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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
Q

Name on situation where cls should not be dispensed to a non-compliant px?

A

poor general hygiene

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24
Q

What is a disadvantage of silicone hydrogel lenses?

A

more liable to lipid deposits

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25
Q

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?

A

soft spherical lens OU

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26
Q

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?

A

soft toric lens OU

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27
Q

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

A

2-difficult to maintain

28
Q

When observing a client’s blinking during a cls exam, what is important?

A

completeness of blink

29
Q

Which symptoms indicate marginal dry eye? 10 (name a couple)

A

burning
itching
foreign body sensation
sore
tiredness
grittiness
dryness
photophobia
irritation
lid heaviness

30
Q

For marginally dry eyes, the best type of lens to use is……..

A

a lower water content

30
Q

Reduced height of tear prism indicates a reduced tear volume. T/F

A

TRUE

31
Q

Advantages of low water content lenses include: 3

A

-better reproducibility
-less dehydration on the eye
-great tensile strength

32
Q

Advantages of high water content lenses include: 3

A

-Better comfort because of material softness
-can be made thinner
-longer life span

33
Q

One of the main reasons for the clinical success or failure of a particular lens is:

A

lens dehydration

34
Q

Desides DK value, which factors affect comfort, vision, and lifespan? 6

A

-fitting method
-lens design
-mechanical stability
-manufacturing technique
-optical quality
-surface wetting qualities

35
Q

Which type of lens is used as a therapeutic lens?

A

bandage lens

36
Q

Silicone hydorgel lenses have a high DK value. T/F

A

TRUE

37
Q

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

A

3- Allows for adequate tear exchange

38
Q

A gas permeable lens that fits too flat will result in………. 2 (relation to movement)

A

less attraction and stability

39
Q

The most commonly accepted method of rigid lens fitting is……………

A

alignment method (central, not steep, not flat)

40
Q

Base curve selection of the trial lens in rigid lens fitting is based on………….

A

K readings

41
Q

The colbalt blue filter in a slit lamp exam is used to:

A

enhance contrast when looking at fluorescein

42
Q

A hydrophilic lens material is……..

A

water loving

43
Q

Which manufacturing method involves using a liquid monomer?

A

spin-casting

44
Q

How can a small chip on the edge of the lens also be described as?

A

small piece of lens material missing from lens edge

45
Q

A condition caused by insufficient oxygen to the cornea is?

A

Corneal Edema

46
Q

What is the back surface radius of a cls also known as?

A

back optic zone radius

47
Q

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

A

1- pose a problem when trying to insert the lens

48
Q

What are 3 ways we can evaluate the fit of a cls?

A

the lens centration
the lens movement
the lens rotation

49
Q

Cls can be used to correct astigmatism. T/F

A

TRUE

50
Q

A lens that shows too much movement is likely to be………….

A

a flat/loose fitting lens

51
Q

A good movement range for a soft cls during a blink is…………

A

0.5mm

52
Q

Excessive movement of a cls can lead to discomfort. T/F

A

TRUE

53
Q

A lens that is inverted (inside out) when placed on the eye will cause discomfort. T/F

A

TRUE

54
Q

A cls that rides too low on the eye is considered……..

A

a flat lens

55
Q

The mnemonic ‘LEFT ADD RIGHT SUBTRACT’ is used for:

A

compensating for lens rotation

56
Q

When a contact lens rotates to the left, you should…………

A

add the rotation to the cylinder axis

57
Q

If the lens has poort wettability what might be seen in the keratometer?

A

distorted mires

58
Q

Which type of astigmatism is more difficult to fit due to sideways decentration?

A

ATR

59
Q

When the lens on the eye changes in Base Curve, what is this called?

A

Flexure

60
Q

When a rigid lens is hydrated does it become flatter or steeper?

A

Flatter

61
Q

Name 3 advantages of rigid lenses.

A

-increased corneal O2
-reduced risk of microbial keratitis and allergy
-superior vision for px with corneal astig

62
Q

What is the main method of cls manufacture?

A

cast molding

63
Q

What does hydrophobic mean?

A

Water hating

64
Q

What allows for adequate tear exchange in an RGP? 2

A

Peripheral clearance
Fenestration

65
Q

What is the best illumination to use if you suspect the patient may have protein in their aqueous?

A

conical beam

66
Q

What solution is toxic to the eye prior to neutralization?

A

Hydrogen Peroxide

67
Q

Name 5 types of therapeutic lenses.

A

Bandage
Myopia control
OrthoK
Scleral
Drug Delivery

68
Q

What type of dry eye staining is usually related to RGP wear?

A

3 and 9 o’clock

69
Q

What does SEAL stand for?

A

Superior epithelial arcuate lesion

Contact Lens Theory (27 decks)

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