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