NMH14: missing stuff Flashcards
What is in the limbus
(corneal stem cells)
Where is the lacrimal gland located
In orbit, latero-superior to the globe, produces watery tears
Why is pressure not releaved from puncta during sneezing
Valve in canaliculi (prevents retrograde reflux of fluid from the sac into the canaliculi)
Compare water content of sclera and cornea
sclera- high cornea- low
Why is cornea refractive
Convex curvature Higher refractive index than air
Other function of cornea other than refraction
Physical Barrier Infection Barrier
5 layers of cornea
1 – Epithelium 2 – Bowman’s Membrane 3 – Stroma – regularity contributes towards transparency 4- Descements membrane 5. Endothelium (Epstein Bar Sung Down Eltham-acronym to remember.
What contributes to corneal transparency
Regularity of stroma And the lack of water because endothelial cells pump it out
What is and is not present in stroma
is- corneal nerve endings providing sensation and nutrients for healthy tissue Is not- blood vessels
What does endothelium of the cornea do
pumps fluid out of corneal and prevents corneal oedema, 1 layer
Why, with age, can you get corneal oedema and cloudiness
Endothelial layer pumps water from the more superifical stromal layer Only 1 layer of endothelial cell, and they have no regeneration power Endothelial cell density decreases with age Endothelial cell dysfunction may result in corneal oedema and corneal cloudiness
What happens if you hydrate hte cornea
It goes opaque
What nourishes the outer and inner part of the retina
Outer part: choroid Inner part: central radial artery
What is responsible for refractory power of the eye
2/3- cornea 1/3 lens
What is cataracts
Lens loose transparency with age
