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Ocular Phys Block 9 > Phsiologic Aging Changes Of The Cornea > Flashcards

Phsiologic Aging Changes Of The Cornea Flashcards

1
Q

CCT at birth

A

Full adult thickness

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2
Q

Horistonal diamater of cornea at birth

A

10mm, 90% of the adult value

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3
Q

Axial length of cornea at birht

A

Just over 2/3 of adults

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4
Q

At birth, the cornea occupies _____ of eye surface

A

25%

15% in adults

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5
Q

Corneal aquires adult size at ____ years

A

3

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6
Q

Sclera gorws until ______ years

A

10 to 12

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7
Q

What does the sclera growing until 10 or 12 account for

A

Normal hyperopia among children.

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8
Q

When do most eyes become emmetropic

A

6 to 8 years

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9
Q

Ag related changes in the cornea and vision

A

Not detrimental to vision

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10
Q

When will vision be affected with corneal aging changes

A

If change is central cornea and affects the transparency of the tissue

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11
Q

Where do most age related corneal changes happen

A

At the periphery

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12
Q

Corneal sensitivity and aging

A

Decreases

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13
Q

Light scatter and corneal aging

A

Increases

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14
Q

Corneal curvature and aging

A

Flattening of the cornea (vertically) causing ATR astigmatism

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15
Q

Bowmans membrane and corneal aging

A

Stippling

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16
Q

Descemet’s membrane and corneal aging

A

Thickening

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17
Q

The most common aging change in the cornea

A

Corneal arcus

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18
Q

Annular yellow-white deposit located within the peripheral stroma

A

Corneal arcus

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19
Q

What is corneal arcus separated from the limbus by

A

A zone of clear cornea

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20
Q

What are the deposits in corneal arcus

A

Cholesterol or cholesterol esters

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21
Q

What does corneal arcus result from

A

Age or elevated blood cholesterol levels

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22
Q

Arcus extending over time

A

Can extend anteriorly over time to bowmans layer or into the central cornea

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23
Q

Clinical significance in those with corneal arcus

A

Non in elderly persons, but in those under age 40, hyperlipidemia should be suspected

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24
Q

What race is corneal arcus more common and pronounced

A

Blacks

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25
Q

What percent of population has corneal arcus by age 50

A

50%

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26
Q

What percent of population has corneal arcus by age 80

A

100%

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27
Q

Is corneal arcus unilateral or bilateral

A

Bilateral

28
Q

What layer of the cornea can corneal arcus effect

A

Bowmans

29
Q

What should you consider in someone with corneal arcus

A

Cardiovascular risk factors

30
Q

Corneal epithelium and aging

A

Alterations to cellular transmembrane receptors (integrins)

  • these form bridges from cell to cell and from cell to ECM
  • link cytoskeleton to ECM
  • fibronectin
  • change results in reduction in the adhesion molecules necessary for intercellular junction construction
31
Q

Los of intracellular junctions in the corneal epithelium

A

Causes a breakdown in the barrier function of hte corneal epithelium

32
Q

Decreased keratocyte density in the corneal epithelium

A

Can adversely affect wound healing and colllagen fibril degradation produces spaces that can disrupt transparency and create opacities

33
Q

Iron deposits in epithelial cell cytoplasm, mroe concentrated in basal cells, produce a horizaotnal pigmented line

A

Hudson-stahli line

34
Q

Where is a Hudson-Stahli line evident

A

At the level of the lower lid margin

35
Q

When does Hudson-Stahli line fade

A

Usually present between 50 and 70, fades after that

36
Q

What should you consider with someone who has Hudson-Stahli lines

A

Hydrochloroquine use

37
Q

Degeneration of bowmans layer

A

Lima girdle of Vogt

38
Q

Where is the limbs girls of vogt found and what color is it

A

This yellowish white opacity is located at the 3 and 9 o clock positions

39
Q

Limbal girdle of Vogt type I

A

A clear interval separating the opacity from the limbus

In type II this is not seen

40
Q

The area around the Lima girdle of Vogt

A

May include degeneration of the anterior stroma, calcium deposits, and hypertrophy of the overlying epithelium

41
Q

Changes in descemets membtane with age

A

Increases in thickness

Hassall-henle boidies increase in the periphery

42
Q

Small round peripheral endothelial indentations produced by thickening of descemets membrnae

A

Hassall-henle bodies

43
Q

Appear as corneal guttata (peripheral_

A

Hassall-Hanle bodies

44
Q

What must you rule out in Hassan-Henle bodies

A

Fuch’s

45
Q

What can Hassal-Henle bodies cause

A

Atypical arcus

46
Q

When does endothelial cell density decrease

A

With cell loss

47
Q

What is a normal endothelial cell density

A

4000 cells/mm2

48
Q

Polymegathism

A

Greater than normal variation in size of the corneal endothelial cells

49
Q

Pleomorphism

A

Increases variability in size and shape

50
Q

Pigment deposits on the posterior cornea with a vertical orientation

A

Krukenberg’s spindle

51
Q

What do you need to be careful with the a Krukenberg’s spindle

A

High IOP

52
Q

A decrease in corneal sensitivity corresponds to a loss of corneal ____with age

A

Nerves

53
Q

Changes in refractive components and in eye size must be well-balanced during childhood growth to allow for

A

Emmetropization

54
Q

When does refractive error result

A

Eye is too short or too long or if the cornea is too flat or too steep

55
Q

What is refractive error typically due to

A

Eye length

56
Q

____ may be a factor when emmetropization does not occur

A

Scleral tissue

57
Q

When does myopia usually develop

A

8-14 years

58
Q

What is myopia most often cause by

A

The lengthening of posterior eye, containing the vitreous

59
Q

Scleral connective tissue components and visual environment

A

Can change in response to changes in the visual environment

60
Q

Poor image quality on the retina and scleral tissue components

A

Poor image quality on the retina can elicit a signal to scleral tissue components to strengthen or weaken in an attempt to move the retina to the best location for a clear image

61
Q

Sunlight and myopia

A
  • altered light cycles cause eye growth and myopia in animal studies
  • a reduced risk of myopia with increased outdoor activity
  • reduction in myopia with latitudes near equator
  • either do to light intensity or greater object distances
62
Q

What does scleral remodeling cause

A

Axial lengthening that occurs in myopia; existing scleral tissue is weakened and thins. In progressive myopia, collagen is degraded, the production of newcollagen is reduced, and matric proteoglycans are lost

63
Q

Changes of the sclera during myopia development

A

Changes int he ECM but an additional piece of the puzzle may be the role played by scleral fibroblasts; if stimulated to become myofibrils. They can produce biochemical signals leading to changes in collagen production and degradation of tissue

64
Q

The progression of myopia caused by axial elongation in a highly myopic eye often causes scleral thinning, particularly at the posterior pole where the collagen fibril diamtere and the bundle size are reduced. As the sclera thins, the tissue can bulge outward causing this

A

Scleral ectasa

65
Q

Yellow sclera with age

A

Fatty deposits

66
Q

Scleral collagen and elastic fibers in aging sclera

A

Degenerate

67
Q

Fibers of the lamina cribrosa and age

A

Become stiffer and less resilient
-may make the nerve fibers passing through the openings more susceptible to injury, contributing to an increased susceptibility to glaucomatous damage.

Ocular Phys Block 9 (5 decks)

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