Changes in Myopia and Aging Flashcards Preview

Ocular Physiology > Changes in Myopia and Aging > Flashcards

Flashcards in Changes in Myopia and Aging Deck (19):
1

At birth, the cornea's diameter is....

10mm
90% of adult

2

Cornea grows to adult size at age....

3

3

Sclera grows to adult size at age....

10 - 12

4

Eyes should be emmetropic by age....

6 - 8
due to cornea and scleral growth

5

Aging Changes of Cornea

decrease in sensitivity
increase light scatter
flattens - against the rule
stippling of Bowman's membrane
thickening of Descemet's membrane

6

Corneal Arcus

bilateral ring of cholesterol and cholesterol esters in peripheral stroma; extends into Bowmans
if under age 40- hyperlipidemia

7

Integrins

form bridges from cell to cell or cell to extracellular matrix
aging causes reduction of adhesion molecules needed for intercellular junctions

8

Loss of Intracellular Junctions

breakdown of barrier function of corneal epithelium

9

Hudson-Stahli Line

iron deposits in epithelial cell cytoplasm
evident at lower lid margin
age 50-70
increased by hydroxychloroquine

10

Limbal Girdle of Vogt

degeneration of Bowman's layer
yellow-white opacity at 3 and 9 positions

11

Changes in Descemet's Membrane with Age

increases with thickness
Hassall- Henle bodies increase in periphery

12

Hassall- Henle Bodies

asymptomatic; small round peripheral indentations
from thickening of Descemet's
appear as corneal guttata
can cause atypical arcus

13

Aging Changes to Corneal Endothelium

Decrease in cell density
more variation in size and shape

14

Krukenberg's Spindle

pigment deposits on the posterior cornea with vertical orientation

15

Why does corneal sensitivity decrease with age?

loss of corneal nerves

16

Emmetropization

generally due to eye length
scleral tissue may be factor when this does not occur

17

Scleral Remodeling

causes axial lengthening resulting in myopia
sclera weakens and thins

18

Scleral Ectasia

sclera thins and appears blue
tissue bulges out

19

Changes of Sclera with Age

fatty deposits make sclera yellow
collagen and elastic fibers degenerate- thinning
lamina cribrosa fibers become stiffer and less resilient