Crystalline Lens Flashcards
(16 cards)
Which pole is steeper?
Posterior pole
Adult crystalline lens diameter blanks but thickness blanks
Doesn’t change, increases 0.02 mm per year.
Why does the lens have non uniform refractive index?
Non uniform distribution of crystalline proteins in the lens fibers
What part of lens doesn’t have epithelium?
Posterior capsule
Lens capsule is thickest blank and thinnest blank
Anteriorly (20 microns), posteriorly (3 microns)
What type of collagen fibers make the lens capsule?
Type IV
What are the 2 main functions of the lens capsule?
Diffusion barrier freely permeable for low weight molecules.
Makes lens pliable to be pulled on during accommodation.
Zonular lamella
Outer most layer of capsule to which zonules will attach
Function of lens epithelium
Proliferates a germanative zone at equator to form lens fibers.
Secretes lens capsule.
Central anterior lens epithelium involved in transport of substances from aqueous humor to inner lens.
What type suture is on a posterior surface cataract?
Inverted y suture
What type of suture is on an anterior surface cataract?
Upright y suture
Nutrient and ion exchange occurs through many what?
Gap junctions
Divisions of lens inner to outer
Embryonal nucleus, fetal nucleus, adult nucleus, lens cortex
Which layer of the lens contains the y sutures?
Fetal nucleus
Cortical cataract, outer portion of lens is affected
Only have trouble seeing when eye is dilated
Posterior subcapsular cataract, inner portion affected
No trouble when eyes are dilated
