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Ocular Phys > Changes In Myopia And Aging > Flashcards

Changes In Myopia And Aging Flashcards

1
Q

T/F: at birth the cornea has full adult thickness

A

True

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2
Q

At birth, what is the horizontal diameter of the cornea?

A

10mm, 90% of the adult value

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3
Q

At birth, the axial length is just over?

A

2/3 of adult

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4
Q

At birth, the cornea occupies ___ of the eye surface

A

25%

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5
Q

When does the cornea acquire adult size?

A

3 years

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6
Q

When does the sclera stop growing?

A

10-12 years

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7
Q

Do children start out hyperopic or myopic?

A

Hyperopic

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8
Q

When do we begin to become emmetropic?

A

6-8 years old

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9
Q

T/F: changes to the cornea are detrimental.

A

False. It isnt detrimental unless there is changes to the central cornea or the transparency

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10
Q

What are the 5 changes of the cornea due to aging?

A
  • decrease in corneal sensitivity
  • increase in light scatter
  • flattening of the cornea (especially vertically)
  • –against the rule
  • stippling of bowmans membrane
  • thickening of descemets membrane
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11
Q

The most common aging change in the cornea

A

Corneal arcus

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12
Q

Describe corneal arcus

A

Yellow-white deposit located in the peripheral stroma

  • the deposits are cholesterol and cholesterol esters
  • Ring separated from the limbus by a zone of clear cornea

Asymptomatic
Bilateral
Involves Bowmans layer

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

Normal in people 60-80 years old

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13
Q

If someone has arcus under 40 what can we suspect

A

That they have high cholesterol, so we need them to get that checked

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14
Q

How does age affect the corneal epithelium?

A

Alternations to the cellular transmembrane receptors (integrins) can occur
- this causes a reduction in the adhesion molecules necessary for intercellular junction construction

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15
Q

Decreased keratocyte density can affect?

A
  • wound healing

- collagen fibril degradation produces spaces that can disrupt transparency and create opacities

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16
Q

Iron deposits in the epithelial cell cytoplasm that produces a horizontal pigmented line

A

Hudson-Stahli line

17
Q

Where is the iron deposits (Hudson stahli) more concentrated?

A

Basal cells

18
Q

Where is the Hudson Stahli line evident?

A

At the level of the lower lid margin

19
Q

Describe limbal girdle of Vogt

A

Degeneration of bowmans layer

Yellowish opacity located at the 3 and 9 o’clock positions

A clear interval separating the opacity from the limbus may be seen

20
Q

What type of limbal girdle of Vogt will you see a clear interval separating the opacity from the limbus?

What type will not be seen?

A

Seen: Type 1

Not seen: type 2

21
Q

What other factors may you be able to see with limbal girdle of Vogt?

A
  • degeneration of the anterior stroma
  • calcium deposits
  • hypertrophy of the overlying epithelium
22
Q

What happens to the descemets membrane with age?

A
  • increases in thickness

- Hassan-henle increase in the periphery

23
Q

Describe Hassall-Henle bodies (descemets warts)

A
  • asymptomatic
  • Small round peripheral endothelial indentations
  • Produced by thickening of Descemet’s membrane
  • Appear as corneal guttata (peripheral)
  • Peripheral Edema
  • May cause atypical arcus
24
Q

T/F: endothelial cell density decreases with cell loss

A

True

25
Q

How does aging change the corneal endothelium?

A

-decreases cell density

26
Q

Greater than normal variation in size of the corneal endothelial cells

A

Polymegathism

27
Q

Increased variability in size and shape

A

Pleomorphism

28
Q

Pigment deposits on the posterior cornea with a vertical orientation

A

Krukenbergs spindle

29
Q

T/F: Krukenbergs spindle decreases with age

A

False: it increases with age

30
Q

T/F: A decrease in corneal sensitivity corresponds to a loss of corneal nerves with age.

A

True

31
Q

T/F: myopic eyes are longer than emmetropic or hyperopic eyes

A

True

32
Q

When do people begin to develop myopia?

A

8-14

33
Q

What is the most often cause of myopia?

A

Lengthening of the posterior pole, containing the vitreous

34
Q

Scleral remodeling causes ____in myopia

A

Axial lengthening

35
Q

When the axial length of the eye increases, how does the affect the sclera?

A

It causes it to stretch the scleral tissue. This weakens and thins the tissue

36
Q

What happens in progressive myopia?

A
  • existing collagen is degraded
  • production of new collagen is decreased
  • matrix proteoglycans are lost
  • scleral thinning in the posterior pole
  • collagen fibril diameter and bundle size are reduced
37
Q

What is scleral ectasia?

A

Scleral tissue bulging due to scleral thinning

38
Q

How does age affect the sclera?

A
  • build up of fatty deposits can cause it be appear yellow
  • scleral collagen and elastic fibers degenerate
  • concentration of some proteoglycans decrease
  • fibers of the lamina cribrosa become stiffer and less resilient
39
Q

How would the change in lamina cribrosa pores affect us?

A

It may make nerve fibers passing through the openings more susceptible to injury, contributing to an increased susceptibility to glaucomatous damage

Ocular Phys (6 decks)

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