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Optics II block 5 > Tear Film Optics > Flashcards

Tear Film Optics Flashcards

1
Q

In this mindset, people believe their basic qualities like their intelligence or talent are simply fixed traits.
Spend time documenting. Intelligence and talent instead of developing them
Believe that talent alone creates success

A

Fixed mindset

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2
Q

In this mindset, people believe that they most basic abilities can be developed through dedication and hard work, brains and talent are just the starting point
Creates a love of learning and resilience that is essential for great accomplishments

A

Growth mindsets

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3
Q

What is optometrys foundation and core professional service?

A

Correcting poor vision caused by imperfections in the eyes optical system

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4
Q

What is the profession of optometry distinguished by?

A
  • expert knowledge of optics, especially optics of the eye

- a concern for visual problems, most of which have optical causes

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5
Q

What are all the areas of optics of the eye

A
  • tear film
  • corneal
  • crystalline lens
  • pupillary
  • axes of the human eye and its angles
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6
Q

What are the layers of the cornea?

A
  • epithelium
  • bowmans membrane
  • stroma
  • descemet’s membrane
  • endothelium
  • Duas layer
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7
Q

Protects the cornea by providing a barrier against water, larger molecules and toxic substances

A

Epithelium

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8
Q

Consists mainly of randomly arranged collagen fibrils

A

Bowmans membrane

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9
Q

Comprises 90% of corneal thickness, and over 200 collagen lamellar. Collagen fibrils within each lamella run parallel to each other and the successive lamellar run across the cornea at angles to each other

A

Stroma

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10
Q

What maintains an ordered transparency while enhancing mechanical strength of the stroma

A

Collagen fibrils within each lamella run parallel to each other and the successive lamella run across the cornea at angles to each other

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11
Q

The basement membrane of the endothelial cells

A

Descemet’s membranes

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12
Q

Single layer formed as hexagonal or honey comb structure. regulates the fluid balance of the cornea in order to maintain the stroma at about 78% hydration and thus retain transparency

A

Endothelium

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13
Q

Located between the stroma and Descemet’s membrane. It is composed of type 1 collagen bundles

A

Dua’s layer

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14
Q

What is the name for the tear film?

A

Pre corneal tear film

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15
Q

What is the most anterior refractive surface of the eye?

A

Pre corneal tear film

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16
Q

What is the pre corneal tear film made of

A

Two thin surfaces of almost equal radii

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17
Q

What is the pre corneal tear film composed of

A

Oily, aqueous and mucous layers

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18
Q

What is the optical power of the tear film?

A

48.35D

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19
Q

What is the power of the cornea and the tear film combined

A

42.36D

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20
Q

What is the tear film essential for?

A

Clear vision and reduces transparency when the tear film dries out

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21
Q

What is the stability of the tear film for

A

Optical quality of the eye

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22
Q

What is the RI of the tear film

A

1.336

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23
Q

What is the thickness of the tear film based on interferometry

A

3 microns

24
Q

What are the chief functions of the tear film lipid layer?

A
  • to provide a smooth optical surface for the cornea

- to retard water evaporation from the ocular surface

25
Q

What is tear film stability measured by?

A

Lack of stability

26
Q

What does the tear film stability refer primarily to?

A

Evaporation rate

27
Q

A stable tear film is one in which a ________

A

Minimum amount of tears evaporate

28
Q

Instability of tear film occurs due to what

A

Depletion of aqueous component of tears

29
Q

How many seconds for complete fluid movement over the surface of cornea?

A

1 second

30
Q

When does evaporation of the tear film typically occur?

A

4 seconds

31
Q

How many seconds between blinks?

A

7 seconds

32
Q

Focus camera on tear film, light reflects off fundus and illuminates tear film

A

Retroillumination

33
Q

Where is the biggest jump in refractive index as far as the tear film is concerned?

A

From air to tear film

34
Q

Why is the big jump in RI from air to tear film significant?

A

After 5 seconds or dry air… significant for optical performance

35
Q

Disorder of the tear film due to tear deficiency or excessive tear evaporation whihc causes damage to the inter palpebral ocular surface and is associated with symptoms of ocular discomfort

A

Global definition of dry eye

36
Q

How many people over the age of 50 in US have dry eye?

A

5 million

37
Q

This is a multifactorial disease Symptoms of discomfort, visual disturbance and tear film instability with potential damage to the ocular surface

A

Dry eye

38
Q

Drying of the tear film has major impact on the quality of the _______ of the eye

A

Optical system

39
Q

Subjective complaints of dry eye

A
  • dryness
  • sandy, gritty sensation
  • foreign body sensation
  • burning
  • stinging
  • excessive tearing
  • red, irritated eyes
  • blurry or fluctuating vision
  • ocular fatigue
  • light sensitivity
40
Q

What is MTF?

A

Objective unit of image quality, resolution of eye

41
Q

Lower RMS equals what?

A

Lower abberations

42
Q

How does the contact lens sit in relationship to the tear film

A

Sits in and not on the tear film

43
Q

How much thicker is the contact lens than the aqueous layer of the tear film?

A

10X

44
Q

What is the contact lens interaction with the tear film is dependent upon what?

A

Both on the lens material and on the individuals tear chemistry

45
Q

The effects of the contact lens wear on the tear film is

A
  • lens can deplete the levels of specific somponents in the tear film by soprtion (2 things get attached)
  • lens can stimulate the biochemical generation of additional components
46
Q

How far do the micovilli of the corneal epithelium stick into the precorneal tear film? What is this similar to and what is this termed?

A

1/2 micron
Green wavelength
Optically rough

47
Q

Highly diffuse reflection is caused by dysfunction of the epithelial cells

A

Stevens Johnson syndrome

48
Q

______ is important for establishing the optical integrity of the anterior corneal surface.

A

Tear film

49
Q

Tear film stability and age

A

Decreases

50
Q

Between men and women, who has a longer TBUT?

A

Men

51
Q

Between Caucasian and asians, who has a higher TBUT?

A

Caucasians

52
Q

Long time contact wearers and TBUT

A

Significantly lower

53
Q

Ocular surgery and tear film

A

Can affect it

54
Q

External environments and tear film

A
  • temperature
  • humidity
  • AC
  • air pollution
55
Q

What habits can affect tear film

A

Smoking and alcohol

56
Q

Computer use and tear film

A

Reduced blink rate and incomplete blinking pattern

Optics II block 5 (11 decks)

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