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Flashcards in Changes In Myopia And Aging Deck (39):
1

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

True

2

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

10mm, 90% of the adult value

3

At birth, the axial length is just over?

2/3 of adult

4

At birth, the cornea occupies ___ of the eye surface

25%

5

When does the cornea acquire adult size?

3 years

6

When does the sclera stop growing?

10-12 years

7

Do children start out hyperopic or myopic?

Hyperopic

8

When do we begin to become emmetropic?

6-8 years old

9

T/F: changes to the cornea are detrimental.

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

10

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

- 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

11

The most common aging change in the cornea

Corneal arcus

12

Describe corneal arcus

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

13

If someone has arcus under 40 what can we suspect

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

14

How does age affect the corneal epithelium?

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

15

Decreased keratocyte density can affect?

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

16

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

Hudson-Stahli line

17

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

Basal cells

18

Where is the Hudson Stahli line evident?

At the level of the lower lid margin

19

Describe limbal girdle of Vogt

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

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?

Seen: Type 1

Not seen: type 2

21

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

-degeneration of the anterior stroma
-calcium deposits
-hypertrophy of the overlying epithelium

22

What happens to the descemets membrane with age?

-increases in thickness
-Hassan-henle increase in the periphery

23

Describe Hassall-Henle bodies (descemets warts)

-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

T/F: endothelial cell density decreases with cell loss

True

25

How does aging change the corneal endothelium?

-decreases cell density

26

Greater than normal variation in size of the corneal endothelial cells

Polymegathism

27

Increased variability in size and shape

Pleomorphism

28

Pigment deposits on the posterior cornea with a vertical orientation

Krukenbergs spindle

29

T/F: Krukenbergs spindle decreases with age

False: it increases with age

30

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

True

31

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

True

32

When do people begin to develop myopia?

8-14

33

What is the most often cause of myopia?

Lengthening of the posterior pole, containing the vitreous

34

Scleral remodeling causes ____in myopia

Axial lengthening

35

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

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

36

What happens in progressive myopia?

- 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

What is scleral ectasia?

Scleral tissue bulging due to scleral thinning

38

How does age affect the sclera?

- 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

How would the change in lamina cribrosa pores affect us?

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