9 Aging And The Cornea Flashcards
T/F at birth the cornea has the full adult thickness
True
In newborns the axial length of the eye is ____ of an adults
2/3
When does the cornea reach adult size
Age 3
The sclera grows to what age
10-12
When do most eyes become emmetropic
6-8
Aging changes to the cornea impede vision
No, only if the central cornea is affected or the transparency is affected
As we age what happens to corneal sensitivity
It decreases
As we age what happens to light scatter
It increases
Does teh cornea get flatter or steeper as we age
Flatter
What happens to Bowmans membrane
It stipples
What happens to descemets membrane
Thickens
What is the most common aging change in the cornea
Arcus
What is arcus
An annular yellow-white deposit in the peripheral stroma
What makes the deposits in arcus
Cholesterol and cholesterol esters
What can cause arcus
Age or elevated blood cholesterol levels
Should we be concerned when we see arcus
NO, not unless it is in a person less than 40 y.o.
by age 50 what percent of the population has arcus
50%
By age 80 what percent of the population has arcus
100%
Is arcus unilateral or bilateral?
Bilateral
What changes happen in the corneal epithelium
Alterations in the transmembrane receptors resulting in a reduction in the adhesion molecules
What does loss of intracellular junctions in the corneal epithelium cause
Breakdown of the epithelium function
Decreased keratocyteis in the epithelium affects what
Wound healing
Collagen fibril degradation in the epithelium has what affect on the cornea
Opacities
What is the Hudson-Stahli line?
Iron deposits in the epithelium, created a horizontal pigmented line. Evident at the lower lid margin
What is the Kimble girdle of Vogt
Degeneration of Bowmans layer. Located at 3 and 9 o clock. Evident as a yellowish opacity
What are Hassall-Henle bodies?
Small round endothelial indentations caused by thickening of descemets membrane. Appear as corneal guttata
What happens to endothelial cell density
Decreases with cell loss
What changes occur in endothelium
Decrease in cell density
Polymegalism (large cells)
Pleomorphism (increased variable size and shape)
What are Krukenbergs spindle
Pigment deposits in posterior cornea with vertical orientation
What happens to corenal sensitivity with age?
Decreases due to loss of corenal nerves
What must occur for emmetropizaton happen
Changes in refractive components and the eye size must be well balanced during growth to allow emmetropization
What is the usual cause of refractive error
Eye length
When does myopia occur
8-14 years
What is the main cause of myopia
Lengthening of posterior eye
There is a reduced risk of myopia with (increased/decreased) outdoor activity?
Increased
What does scleral remodeling cause
Axial lengthening that occurs in myopia, the scleral tissue is weakened and thins
What is scleral ectasia
Tissue bulge on the sclera caused by thinning
What refractive error has a higher risk of ectasia?
Myopia
As fatty deposits accumulate what happens to the sclera
Yellows
What happens to proteoglycans in the sclera
Decrease
What happens to the lamina cribrosa
Becomes stiffer and less resilient making eye more susceptible to glaucomatous damage
