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Richmond Eye Associates
Eye Health and Disorders
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Introduction: Loss of vision
A loss of vision can be a frightening experience, and all people with a sudden loss of
vision should be seen by an ophthalmologist as an emergency. Here, loss of vision refers
to a severe blurring of the vision in one or both eyes often to the point that almost no
detail can be made out. There may be large blind spots in the vision, or the appearance
that something is blocking the vision. With these symptoms, there is almost always a cause
for the visual loss other than a simple change in glasses.
Many things that cause blurred vision can also cause a loss of vision,
if the condition is severe enough. These conditions are discussed on the
Blurred Vision page. Many other eye problems can cause a loss of
vision along with other symptoms. Links to Symptom and Diagnosis pages based on these
other symptoms are included as well.
Read this important information
before proceeding further:
These sections are not intended to replace the professional examination and
diagnosis by a physician, and they are presented here purely for informational purposes.
All possible diagnoses and treatment options are not covered, and the information
discussed should not be taken as a recommendation to self-diagnose and self-treat a
condition. A misdiagnosed or improperly treated eye condition can result in a permanent
loss of vision, or a permanent loss of function of the eye or visual system. In the case
of any eye problem, seek medical attention promptly. This can include emergency room
treatment, as well as treatment by a medical physician or eyecare provider.
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Conditions Discussed on this Page:
For eye anatomy explanations, go to
ANATOMY
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Amaurosis fugax refers to a temporary black-out of vision. This is usually affects one
eye, is painless, and is often described like a "shade coming down over the
vision" of that eye. The black-out may last minutes, and then the vision returns. The
problem can recur in the future, and could affect either eye. Most commonly, this happens
in older people with arteriosclerosis and possibly vascular disease, and is due to small
clots breaking off of the walls of arteries and then lodging in the vessels of the eye.
The clot obstructs the blood flow to the retina, and the vision blacks-out.
When the clot
breaks up, the blood flow returns, as does the vision. The source of the clot (or embolus)
is usually from the carotid arteries leading up the neck to the brain, or from the heart.
The embolus may be a cholesterol crystal, a calcium deposit, or a true blood clot. This
problem falls into the same category as "transient ischemic attacks" (or TIA's),
which may herald a stroke. Vascular evaluation and possibly anticoagulation (use of blood
thinners) is indicated for this problem.
Other problems which cause a temporary loss of
vision include:
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Obstruction of the vertebral arteries, which course up the back of the neck and supply
the visual part of the brain. People which this problem may notice temporary dimming of
vision affecting both eyes, and possibly imbalance.
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Increased intra-cranial pressure (the pressure of the fluid around the brain) can cause
momentary lapses of vision especially when moving, such as standing from a sitting
position. Sometimes even eye movements are enough to induce a temporary loss of vision.
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Retinal migraine is a spasm of the artery leading into the eye which supplies the
retina. This spasm can lead to a temporary black-out of vision on one side, and is fairly
rare.
Return to Condition List
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If a clot (embolus) breaks free from the wall of a blood vessel leading up the neck or
to the eye, it can lodge in the retinal arteries causing an obstruction of blood flow to
the eye, and a loss of vision. In some cases, the clot will rapidly dislodge, and the
vision will return (Amaurosis fugax, discussed above). However, if the clot is large it
may not dislodge, and the vision remains blacked-out. Usually this is painless, and the
loss of vision is severe. If the blood flow to the retina is interrupted for more than 1
1/2 hours (approximately), the vision may not return even if the clot breaks free and the
circulation is restored. This condition may indicate risk for cardiac disease, and stroke.
If a person with this condition rapidly seeks the medical help by an ophthalmologist,
things may be able to be done to dislodge the clot before permanent damage occurs. No
ophthalmologist will turn a patient away with this condition.
Return to Condition List
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The retinal blood circulation is drained by a single vein, called the central retinal
vein. If this vein becomes obstructed, various problems can occur in the eye, depending on
the severity of the obstruction. A person with this condition will notice blurring of
vision, dimming of vision, and possibly blind spots and floaters in the vision. It usually
starts fairly suddenly, but the vision may worsen over a period of time (hours to days).
Rarely does this happen in both eyes at the same time. The problem is usually caused by
underlying vascular disease, and sometimes abnormal clotting or blood thickness. It is not
caused by clots breaking off of arteries, like an artery obstruction is.
There is no
effective treatment to reverse the blockage of the vein, except to treat any underlying
medical condition (diabetes, hypertension, increased cholesterol, etc.), and hope that the
vein opens back up on its own. About 1/3 of cases will completely resolve with little
damage to the vision. About 1/3 stay the same with some loss of vision, and 1/3 of cases
worsen and develop more severe loss of vision. The worst cases may need to be treated by a
laser to prevent a dangerous form of glaucoma (neovascular glaucoma), but the laser
treatment will not help the vision. Studies are being done to evaluate possible medication
or laser treatments which may help people with this condition. (For a related topic, see
Macular Edema.)
Return to Condition List
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A stroke is an obstruction of blood flow leading to a part of the brain. If the part of
the brain affected serves the vision, there may be a loss of vision with the stroke. If a
small area of brain is affected, there may be a blind spot in the vision corresponding to
that area. However, with more substantial stroke, an entire side of vision can be lost.
The visual part of the brain has a left and right side. The left side serves the right
half of the vision from both eyes, and right side serves the left half. Thus if there is a
stroke of one side of the brain, the person may lose the corresponding half of vision of
both eyes. Most people notice this more from the eye that lost the outside field of
vision. (For example, a stroke of the left side of the brain would cause the right half of
vision to be lost from both eyes. This would be the inside half of vision of the left eye,
and the outside half of vision of the right eye.)
Strokes affecting the visual part of
the brain are treated as any stroke of the brain, and usually the problem is evaluated by
internal medicine physicians, or neurologists.
Return to Condition List
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Some people develop a degeneration of the part of the retina that serves the central
vision (reading vision), which is called the macula. Unlike macular degeneration, where
there is gradual deterioration of the macula possibly associated with hemorrhage under the
retina, a macular hole is a sharply outlined loss of retina in the center of the macula.
It is not fully understood why this happens. There may be some risk for the second eye
being affected as well. Usually there is a fairly severe loss of reading vision (central
vision), with a blind spot appearing centrally. The peripheral vision remains normal.
There is a surgical procedure which may help some macular holes to fill back in, with some
return of vision.
Return to Condition List
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A retinal detachment occurs when fluid in the eye gets behind the retina, and lifts it
off of the wall of the eye on the inside. Normally the fluid in the eye has no way to get
under the retina, but if a tear in the retina occurs, a detachment could follow. A retinal
detachment is usually perceived as a dark area encroaching on, or covering, the central
vision from the outside. The symptoms may seem to occur suddenly, or may worsen over a
short period of time. A retinal detachment including the macula (the central visual part
of the retina) will cause a substantial loss of vision. Retinal detachments can be
repaired surgically with usually good results, depending on the severity of the
detachment, how long it has been present, and if the macula is involved or not.
People
who are highly nearsighted may be at increased risk for retinal detachment, as are people
who have had eye trauma. There are certain conditions of the retina which lead to
detachment in the future, and sometimes these are treated prophylactically. The most
common of these is a retinal tear, and symptoms of retina tear usually precede a
detachment (floaters and flashing lights). A person with these symptoms should be examined
promptly by an ophthalmologist. (See
Retinal
Tear for more information.)
Return to Condition List
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Bleeding into the eye can cause substantial loss of vision, since the blood clot
obstructs light images from reaching the retina. The main cavity of the eye is filled with
a gel-like substance called vitreous, and bleeding into this is a "vitreous
hemorrhage". Blood becomes trapped in this gel, and does not immediately sink to the
bottom of the eye or dissolve. Thus, symptoms usually include seeing floaters or spots in
the vision which increase with time (and possibly flashing lights). With more severe
hemorrhages, a dark, reddish blob which seems to move, may cover the vision. Most vitreous
hemorrhages will resolve spontaneously with time, although some need to be removed
surgically. The most important thing is determining the cause of the hemorrhage. The
bleeding can occur with the following conditions, some of which are discussed elsewhere:
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Retinal tears
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Vitreous detachment - a separation
of the gel-like vitreous from the retina inside the eye.
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Diabetes - as a complication of
vascular growth within the eye.
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Macular degeneration - with a severe
hemorrhage under the macula breaking through the retina, and bleeding into the vitreous.
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Retinal Vein obstruction
- with bleeding from abnormal blood
vessels growing in response to the vein obstruction
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Sickle-cell disease - this blood disorder can cause retinal vascular problems which may
lead to vitreous hemorrhage.
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Valsalva related vitreous hemorrhage - severe straining can raise the venous pressure
around the eye high enough to cause a vitreous hemorrhage. This can also occur with
trauma.
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Return to Condition List
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Cataract - a severe cataract can
cause more than just blurred vision. Some cataracts cause a loss of vision under glare
circumstances.
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Corneal abrasion - A centrally
located abrasion can cause a loss of vision. Others symptoms are pain, tearing, redness,
and a sensation that something is in eye.
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Corneal ulcer - an infected cornea can
sometimes cause a loss of vision along with pain and redness.
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Glaucoma (acute) - pain, blurred
vision, rainbows around lights. Severe chronic glaucoma can also cause a loss of vision
over time.
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Iritis - pain, sensitivity to light,
blurred vision or a loss of vision.
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Macular Degeneration - severe
macular degeneration leaves a scar or hemorrhage in the retina, causing a loss of vision.
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Optic Neuritis - this can cause
sudden blurred or lost vision, and sometimes pain on eye movement.
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Orbital cellulitis (infection) -
infection of the orbit behind the eye can lead to blurred or double vision, pain, and eye
protrusion.
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Scleritis - pain, blurred vision,
redness.
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Temporal arteritis - headache with
blurring or loss of vision, usually in the elderly.
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Thyroid related eye disease -
scratchy sensation, double or blurred vision, protruding eyes.
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Uveitis - inflammation within the
eye can lead to floaters, pain, and blurred vision. Severe inflammation can cause a loss
of vision due to inflammatory debris within the eye.
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