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Ocular Bio Test 1
Overview of Visual System,Cornea/Sclera, Uvea, Retina, Lens
151
Anatomy
Graduate
10/03/2010

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Cards

Term

Outer Tunic of eye

Fibrous

Definition
Cornea and Sclera
Term

Inner Tunic of Eye

 Neural

Definition
the retina
Term

Middle Tunic of Eye

Vascular AKA Uvea

 

Definition
Iris, Ciliary Body, Choroid
Term
Limbus
Definition
Transitional region between the cornea/sclera
Term
Cornea
Definition
transparent and allows light to enter the globe
Term
Conjunctiva
Definition
covering of sclera
Term
Sclera
Definition
opaque white of the eye
Term
Iris
Definition
Structure that regulates the amt of light entering the pupil
Term

Ciliary Body

Definition

Structure that produces aqueous humor and contains the muscle that controls the lens

Term
Choroid
Definition
Contains network of blood vessels that supplies the outer retinal layers
Term
Retina
Definition
This processes light and transmits visual info the the rest of the brain through the optic nerve
Term
Anterior Chamber
Definition
Bounded by the cornea anteriorly and the iris/front of lens posteriorly. Contains aqueous humer
Term
Posterior Chamber
Definition
Lies behind the iris and surrounds the equator of the lens--the   Contains aqueous humor
Term
Aqueous Humor
Definition
provides nourishment to the lens/cornea and surrounding structures (where there is no blood supply)
Term
Crystalline Lens
Definition
structure located in posterior chamber and provides refractive power--(and adjustable ref. power)
Term
limbus
Definition
region that represents a change in pattern and characteristics of the collagen and cells that make up the outer fibrous layer
Term
Schlemm's Canal
Definition
Main channel that collects the aqueous humor--located at the limbus
Term
extraocular muscles
Definition
muscles that insert into the scleral covering of eye
Term
lamina cribosa
Definition
portion of sclera that continues across optic nerve and forms perforated layer through which the optic nerve fibers pass on the way to the brain
Term
Vitreous humor
Definition
gel like substance in vitreous body--there for life(not replaced)
Term
pupil
Definition
structure that is reflexively enlarged or reduced by the iris dilator and sphincter muscles
Term

Zonular Fibers

aka ciliary fibers

Definition
what runs between the equator of the lens and the inner surface of the ciliary body
Term
choroid
Definition

This begins at the optic nerve posteriorly and extends to the ora serrata anteriorly. 

 

Also provides nutrition to the photoreceptor layer of the retina.

Term
retina
Definition
this externds anteriorly from the the optic nerve and ends at the ora serrata
Term
Ora serrata
Definition

junction between ciliary body and the retina

Nerve cells of the retina stop here

Term
Macula
Definition
region of the retina that contains the fovea and foveola
Term
Foveola
Definition
Part of fovea that contains highest density of cones
Term
Vitreous body
Definition
this bounds the posterior of the posterior chamber.  Also forms a depression which confrims to the posterior surface of the lens
Term
[image]
Definition
Know the Flow of Aqueous Humor
Term
Anterior/Ventral
Definition
toward the front
Term
Posterior/Dorsal
Definition
toward the back
Term
Superior/cranial
Definition
toward the head
Term
Inferior
Definition
away from the head
Term
Rostral
Definition
toward the nose
Term
medial
Definition
toward the midline
Term
lateral
Definition
away from the midline
Term
proximal
Definition
near the point of origin
Term
distal
Definition
away from the point of origin
Term
sagittal
Definition
vertical plane--divides left and right
Term
coronal
Definition
vertical plane--divides front and back
Term
tranverse
Definition
horizontal plane--divides into superior and inferior (top/bottom)
Term
caudal
Definition
towards the tail
Term
emmetropia
Definition
light correctly focused on the retina
Term
hyperopia
Definition

distance from cornea to retina is too short

focal point behind retina

Term
myopia
Definition

distance from cornea to retina is too far

focal pt is in front of retina

Term
keratometer
Definition
instrument that measures the curvature of the central cornea
Term
retinoscope
Definition
instrument that measures accomodative function and optical power of the eye with a set of lenses
Term

slit-lamp

aka biomicroscope

Definition
used to image the eyelids and outside of globe. Good to view transparent structures (cornea/lens)
Term
perimeter
Definition
instrument used to test the extent, sensitivity, and completeness of one's visual field
Term
Basement Membrane
Definition
formed by epithelial cells--attaches epi cells to connective tissue
Term
basal lamina
Definition
part of basement membrane secreted by epi cells
Term
reticular lamina
Definition
part of basement membrane that is a product of connective tissue layer
Term
stratified
Definition
several layers of epi cells
Term
simple
Definition
1 layer of epi cells
Term
Keratinized Epi
Definition
tougher than regular epi. Protects against dehydration, bacteria, and injury
Term
stratified squamous epi
Definition
epithelium with apical squamous cells, basal cuboidal or columnar--function:Protection
Term
stratified cuboidal epi
Definition
more than1 layer of cuboidal cells Function:secretion/absorption
Term
Stratified Columnar Epi
Definition

Single layer columnar then several cuboidal layers

Function:protection/secretion

Term
transitional epi
Definition

cell types vary and are often multi-nucleated--

Function: distention (Bladder, ureter, etc)

Term
exocrine glands
Definition
secrete into a duct
Term
endocrine glands
Definition
secrete directly into the blood
Term
apocrine glands
Definition
secrete part of the cell cytoplasm
Term
merocrine glands
Definition
secrete product that has no part of cell
Term
Zonula Occludens
Definition
junctions that are tight--nearly impermeable to fluids
Term
Zonula Adherens
Definition
junctions that are intermediate
Term
Macula Adherens
Definition
Strong spot like attachements between cells
Term
Gap Junctions
Definition
communicating junctions that allow cytoplasm to pass between cells.  (direct communication between cells)
Term
Smoothe Muscle tissue
Definition
tissue in which fibers are elongated, cells are slender,have 1 central nucleus
Term
striated muscle
Definition
tissue that has regular pattern of light and dark bands
Term
neurons
Definition
specialized cells that react to stimulus and conduct nerve impulses
Term
neuroglia
Definition
cells that provide structural and metabolic support in nerve tissue
Term
dendrites
Definition
receives the message in neuronal communication
Term
axons
Definition
transmits the message in neuronal communication
Term
myelin
Definition
insulation that improves conduction speed of neurons
Term
Schwann cells
Definition
cells that produce myelin the the PNS
Term
synapse
Definition
Specialized junction where impulses are transmitted from 1 neuron to the next
Term
10-50 to 1
Definition
ratio of neuroglial cells to neurons
Term
astrocytes
Definition
neuroglial cells that provide structure and nutrition
Term
Oligodendrocytes
Definition
Neuroglial cells that produce myelin in the CNS
Term
Microglia
Definition
Neuroglial cells that possess phagocytic properties.  Increase in areas of damage or disease
Term
astigmatism
Definition
this condition results from unequal refraction of light by different meridians of the refracting elements
Term
Reg. Astig.
Definition
Astig. where longest and shortest radius of curvature are 90 degrees apart
Term
Irregular Astig.
Definition
Astig. where meridians corresponding to the greatest difference are not 90 degrees apart
Term
With the rule Astig
Definition
Astigmatism where the vertical medirian has the steepest/shortest radius of curvature.  Football on its side
Term
Against the rule Astig
Definition
Astigmatism where the horizontal meridian is steepest.  football standing up on tip
Term
Oblique Astig
Definition
Astigmatism where greatest differences are not at 90 & 180(+ - 30), but at 45&135 degrees(+-15)
Term
5-7 layers of cells (50microns)
Definition
thickness of Corneal Epithelium
Term
8-15 microns
Definition
Thickness of Bowmans layer of Cornea
Term
Lamellae
Definition
Flat bundles of collagen fibrils in stroma that run parallel to one another across whole cornea from limbus to limbus. (they do have a random pattern see slide 12 of cornea lecture)
Term
500 microns--  90% of total thickness
Definition
thickness of corneal stroma
Term
Keratoconus
Definition

corneal dystrophy--starts with focal disruptions of basement membrane and bowman's layer.

Stroma thins, and unaffected area projects outward in a cone shape b/c of IOP.

Term
5 microns thick
Definition
thickness of corneal endothelium
Term
Corneal Endothelium
Definition

This layer of the cornea governs fluid and solute transport across posterior of cornea from the aq. humor.  (Maintains slight dehydrated state of cornea)

Cells here are also 6,7 sided

Term
Corneal Endothelium cells
Definition
Cells that have the 2nd highest metabolic rate behind the photoreceptors (have lots of Mitochondria)
Term
Endothelial Mosaic
Definition
the regular arrangement of corneal endothelial cells
Term
Pleomorphism
Definition
Increase or loss in variability of corneal endothelium cell shape
Term
polymegathism
Definition
Increase or decrease in cell size of corneal epithelium cells
Term

Hassall Henle (in periphery of cornea)

or

Guttata (in center of cornea)

Definition

Deposits/mounds of basement membrane material created by the corneal endothelium.  The mounds have thinned endothelium so barrier is compromised.  Shows up as periodic thickenings in Descemet's membrane. 

 

Term
Contact Lens Wear
Definition
epithelial thinning, stromal thinning, decrease in keratocytes, pleomorphism and polymegathism--all of these can be a result of :
Term
Microvilli
Definition
finger-like projections on the corneal epithelium increase surface area(enhance tear film stability)
Term
Microplicae
Definition
ridge-like projections on the corneal epithelium increase surface area(enhance tear film stability)
Term
zonula occludens (tight junctions)
Definition
Type of junctions on the apical surface of the cornea.
Term

surface cells:2 nonkeritinzed squamous cells

wing cells: middle layer (2-3) cells

basal cell: 1 layer pf columnar cells--(mitosis occurs here)

 

(WHOLE EPITHELIUM REPLACED ~weekly) 

 

Definition
cell make up of corneal epithelium
Term
RCE Recurrent Corneal Erosions
Definition

This occurs as a result of damage to basal cell layer of corneal epithelium and can take months to heal (whereas damage to surface heals in hours). 

 

Also classifed by failure of basal cells to attach to bowman's layer and exposed corneal nerves so painful condition.

Term
Bowman's Layer
Definition
layer of the cornea that is a dense, fibrous sheet of interwoven collagen fibrils randomly arranged and is transitional to the stroma.  It's only function: to resist damage. 
Term
Keratocytes
Definition
Cells that maintain corneal stroma by synthesizing collagen and extracellular matrix components. They are arranged in a corkscrew pattern and are flattened cells that lie between lamellae
Term
white blood cells, lymphocytes, leukocytes, and white blood cells--these increase in pathologic conditions and affect transparency.
Definition
Cells that are inbetween lamellae other than Keratocytes
Term
the scatter is minimal and separated by small distances (less than 1% scattered)
Definition
Why is scattering in the cornea minimal if the epithelium, bowman's and descemets layers are irregularly arranged?
Term
Descemets layer
Definition
This is considered the basement membrane of the corneal endothelium. It also is constantly growing through life--doubles in size by age 40
Term
Scwalbe's Line or Ring
Definition
thickened area of collagenous connective tissue at the descemets termination in the limbus
Term
Endothelium
Definition
innermost layer of the cornea that is adjacent to the anterior chamber
Term

Cornea 43-48D

Lens 15-18 D

Definition
The cornea and lens each account for how many diopters of the eye's total refractive power?
Term
Pterygium
Definition
benign growth on cornea due to UV exposure
Term

Photokeratitis

aka arc eye (welding) pr snowblindness(snow, sand, water)

Definition
painful condition as a result of acute UV exposure
Term
Corneal Edema
Definition
damage to cornea epi or endo can result in this.  An increase in fluid retention occurs and the posterior stroma and descemet's buckle forming vertical lines called striae
Term
REVIEW SLIDE 23 in Cornea lecture--know if/how each layer of cornea is replaced after injury
Definition
Term
Corneal Neovascularization
Definition
this is the excessive growth of blood vessels from the limbal vascular plexus into the cornea--due to low oxygen reception. Can be stopped, but empty vessels remain as ghost vessels.
Term
Descemets and Endothelium
Definition
Which layers of the cornea have no nerve endings?
Term

Long and short ciliary nerves go into the stroma, and then branch into mid-stroma, subepithlium and epithelium.

Also has sympathetic nerve fibers for metabolism, prolieferation and wound healing. 

Definition
Innervation of the cornea
Term
Naked Nerve endings
Definition
These are the termination of nerve endings in corneal epithelium--make corneal abrasions painful
Term
sclera
Definition
this maintains the shape of the globe, offers resistance to internal and external forces, and is where the extraocular muscles attach
Term
.33mm at the posterior and about 1 mm by the time it gets to the anterior
Definition
Sclera thickness distribution
Term
Myopic eye generally larger the emmetropic eye--thinning of sclera may be a factor when emmetopia doesn't occur
Definition
Sclera and Myopic development
Term
scleral spur
Definition
this is the origin of longitudinal ciliary muscle fibers posteriorly.  Anteriorly it is continuous with the trabecular meshwork. It's a region of circularly oriented collagen bundles that extends from the inner aspect of the sclera 
Term
Iridodialysis
Definition

this is when the thin root of of iris tears away from the ciliary body as a result of blunt trauma--can result in damaged blood vessels and nerves.

 

Blood can also leak into either ant. or post. chambers and cause nerve damage that may paralize iris muscles

Term

blue:in newborns or peoole with connective tissue disease.

Yellow: b/c of fatty deposits.  Can happen with age and liver disease.

White:  healthy sclera

Definition
Scleral colors-blue vs white vs yellow
Term
the cornea
Definition
where is the anterior scleral foramen?
Term
where the optic nerve passes through.
Definition
where is the posterior scleral foramen?
Term
the optic nerve--so can foreshadow for disease processes
Definition
where is the weakest area in the outer tunic?
Term
Optic Nerve Cupping
Definition
ectasia or cupping out of the center area of the surface of the optic nerve.  May be evident in pts with increased IOPs
Term
scleral canals
Definition
these pass through the sclera and carry nerves and vessels.  They're also possible routes for disease to exit or enter the eye
Term
middle apertures
Definition
the canals of the sclera that lie 4mm posterior to the equator and carry the vortex veins
Term
posterior apertures
Definition
these canals are located around posterior scleral foramen(where optic nerve is)--passages for posterior ciliary arteries and nerves
Term
anterior apertures
Definition
these canals are near the limbus at the muscle insertions.  They're passages for anterior ciliary vessels which are branches from the muscular arteries
Term
the sclera is avascular, gets nourishment from episcleral and choroidal vessels, along with long posterior ciliary arteries.
Definition
scleral blood supply
Term

posterior--innervated by short ciliary nerves

rest of sclera--by long ciliary nerve branches

Definition
scleral innervation
Term
external scleral sulcus
Definition
the radius of curvature changes at this part of the corneoscleral junction, creating a shallow, narrow furrow.
Term
the palisades of vogt
Definition
these are radial projections of the limbal epithelium and stroma and extend into the cornea in spike like fashion.
Term
orthokeratology
Definition
method of contact lens fitting to change the shape of the cornea to correct refractive error
Term
Hudson-Stahli Line
Definition
iron deposits in corneal epithelial cell cytoplasm, more concentrated in the basal cells.  Can ususally see this at the lower lid margin. Normal w/age
Term
Corneal Arcus
Definition
most common corneal aging change-circular yellow-white deposit in the peripheral stroma
Term
limbal girdle of vogt
Definition
yellowish white opacity caused by of the bowmans layer of the cornea at 3 and 9 o'clock--normal w/age
Term
krukenber's spindle
Definition
pigment deposits on the posterior cornea that have vertical orientation
Term
posterior synechia
Definition

the posterior iris surface is adherent to the anterior lens surface

 

If involves a large part of the iris aq. humor will build up in post. chamber. This causes the iris to bow forward into an Iris Bombe

Term
Iridectomy
Definition
surgically removing a wedge of the iris so that aqueous humor can flow between the ant and post chambers
Term
Iridotomy
Definition
Poking a hole in the iris(usually with a laser) to allow aqueous humor to flow between ant. and post. chambers
Term
Anterior Chamber Angle
Definition
this is located at the limbus and is contains trab. meshwork and schlemm's canal where aq.humor drains
Term

anterior synechia

aka PAS peripheral anterior synechia

Definition

the anterior iris surface is adherent to the trabecular meshwork.

 

 

Term
dispersion syndrome
Definition
pieces of iris pigment break off posterior iris and may compromise aq. humor flow.
Term
heterochromia
Definition
a person's irises are differnet color, or a portion of the iris is different from the rest.
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