Crystalline Lens B7 Flashcards
Is there blood supply in the lens?
No blood supply
The lens is a ____________ structure that is located posterior to the iris and pupil and anterior to the vitreous body
Biconvex
Which curvature is steeper, anterior or posterior curvature?
Posterior curvature is far steeper (5-8 mm ROC) Anterior curvature (8-14 mm ROC)
Where are the poles?
at the center of the anterior and posterior curvature. Anterior and posterior poles
At birth the lens diameter is _____.
As an adult the lens diameter is ____.
6.5 mm
10 mm
Lens diameter doesn’t increase significantly with age, but lens thickness increases 0.02 mm per year
How much power does the lens have?
15-20 D of total 60 D
Power is reduced to +8 by age 40 (presbyopia)
reduced even further to +1 or +2 by 60
The lens equator is only ____ away from the ciliary processes of the pars plicata
0.5mm
What is the indent where the lens sits posteriorly?
Patellar fossa
What is the ligament at the back of the lens connecting to the vitreous or posterior zonules?
Wieger’s ligament
What is the space in the posterior part of the lens that is between the patellar fossa and the lens.
Berger’s space
What are the 3 parts of the crystalline lens?
Elastic capsule
-thickest in the body (20 microns)
-in direct contact with anterior lens epithelium
Lens Epithelium
-anteriorly the capsule is secreted by anterior lens epithelium
-posteriorly there is no epithelium (3 microns thick)
Lens fibers
-secrete the posterior lens capsule
How thick is the anterior lens capsule?
How bout the posterior lens capsule?
20 microns
3 microns
Are there elastic fibers in the capsule?
NOOOOOO
Anterior capsule _________ with age.
increases
1/3 larger by age 65
What are the lens capsule functions?
Diffusion barrier
Makes lens Pliable for accommodation
What layer of the lens do the zonules attach?
Zonular Lamella (outer most layer of lens)
What kind of cells does the lens epithelium have?
MONOLAYER of CUBOIDAL cells
NO POSTERIOR EPITHELIUM
(epithelial cells proliferate through life, and stretch and become columnar in shape)
The lens epithelium proliferates at _________________, at equator to form lens fibers. And secretes the lens ______.
Germanative zone
capsule
_________________ is involved in the transport of substances from aqueous humor to lens interior.
Central anterior epithelium
Is there epithelium on posterior side of lens?
NO!
