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C/S Limbus & IOP

Corneal-scleara limbus and intraocular pressure, Glaucoma, and Choroid

QuestionAnswer
Because the cornea doesn't contain blood vessels the capillaries of the conjuctiva and the the episclera....? end in loops near the limbus
The trabecular meshwork can be described as...? spongy
The trabecular meshwork is lined by...? trabeculocytes
What allows aqueous to drain into Schlemm's canal? The trabecular meshwork
Intraoccular pressure remains normal when...? some of the aqueous produced by the cilliary body flows out freely
What is a common site in the eye for surgical incisions? The corneal-sclera limbus
The limbus is _____ mm wide. 1-2
How thick is the limbus from anterior to posterior? 1 mm
Where is the proximal margin? At the termination of the clear cornea
What is the distal margin? A line runs through the scleral spur and is a point of reference during ocular surgeries.
What is a scleral spur? A ridge that runs through the cilliary body and sclera.
What are the two parts of the corneal-sclera limbus? Epithelium and stroma
How many cell layers are in the corneal-sclera limbus epithelium? 10
Which is thicker the corneal epithelium or the corneal-sclera limbus epithelium? The corneal-sclera limbus epithelium
What happens in the corneal-sclera limbus stroma? The lamellae lose their regular arrangement and lose transparency.
What contains the drainage system for aqueous humor? Corneal-scleara limbus
What is the angle structure? Where an angle is formed between the cornea and the iris.
What is contained in the angle structure? Trabecular meshwork and Schlemm's canal.
What is the trabecular meshwork made up of? Many layers of perforated tissue
What is the function of the trabecular meshwork? It is where the aqueous humor perculates and drains into Schlemm's canal
What is Schlemm's canal? A tube that goes around the limubs and collects aqueous humor.
What are the collecting tubes? Deliver aqueous from the Sclemm's canal into the cilliary veins where it is carried off like other waste by the cardio-vascular system
What percentage of the aqueous that goes into the anterior chamber is absorbed and reused? 20%
What nourishes the corneal periphery? Capillaries in the limbus
What is normal intraocular pressure? 10 - 20 mm Hg
What is the average intraocular pressure? 15.5 mm Hg
What is used to measure intraocular pressure? Tenometer
The trabecular meshwork must have less than __ mm Hg? 10
What are the reasons for raised intraocular pressure? Time of day; excessive aqueous production; inadequate aqueous drainage; certain medications (steroids); eye trauma.
Intraocular pressure can be 3-5 mm Hg higher or lower in the morning? Higher
What has been proven to lower intraocular pressure? Aerobic exercise
How many people in the US have glaucoma? 2.2 million
How many of the people that have glaucoma know they have it? Half
What percentage of the people that have glaucoma in the US are blind? 12%
What is the second leading cause of blindness in the US? Glaucoma
What demographic is more likely to have glaucoma? African Americans
What age group is most likely to have glaucoma? People over age 60
Are family members of those diagnosed with glaucoma more likely to have it. Yes
People who are severely ______ are more likely to have glaucoma. Myopic (nearsighted)
Worldwide there are _________ suspected cases of glaucoma. 60 million
People with what disease are more likely to have glaucoma? Diabetes
What is the most common type of glaucoma? Primary Open Angle Glaucoma (POAG)
What percentage of people have POAG? 90 percent
POAG happens over a long period of time, true or false? True
What usually causes POAG? a slow clogging of the drainage canals (trabecular meshwork and Schlemm's canal)
Is POAG a lifelong condition? Yes
There are no ____ and no _________ with POAG. no pain and no symptoms
PAOG causes a loss of the....? visual field
Is POAG age related? Yes
What is a scotoma? Blind spot in your normal field of view
Age related intraocular pressure can be as high as... 30 - 35 mm Hg
What is acute glaucoma? Fast, closed angle glaucoma
Which is more severe, acute glaucoma or primary open angle glaucoma? Acute glaucoma
In acute glaucoma the iris bunches against the ______ and blocks the __________________ making the angle to small. cornea; trabecular meshwork
In acute glaucoma, a person can be fine until an event causes the pupil to open too widely. What can cause the pupil widen? 1) darkness; 2)shock/surprise
In acute glaucoma the pressure can rise past __ mm Hg within 30 min - 1 hr. 60
Which kind of glaucoma causes pain. Acute
What is a treatment for acute glaucoma? peripheral iridectomy
What is a peripheral iridectomy? Surgical cutting of a hole in the edge of the iris to allow for proper drainage of aqueous.
When is congenital glaucoma first present? At birth
Congenital glaucoma happens how often? Every 1/10,000 births
What causes congenital glaucoma? 1) hereditary; 2)abnormal development during pregnancy
Is secondary glaucoma open or closed angle? Can be either
What type of glaucoma is caused as a result of another disease? Secondary glaucoma
What are some things that cause secondary glaucoma? disease; trauma to the eye; tumor or clots in vascular system
What happens when pieces of pigment from the iris break off and clog the trabecular meshwork. Pigmentary glaucoma
What is normal tension glaucoma (NTG)? when the eyes have normal pressure, but the optic nerve is damaged.
All glaucoma results in damage to the...? optic disc
When patients have a thin cornea (less than 555 micrometers) it can result in...? artificially low intraocular pressure levels
Patients that have a thicker cornea may show...? an artificially high intraocular pressure level
What is used to measure corneal thickness using ultrasound waves? Pachymetry
What is non-contact tonometry (NCT)? uses a rapid air pulse to applanate (flatten) the cornea. Corneal applanation is detected via an electro-optical system.
What is applanation tonometry? The intraocular pressure is inferred from the force required to flatten a constant area of the cornea.
What is the middle layer of the eye? The uveal tract
What does the uveal tract consist of? Choroid; ciliary body; iris; crystalline lens
What is the choroid made up of? Dark brown tissue
The choroid contains ___ which gives it its dark brown color? melanin
What is melanin? A darkly colored pigment which helps the choroid limit uncontrolled reflections within the eye.
What causes red eye in pictures? The pigment in the choroid
The choroid contains how many layers? Five
How many layers of the choroid are vascular and how many are supportive? 3 vascular; 2 supportive
What are the five layers of the choroid? suprachoroid; vessel layer haller; vessel layer sattler; choriocapillaries; Bruch's membrane
What is the innermost layer of the choroid? Bruch's membrane
What are the two supporting layers of the choroid? Bruch's membrane and suprachoroid
How thick is Bruch's membrane 2 microns
What are the three layers of Bruch's membrane? Elastic layer; collagen; Pigmented epithelial
What contains all the capillaries of the choroid? Choriocapillaries
What are capillaries? Smallest blood vessels that serve as the connection between the arterial and veinal systems of the overall cardiac system.
What are arteries? Carry blood away from the heart; receive blood from the heart under alot of pressure
What are veins? Carry blood towards the heart; only receive the blood after it has traveled quite far from the heart; must be able to allow some collection of blood without bursting
What is the middle layer of choroid? vessel layer of sattler
What is the vessel layer of sattler made up of? many sizes of veins and some tiny arteries
Which layer of the choroid has a stroma? vessel layer of sattler
What is the stroma in the vessel layer of sattler made up of? collagen elastic fibers, blood vessels, and many melanocytes
What is the vessel layer of haller made up of? Large veins
What is the outermost layer of the coroid? Suprachoroid
Which layer of the choroid blends with the lamina fusca? Suprachoroid
Which layer of the choroid contains the ciliary arteries? suprachoroid
The retina will meet the choroid at the _________ before it ends. Ora serata
What happens to the Bowman's membrane at the limbus? It terminates
What nourishes the outer half of the retina? The choroid
Created by: griffiskr
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