OCT Flashcards
What is OCT?
Optical coherence tomography (OCT) is a non-invasive imaging test. OCT uses light waves to take cross-section pictures of your retina.
With OCT, your ophthalmologist can see
each of the retina’s distinctive layers
OCT showing each distinctive layer of the retina, allows your ophthalmologist to
map and measure their thickness. These measurements help with diagnosis. They also provide treatment guidance for glaucoma and diseases of the retina.
Age-related macular degeneration (AMD) is a problem with your retina. It happens when
a part of the retina called the macula is damaged.
With AMD you lose your
central vision
with AMD, you cannot see
fine details, whether you are looking at something close or far. But your peripheral (side) vision will still be normal.
AMD is very common. It is a leading cause of vision loss in
people 50 years or older
About 80% (8 out of 10) of people who have AMD have the ____ form.
dry
Dry AMD is
when parts of the macula get thinner with age and tiny clumps of protein called drusen grow. You slowly lose central vision. There is no way to treat dry AMD yet.
Wet AMD is when
new, abnormal blood vessels grow under the retina. These vessels may leak blood or other fluids, causing scarring of the macula
You lose vision faster with ____ AMD than with ___ AMD.
You lose vision faster with wet AMD than with dry AMD.
Many people don’t realize they have AMD until
their vision is very blurry.
You are more likely to develop AMD if you:
eat a diet high in saturated fat (found in foods like meat, butter, and cheese) are overweight smoke cigarettes are over 50 years old have hypertension (high blood pressure) have a family history of AMD
Right now, there is no way to treat the dry form of AMD. However people with lots of drusen or serious vision loss might benefit from taking
a certain combination of nutritional supplements. people may slow their dry AMD by taking these vitamins and minerals daily: Vitamin C (500 mg) Vitamin E (400 IU) Lutein (10 mg) Zeaxanthin (2 mg) Zinc (80 mg) Copper (2 mg)
To help treat wet AMD, there are medications
called anti-VEGF drugs. Anti-VEGF treatment helps reduce the number of abnormal blood vessels in your retina. It also slows any leaking from blood vessels. This medicine is delivered to your eye through a very slender needle. Laser surgery may also be used to treat some types of wet AMD. Your eye surgeon shines a laser light beam on the abnormal blood vessels. This reduces the number of vessels and slows their leaking.
People with diabetes can have an eye disease called diabetic retinopathy. This is when
high blood sugar levels cause damage to blood vessels in the retina. These blood vessels can swell and leak. Or they can close, stopping blood from passing through. Sometimes abnormal new blood vessels grow on the retina. All of these changes can steal your vision.
NPDR (non-proliferative diabetic retinopathy)
This is the early stage of diabetic eye disease. Many people with diabetes have it.
With NPDR, tiny blood vessels
leak, making the retina swell. When the macula swells, it is called macular edema. This is the most common reason why people with diabetes lose their vision.
Also with NPDR, blood vessels in the retina can close off. This is called
macular ischemia. When that happens, blood cannot reach the macula. Sometimes tiny particles called exudates can form in the retina. These can affect your vision too.
PDR (proliferative diabetic retinopathy)
PDR is the more advanced stage of diabetic eye disease
Papilledema is
the swelling of the optic nerve as it enters the back of the eye due to raised intracranial pressure
When you have a headache or unexplained nausea and vomiting, your doctor will look into your eye with an ophthalmoscope. Changes in the appearance of the optic nerve and the blood vessels that pass through it can be seen through the ophthalmoscope and might be related
to the source of your symptoms. The anatomy of the optic nerve makes it a sensitive marker for problems inside the brain.
optic nerve’s whole surface is bathed in cerebral spinal fluid. This fluid protects
the nerve from sudden movement.
even slight increases in the pressure of this fluid, from swelling of the brain, can compress the optic nerve around its whole circumference in a
“choking” manner
When the optic nerve is exposed to high pressure, or when it develops inflammation on its own, it can .
bulge into the back wall of the eyeball, causing papilledema
The term papilledema ideally should be reserved for
swelling of the nerve head when the swelling is caused by elevated intracranial pressure. Other conditions can have a similar appearance to papilledema caused by high intracranial pressure.
Some important causes of increased pressure from cerebral spinal fluid and papilledema are
brain tumors and brain infections, such as a brain abscess, meningitis or encephalitis.
A significant proportion of people who are diagnosed with brain tumors have some evidence of
papilledema.
One condition can cause increased pressure in the cerebral spinal fluid without associated swelling of the brain or ventricles. This condition, called idiopathic intracranial hypertension or pseudotumor cerebri, is caused when
the body makes too much spinal fluid. It is more common in women who are obese and of childbearing age. The condition seems to be triggered at times that the body is adjusting to hormone changes, such as pregnancy, the start of birth control pills, the first menstrual period, or menopause.
Symptoms related to papilledema caused by increased pressure include
headache and nausea with vomiting and a machinery-like sound.
Twenty-five percent of people with advanced severe papilledema also will develop some visual symptoms. Typically, the visual changes are
recurring brief episodes lasting less than 30 seconds in which the vision turns gray or blacks, sometimes described as if a veil has fallen over the eyes. The symptoms usually affect both eyes at once. Visual blackouts often are triggered by a change in position, such as by standing up very suddenly, or they may be triggered by coughing or straining in the chest or abdomen. Occasionally, people with papilledema can have an experience of flashing lights, often seen in an arc shape. Other visual changes occur over time, including a smaller field of vision with a larger blind spot and, ultimately, blindness, if successful treatment is not given.
If the optic disc appears elevated and has a blurred outside edge, your doctor can diagnose
papilledema
The pressure within the nerve can cause the draining veins in your eye to become
congested
When papilledema is severe,
small red spots from local bleeding or spotty color changes on the retina from accumulated debris or from damaged retina cells may be seen
Papilledema causes each eye to have
a wider blind spot near the nose, and it narrows the peripheral (edge) vision
After the cause of papilledema is identified and treated, and any pressure increase in the spinal fluid has returned to normal, optic disk swelling gradually will go away over
six to eight weeks
