Tuesday, June 14, 2011

Can a Stroke Cause Blindness

A stroke can cause symptoms from hallucinations to complete blindness. These symptoms depend on where in the occipital lobe they occur.

When the stroke affects most of the occipital lobe on one side of the brain the result is called homonymous hemianopsia, the loss of half of the field of view on the same side in both eyes. This occurs frequently in stroke and brain injuries because of the connections and wiring of the wiring system in the brain.

Visual images on the right side travel from both eyes to the left side of the brain, while visual images on the left side in each eye travels to the right side of the brain. So damage to the right side of the posterior portion of the brain causes vision loss of the left viewing in both eyes. Damage to the left posterior brain causes a loss to the right field of vision.

Central vision is processed in the occipital pole in the brain. Central vision is what you see when you look straight ahead, the center of your vision.

A person affected in this area may have trouble looking straight in someone's face, they may not be able to see noses, upper lips, or the lower half of a person's eye on the affected side. They could however see the person's shoulder, and the top of their head on that side. These cases are rare, but when they do occur, they are referred to as, 'central visual defect'.

When the occipital lobes of the brain are completely affected by the brain it is called 'cortical blindness'. This is what we know as 'blindness', but doctors use this term to convey to each other the reason for the blindness stems from damage to the brain cortex.

People with cortical blindness also suffer sometimes from what is called visual Anosagnosia syndrome. This is a lack of awareness about a physical or mental impairment caused by damage to one or more parts of the brain. People with this anosagnosia are incapable of understanding that they have an impairment.

Other symptoms of occipital lobe stroke are visual illusions, visual hallucinations, visual agnosias, Balint syndrome which is the coming together of three symptoms because of a stroke at the border of the parietal and occipital lobes of the brain.

Symptoms of Balint syndrome are:

The inability to voluntarily look around in space.
  • Inability to grab an object while looking at it, due to an imbalance of eye and hand movements.
  • A tendency to only see one object in the visual field at one time.

Glaucoma Video

How to tell if you have Glaucoma

Glaucoma is an eye disease that affects the optic nerve in the eye.

Damaged Optic Nerve



The optic nerve receives nerve impulses from the retina and sends them to the brain, and these electrical signals gives us our vision. Glaucoma is damage to the optic nerve that generally begins with a gradual loss of side vision or the peripheral vision. Undiagnosed glaucoma and treatment can lead to blindness.

What Is Glaucoma

Glaucoma is usually associated with elevated pressure in the eye. This elevated pressure causes the eye to become harder and is what leads to damage of the optic nerve. Sometimes glaucoma occurs in normal eye pressure which ranges between 8mm and 22mm. This kind of glaucoma is caused by poor circulation of blood flow to the optic nerve.

Six million Glaucoma Victims

Glaucoma causes irreversible blindness. Six million individuals are blind in both eyes because of this horrible disease. In the United States, 3 million people have glaucoma, half of these people do not even know they have it. Not showing any symptoms they are unaware they have it, even when they lose their side or peripheral vision.

Sneak Thief of Sight

Glaucoma is referred to as 'the sneak thief of sight' because the intraocular pressure can build up and destroy vision without causing obvious symptoms. Awareness and early treatment can be successfully treated if caught early.

Who is at Risk

Everyone is at risk for glaucoma but certain people are at a higher risk, and these people need to be checked by their eye doctor more often.
  • diabetes
  • age over 45
  • Black ancestry
  • family history of glaucoma
  • history of high eye pressure
  • nearsightedness
  • history of injury to the eye
  • steroid use, either orally, injected or systematically
  • farsightedness (due to narrowed drainage angles which makes them susceptible to acute attacks of angle-closure glaucoma.)

Is Vitreous Detachment Dangerous

Almost a year ago I developed an eye condition in my right eye called vitreous aqueous detachment, the gel that surrounds the retina separated, or shrunk. Life after vitreous detachment has left me with rings, spots and the occasional light streak.

For months I had a blur in front of my right eye that is no longer there.

I do not work out of the home, but I do work hours on end at my computer at home. The ring in front of my right eye bounces gently back and forth. I am not usually conscious of the ring anymore, unless I purposely think about it, then I see it swinging back and forth as if it is being blown gently in the wind.

Is Vitreous Detachment dangerous? No it is not! But it is annoying.

The only way it becomes dangerous is when the retina tears, this then would require surgery.

Having vitreous detachment is a little more trickier for me as I am a diabetic, therefore it is essential that my eyes are checked annually for any changes in the eye. Keeping my blood sugar levels low is paramount for my diabetes to not affect my eyesight.

Once the optometrist dilates the pupils of the eye she can then see to the back of the eye, and she will be checking for damage to the retina because of high blood sugar and high blood pressure. Blood vessels in this area can become damaged by swelling and then weakened, possibly not letting enough blood through and then they can become clogged.

The doctor also checks to see if any scar tissue has formed, it has the ability to pull the retina away from the back of the eye, detaching the retina. A detached retina can cause blindness, and if this occurs and a lot of blood has leaked into the vitreous causing poor vision then surgery called vitrectomy would be necessary.

Being a diabetic makes me more susceptible for getting cataracts, a clear cloud that forms on the lens of the eye making everything look cloudy. Surgery would then be necessary to bring eyesight back.

The optic nerve is the eye's main nerve to the brain and the optometrist checks for glaucoma by looking for any damage caused by pressure building up in the eye. If I lose sight from the side of my right or left eye, then I am in big trouble, and only eye drops as a temporary measure may help or laser surgery.

So keeping my blood sugar levels and high blood pressure under control maintains my healthy eye condition of life with vitreous attachment.

Dangerous not a bit! Unless I ignore my diabetic health measures.

How to Tell if You Have Had an Eye Stroke

Anterior Ischemic Optic Neuropathy (AION) is a devastating disease that occurs in the middle aged and the elderly. It damages the optic nerve, and thus is called, 'a stroke of the optic nerve. Little warning is given as it strikes one eye, and can progress to the other eye later. A stroke of the optic nerve is not related to a stroke occurring in the brain so is not accompanied by any weakness or paralysis.

The optic nerve can be seen at the back of the eye in examination by the ophthalmologist, Made up of millions of nerve fibers blood vessels nourish the optic nerve with blood and nutrients. In a healthy optic nerve messages are sent to the brain resulting in vision. When the optic nerve is damaged, or its circulation is cut off, distortion or no vision is the result. How much vision is lost depends on how much damage to the optic nerve there is.

Ischemia of the optic nerve results in Ischemic Optic Neuropathy, this is a loss of blood supply to the tissues in the body decreasing oxygen and nutrition. Without nutrients nerves do not function and die.
There are two types of Ischemic Optic Neuropathy depending upon which part of the optic nerve is affected.

Anterior Ischemic Optic Neuropathy (AION)
This is caused by acute ischemia of the front(anterior) part of the optic nerve which is supplied by the posterior ciliary arteries.

Posterior Ischemic Optic Neuropathy (PION)
This is a less common type, and is caused by acute ischemia of the back (posterior) part of the optic nerve located behind the eyeball and this part is not supplied by the posterior ciliary arteries.

AION has two types depending on what causes it, Arteritic AION which is a serious type and is due to a disease called Giant Cell Arteritis or temporal arteritis. The second type is Non-arteritic AION a more common type with different causes but not associated with giant cell arteritis.

How AION is Diagnosed

The doctor will ask you some vital questions to determine which AION you have. In Non- Arteritic AION he may ask these questions to rule out non-arteritic AION. Painless, loss of vision due to AION may be the first symptom or complication of other diseases.
  • Was the vision loss sudden or gradual? If sudden what time of day was it discovered.
  • Any blurring or loss of vision before the actual vission loss, has it been stable since first discovering it, or improved or worsened.
  • Are you diabetic?
  • Any heart trouble, stroke, high or low blood pressure, or shock, recent heart surgery, cataract surgery, any excessive bleeding?
  • Any family history of glaucoma?
    Do you smoke, are you on any high blood pressure medication, if yes, which drug, how often and what time of day do you take it?
  • Are you on any birth control pills, or estrogen pills
Giant Cell Arteritis AION is a medical emergency because of the complication of visual loss in one or both eyes, which is preventable if diagnosis is early and treated immediately and aggressively with corticosteroids. This disease strikes those over 50 years or older, and is more common in women than men.
Eighty percent of persons with Giant Cell Arteritis will have felt unwell for some time. Twenty percent have no general symptoms and are healthy. Some patients experience, 'euphoria or well-being,' while they are unconcerned about their vision loss and may insist they see well when it is clear they can't. They may even refuse treatment so it is important for family support to convince them they need help.

Signs to Look For

If Giant Cell Arteritis is present the physician will want to know about these problems.
  • Pain while chewing food, loss of appetite, weight loss, pain in the temples and neck
  • Scalp tenderness, headaches, fatigue, sleepiness, muscular aches and pains
    The opthalmologist needs to know how much the patient can see at every visit, to see if any changes have occurred. Plus reading the eye charts for distance and near visual acuity, the patient will often have visual field testing.

Visual field testing:
This test measures both straight ahead and side vision. A defect in the visual field test shows which optic nerve fibers are affected by the disease. A normal eye (20/20) visual acuity can have visual field loss in the periphery, so a normal visual acuity does not determine no visual loss.
    Relative Afferent Pupillary Defect The pupil of the eye gets larger and smaller according to the amount of light, the optic nerve reacts to light. If the pupil is constricting to light less than normal it shows there is damage to the optic nerve. Pupils are tested by shining a light into each eye causing them to constrict, as the light is moved between the eyes the pupil should constrict to the same size. If this doesn't happen then a relative afferent pupillary defect is present in the affected eye.
    Glaucoma Testing Pressure in the eye is measured with a tonometer, it is a painless procedure that is essential to obtain information about the circulation in the eye. A person may not know they have high pressure in the eye until they have experienced visual loss. Fundus Photograph and Fluorescein Fundus Angiography This is a routine dye test to determine the state of circulation, or the amount of swelling in of the optic disc and its resolution.

 

Monday, May 30, 2011

Adjusting to Life After Vitreous Detachment

Last year I suffered an eye condition called vitreous detachment, the gel that surrounds the lens in my right eye separated and shrunk or disappeared.

I was out walking my dog, Sheba when I suddenly noticed what I thought was a whole lot of bugs swarming in front of my face. I kept swatting them away, but to no avail, they insisted on bugging me. I absently thought to myself, I guess it's going to rain, that is why all the bugs are out tonight.

I finished walking Sheba and took her in the house, noticing that the bugs were not going away from in front of my face. Light flashes and white dots accompanied what looked like spider webs and a ring kept jumping around on the right side of my vision. I was scared, as I had never experienced anything like this in my life.

I went to the hospital where the eye specialist underwent an extensive exam on my eye. I never like going to the optometrist at any time, but the necessity of getting one's eyes checked is enhanced for me because of my diabetes.

At the end of the examination he told me that I had vitreous detachment in that eye and then he proceeded to tell me the gruesome facts about the eye condition. He told me that it comes with advancing age, I was 56 at the time, and if old age brings it on, then I am an old 56.
When the medical world doesn't know the cause of something, they either blame it on old age or a virus.

Today one year later I have noticed some changes to my eyes. I love to read, but it just is not the same any more. I have to approach reading a little different now.

If I read too long, the words on the page become completely blurry, and I have to stop to rest my eyes for awhile until my normal vision comes back. I look at my surroundings around me and everything is blurry too.

Life after vitreous attachment is different now, yes, it is discouraging, but at least I still have my vision, thank God, He is merciful. It could have been worse, instead of the gel separating, the retina could have torn, and then I would have needed surgery.

A minor adjustment in life's road, having taken a detour from the path but, I am managing to find my way back and work with what I have.
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