Q

Sterile water can be used to rinse both soft and gas permeable lenses. T/F

A

FALSE

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16
Q

What are 4 uses for saline solution?

A

Heat disinfection
rinsing lenses prior to insertion
ocular irrigation
wetting fluorescein strips

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17
Q

Soft lens in situ refers to a lens that………

A

is on the cornea

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18
Q

Tear break up time is assessed using………

A

fluorescein

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19
Q

When removing an RGP lens, the patient should be asked to look…………

A

Up

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20
Q

Contact lenses benefit pxs with refractive anisometropia. T/F

A

TRUE

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21
Q

If a px requires correction for near vision only this is a contrindication for cl use. T/F

A

TRUE

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22
Q

A visual contraindication for cls is……..(prism related)

A

prism required horizontally or more than 3 prism vertically

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23
Name on situation where cls should not be dispensed to a non-compliant px?
poor general hygiene
24
What is a disadvantage of silicone hydrogel lenses?
more liable to lipid deposits
25
Given a rx of OD:-2.75 and OS: -3.00 with horizontal and vertical keratometers both at 180/090, what is the first option for cls?
soft spherical lens OU
26
Given a rx of OD:-2.75/-1.75 x 180 and OS: -3.00/-1.75 x 180 with horizontal and vertical keratometers both at 180/090, what is the first option for cls?
soft toric lens OU
27
One disadvantage of RGP lenses is: 1-not being able to correct corneal astigmatism 2-difficult to maintain 3-not able to modify 4-3 and 9 o'clock staining
2-difficult to maintain
28
When observing a client's blinking during a cls exam, what is important?
completeness of blink
29
Which symptoms indicate marginal dry eye? 10 (name a couple)
burning itching foreign body sensation sore tiredness grittiness dryness photophobia irritation lid heaviness
30
For marginally dry eyes, the best type of lens to use is........
a lower water content
30
Reduced height of tear prism indicates a reduced tear volume. T/F
TRUE
31
Advantages of low water content lenses include: 3
-better reproducibility -less dehydration on the eye -great tensile strength
32
Advantages of high water content lenses include: 3
-Better comfort because of material softness -can be made thinner -longer life span
33
One of the main reasons for the clinical success or failure of a particular lens is:
lens dehydration
34
Desides DK value, which factors affect comfort, vision, and lifespan? 6
-fitting method -lens design -mechanical stability -manufacturing technique -optical quality -surface wetting qualities
35
Which type of lens is used as a therapeutic lens?
bandage lens
36
Silicone hydorgel lenses have a high DK value. T/F
TRUE
37
Why is peripheral clearance important in an RGP lens design? 1- allows the lens to be designed as a spherical, aspheric or a combination of both 2-allows the transition between the central portion and the periphery to be sharp 3- Allows for adequate tear exchange 4-stabilizes lens so it does not fall out
3- Allows for adequate tear exchange
38
A gas permeable lens that fits too flat will result in.......... 2 (relation to movement)
less attraction and stability
39
The most commonly accepted method of rigid lens fitting is...............
alignment method (central, not steep, not flat)
40
Base curve selection of the trial lens in rigid lens fitting is based on.............
K readings
41
The colbalt blue filter in a slit lamp exam is used to:
enhance contrast when looking at fluorescein
42
A hydrophilic lens material is........
water loving
43
Which manufacturing method involves using a liquid monomer?
spin-casting
44
How can a small chip on the edge of the lens also be described as?
small piece of lens material missing from lens edge
45
A condition caused by insufficient oxygen to the cornea is?
Corneal Edema
46
What is the back surface radius of a cls also known as?
back optic zone radius
47
Reflex tears on the lens surface may ......... 1-pose a problem when trying to insert the lens 2-improve the lens fit 3-not affect the lens at all 4-always mean the lens is defective
1- pose a problem when trying to insert the lens
48
What are 3 ways we can evaluate the fit of a cls?
the lens centration the lens movement the lens rotation
49
Cls can be used to correct astigmatism. T/F
TRUE
50
A lens that shows too much movement is likely to be.............
a flat/loose fitting lens
51
A good movement range for a soft cls during a blink is............
0.5mm
52
Excessive movement of a cls can lead to discomfort. T/F
TRUE
53
A lens that is inverted (inside out) when placed on the eye will cause discomfort. T/F
TRUE
54
A cls that rides too low on the eye is considered........
a flat lens
55
The mnemonic 'LEFT ADD RIGHT SUBTRACT' is used for:
compensating for lens rotation
56
When a contact lens rotates to the left, you should............
add the rotation to the cylinder axis
57
If the lens has poort wettability what might be seen in the keratometer?
distorted mires
58
Which type of astigmatism is more difficult to fit due to sideways decentration?
ATR
59
When the lens on the eye changes in Base Curve, what is this called?
Flexure
60
When a rigid lens is hydrated does it become flatter or steeper?
Flatter
61
Name 3 advantages of rigid lenses.
-increased corneal O2 -reduced risk of microbial keratitis and allergy -superior vision for px with corneal astig
62
What is the main method of cls manufacture?
cast molding
63
What does hydrophobic mean?
Water hating
64
What allows for adequate tear exchange in an RGP? 2
Peripheral clearance Fenestration
65
What is the best illumination to use if you suspect the patient may have protein in their aqueous?
conical beam
66
What solution is toxic to the eye prior to neutralization?
Hydrogen Peroxide
67
Name 5 types of therapeutic lenses.
Bandage Myopia control OrthoK Scleral Drug Delivery
68
What type of dry eye staining is usually related to RGP wear?
3 and 9 o'clock
69
What does SEAL stand for?
Superior epithelial arcuate lesion

Contact Lens Theory (27 decks)

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