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46 Cards in this Set

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What 2 chambers are connected and continuous via the pupil?
Anterior and Posterior Chambers
What structure connects the anterior and posterior chambers of the eye?
Pupil
Contrast the fluid pressure in the anterior chamber with the fluid pressure in the posterior chamber.
Fluid pressure in each chamber will be the same, since the chambers are connected via the pupil.
Describe the journey of a typical humor molecule.
Production by ciliary bodies-->fluid flows around lens-->through the pupil-->into the anterior chamber-->trabecular meshwork-->canal of Schlemm
What is the pressure when the ciliary body cannot push with enough force to release any more fluid?
50-70 mmHg
What is the point of equilibrium for IOP and is it the same for everyone?
50-70 mmHg, fair amount of variation b/w individuals in what is "normal"
When the equilibrium pressure is reached (50-70 mmHg), the IOP is greater than what?
Perfusion pressure in the retinal capillaries
When the IOP is greater than the perfusion pressure in the retinal capillaries, what happens?
Results in a loss of blood flow which causes cells in the retina to die.
What does the increase in IOP do to the optic nerve?
Causes compression of the optic nerve which results in the death of fibers within the nerve.
How does disk cupping occur?
Normally, examining the optic disk you will see just a slight "pit" but as nerve fibers die, the spaces left where those fibers used to reside cause the pit to appear larger and start to look hollow.
Is disk cupping the direct result of the death of nerve fibers or pressure pushing on the disk?
Direct result of the death of nerve fibers
What is the word for a small visual field defect?
Scotoma
Are the effect of glaucoma reversible or irreversible?
Irreversible: Screening for glaucoma is very important, damage done can not be preserved.
What is the magic # for IOP?
21 mmHg
What percentage of the population will have an IOP above 21 mmHg?
2%
IOP varies by 4-5mmHg depending on what?
Time of day
What are other factors that cause IOP to vary?
Age, sex, state of hydration
Is an elevated IOP alone enough to make a diagnosis of Glaucoma?
NO
Does the absence of elevated IOP necessarily rule out Glaucoma?
NO
What 3 things are used for the diagnosis of glaucoma?
1.IOP
2.Visual field measurement
3.Optic disc cupping
What 3 methods are used to measure IOP?
1.Goldmann Applanation Tonometry (preferred method)
2.Schiotz Indentation tonometer
3.Non-contact (air-puff) tonometry
This method uses a tool, which is mounted to a slit lamp. This presses against the eye and measures the force required to flatten out a constant area of the eye. P=f/a. So this toll would give us the IOP. This is the method preferred by most ophthalmologists. What instrument is used?
Goldmann Applanation Tonometry
This is the older version of the Goldmann Applanation Tonometer. The difference is that there is no slit lamp involved and instead the patient lies supine and a weight is set directly on the eye and the indentation is measured. This is less accurate than the previously mentioned method. If you ever use this method, you want to rest your finger on the face somewhere, making sure that you are not pressing on the weight, or the eye itself. What instrument is being used to measure IOP?
Schiotz Indentation Tonometer
This method uses a quick burst of air to flatten, or applanate, the cornea. These instruments are expensive and less accurate than Goldman Applanation, but they are often available in hospitals and redicare facilities. What instrument is used?
Non-contact (air-puff) tonometry
What 3 methods can be used to test the visual field?
1.Tangent Screen
2.Goldmann Perimetry
3.Automated Perimetry
What are some clues that a patient might have optic disc cupping?
Look for dyssymmetry in the optic disk margin, as well as differences between the patients disks. These can be clues that there may be some cupping going on.
What does the location of the damage (cupping) to the optic nerve help predict?
Helps predict where the visual field defect will be.
Switching the ophthalmoscope to the what light may help one see the retinal defects?
Green light
What are 2 additional diagnostic modalities for Glaucoma?
1.Inspection of the corneal-scleral angle
2.Family History
Inspection of the corneo-scleral angle. This is done by placing a lens over the eye that has a mirror on it. The mirror allows you to see into the corner of the eye, which otherwise would not be visible. Visualizing the corneosclearal angle allows the practitioner to see if there is an anatomical blockage of the trabecular meshwork. What technique is this?
Gonoscopy
What is the epidemiology of glaucoma?
Most commonly seen in elderly patients
Green topped bottles mimic what system?
Parasympathetic-->constricts the pupil
Red topped bottles mimic what system?
Sympathetic-->Dilates the pupil
What is the major systemic effect of beta-blocking drugs to treat glaucoma?
Bradycardia
What is a side effect of epinephrine?
Occular irritation and redness
Depletion of serum potasssium, lowering of the bld pH, appetite loss, paresthesia, and aplastic anemia. What drug causes these side effects?
Oral carbonic anhydrase inhibitors
These drugs have side effects such as increased blood volume, heart failure, epidural bleeds, and diuresis. However, they lower the IOP fast! This is not used for chronic control of glaucoma, but rather for acute glaucoma. What drug causes these side effects?
Hyper-osmotic Agents
What is the purpose of Laser Trabeculoplasty?
Used to burn holes the trabecular meshwork, opening it up.
What was the method for opening up a hole in the trabecular meshwork, prior to laser technology?
Surgical Trabeculectomy
What unaccepted treatment helps lower IOP?
Medical Marijuana
This type of glaucoma is PAINLESS, slowly progressive and may present with only progressive loss of vision in the advanced stage of the disease. Diagnosis is dependent upon good screening, as once visual problems are present, they can not be repaired. What type of glaucoma?
Open Angle Glaucoma/Chronic Simple Glaucoma
This is a sudden painful elevation of IOP is response to stress or pupil dilation. Other symptoms will include decreased visual acuity, fixed 4-5mm pupil which does not react to light, red conjunctivea and hazy cornea, possible n/v. What type of glaucoma?
Acute Angle Closure Glaucoma
What types of patients are most vulnerable to angle-closure glaucoma?
Very far-sighted people and those of Asian descent
What type of glaucoma is treated by an emergency procedure that involves burning a small hole through the outside edge of the iris? This is typically done with a a laser, but in the past was done surgically. This allows fluid to flow through the iris and into the angle, relieving the pressure.
(Acute) Angle Closure Glaucoma
This is bad news and needs to be diagnosed and treated within the first few days of a newborn's life. If the problem is NOT fixed within the first few days the child will likely have permanent visual defects. These babies will appear to have very large eyes (buphthalamia). Other signs include light sensitivity noted when you shine a light in their eyes. What type of glaucoma?
Congenital Glaucoma
This type of glaucoma is mainly due to the use of certain medications, specifically those that contain steroids. 5-10% of patients that are treated with steroids will develop glaucoma. Other causes of secondary glaucoma include injury, vein occlusion, or a number of other diseases. What type of glaucoma?
Secondary Glaucoma