histology of the eye Flashcards
corneal layers
outer epithelium bowman's membrane substantia propria descemet's membrane corneal endothelium
outer epi
nonkeratinized squamous
bowman’s membrane
thin BM
substantia propria
dense collagenous tissue w/spare kartinocytes
descemet’s membrane
thick BM
corneal endothelium
responsible for active transport of fluid out of SP and allowing diffusion of metabolites from aqueous humor
myopia
nearsightedness
light focused ant to retina
cornea is too curved or lens too powerful for length of globe
hyperopia
farsightedness
light focuses post to retina
lens and cornea too weak
LASKIK
corneal epi cells are replaced by mitotic cells found in periphery which migrate into wound
chorioid
posterior pigmented portion of vascular layer
loose CT, fibroblasts, and melanocytes
Bruch’s Membrane (separates it from retina)
choriocapillaris- area next to retina rich in capillaries
drusen
accumulation of amyloid btwn bruch’s membrane and pigmented epithelium
due to normal aging
first sign of macula degeneration
ciliary body
forward continuation of Uveal (vascular) layer
wedge shaped btwn iris and vitreous body
ciliary body contains
loose CT pigmented epi nonpigmented epi (filtrate plasma creates aqueous humor) smooth m zonule fibers
zonule fibers
radiate from ciliary processes to lens
form suspensory ligaments of lens
ciliary m bundles
3:
1 opens canal of schlemm
2 stretch ciliary body
near by accommodation
ciliary m contracts
tension on suspensory ligs releases
lens gets thicker and more convex
distant accommodation
ciliary m relaxed
tension on suspensory ligs increases
lens gets thinner and less convex
flow of humor
ciliary processes has epithelial folds w/core rich in fenestrated capillaries which continuously produce aqueous humor
passes thru papillary aperture btwn iris and lens into ant chamber
drains thru trabecular meshwork into canal of schlemm and into venous circulation
corneal-irideal angle
area btwn endothelial cells fo cornea and ant surface of iris
canal of schlemm forms complete circle here
open-angle glaucoma
most common form
corneal irideal angle open
increased IOP
slow neurodegenerative process w/characteristic optic nerve cupping
treatment of open angle glaucoma
prostaglandins
beta-blockers
alpha adrenergic agonists
trabeculectomy or trabeculoplasty
angle-closure glaucoma
corneal-irideal angle obstructed aqueous outflow impeded primary- unknown or congenital cause seconday- inflammation, hemmorage, neovasulization, or tumor conjunctival redness common
iris
colored, ant extension of ciliary body
controls pupillary aperture
separates ant and post chambers
2 concentric rings (pupillary and ciliary zone)
pupillary zone
nearest the pupil and thickest area
ciliary zone
nearest the ciliary body and widest area
ant surface of iris
fibroblasts and pigmented melanocytes embedded in extraoccular matrix
eye pigmentation is determined by number of melanocytes here
stoma of iris
well vascularized loose CT w/vessels arranges radially
contractile elements of iris
myoepthelial cells make up dilator pupillae m
smooth m makes up sphincter pupillae m
post surface iris
pigmented epi, continuous w/ciliary body
lens
transparent, biconvex, avascular supported by zonule fibers making up suspensory ligs 3 components: lens capsule lens epi lens fibers
lens capsule
thick transparent basal lamina
lens epithelium
single layer of cuboidal cells
only present on ant and lateral surface
lens fibers
around 2000 hexagonal and elongated terminally differentiated cells
loose nuclei and organelles during maturation
filled w/crystallins (proteins that increase refractory index of lens)
cataract
leading cause of blindness in the world
lens does not shed nonviable cells
lens fibers do not have intracellular mechanism to deal w/accumulation of substance
photo/oxidative damage
risk factors for cataract
advanced aging smoking sun exposure alcohol consumption metabolic syndrome diabetes mellitus malnutrition inactivity
