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Richmond Eye Associates
Eye Health and Disorders
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Introduction: Floaters, Flashing lights, Rainbows, Abnormal Color
Vision, Distorted Vision
This page discusses unusual visual phenomenon such as floaters and different types of
flashing lights. Other visual abnormalities such as seeing rainbows around lights,
abnormal color vision, and distorted vision are discussed as well.
The first grouping of abnormalities give symptoms of
floaters or flashing lights. Separate sections on
Rainbows,
Abnormal Color Vision,
Distorted Vision, and
Tunnel
Vision follow.
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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The vitreous is a gel-like fluid which fills most of the eye. As people age, this
vitreous becomes more and more liquefied. The vitreous has loose attachments to the
retina, and more firm attachments to the optic nerve. At some point in a person's life,
the vitreous liquefies enough to shift position in the eye. When this occurs, usually
between age 50 and 70, the back edge of the vitreous will pull forward away from the
retina, leading to a "vitreous detachment". This is generally a normal process,
although it may happen abnormally early in cases of high nearsightedness or trauma. As the
vitreous detaches, it tugs on the retina. This is perceived as a flash of light, similar
to a lightning flash in the corner of the vision. It may occur especially with eye
movement, since the vitreous moves in the eye. Debris pulled off of the optic nerve and
retina are then seen as floaters, suspended in the vitreous above the retina. Sometimes
this is described as a cobweb, a net, a string, or a fly over the vision.
These symptoms
usually resolve over a period of days to weeks, although some people will continue to see
the floaters for a longer period of time. The important thing is to determine that the
retina is healthy as the vitreous detaches. This requires a careful dilated examination of
the retina to look for tears, or other areas which may be at risk for tearing. A retinal
tear can then lead to retinal detachment, if not treated. Thus, people experiencing these
symptoms should be examined by an ophthalmologist as soon as possible. (Note, only about 1
in 10,000 cases of vitreous detachment lead to retinal detachment, but it still is one of
the most common causes of retinal detachment.)
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A tear in the retina can occur with vitreous detachment (see discussion above), with
trauma or eye injury, or in areas at risk for a retinal tear, such as "lattice
degeneration". The symptoms of a retinal tear usually are of a flash of light in the
peripheral vision followed by floaters. The floaters may be debris, but may also be blood,
if the tear extends through a retinal blood vessel. Symptomatic retinal tears should be
treated by laser to prevent
retinal
detachment. Sometimes a retinal tear is discovered incidentally as part of an eye
examination. These may or may not need to be treated.
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Uveitis refers to a large group of disorders which cause inflammation within the eye. A
similar condition,
iritis, usually
refers to an inflammation involving the front structures of the eye associated with pain,
redness, and sensitivity to light. In this discussion, uveitis could have these symptoms,
but mainly consists of inflammation involving the back structures of the eye (the retina,
choroid, and optic nerve). Inflammatory debris liberated into the vitreous leads to the
visualization of floaters. If this liberation continues, the vision may become
substantially hazy and blurred.
There are numerous conditions leading to uveitis, and
many have floaters and blurred vision as predominant symptoms: sarcoidosis, toxoplasmosis
chorioretinitis, ocular histoplasmosis, multifocal choroiditis, pars planitis,
endophthalmitis, syphilis, candidiasis, viral uveitis, Vogt-Koyanagi-Harada syndrome, and
HIV related uveitis.
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Eales' Disease is a rare disorder primarily affecting young adult males in their 30's to
50's. 80% of those affected are male, and usually both eyes are affected. There is no
known cause for the disease, and no known association with any medical disorder (although
one study noted balance dysfunction and hearing loss in 24% of patients).
In Eales'
Disease, there is inflammation of the retinal vessels, where there is visible sheathing of
the vessels and inflammation of the vessels. This can lead to obstruction of the vessels,
hemorrhages into the retina and vitreous, and occasionally retinal detachment (in severe
cases). There may be no symptoms of this disease, or one may see floaters, or develop a
loss of vision if vitreous hemorrhage or retinal detachment occur.
Treatment is usually aimed at eliminating the risk of hemorrhage through retinal laser
treatments. Oral anti-inflammatory agents may also be helpful.
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The entopic phenomenon is a normal phenomenon that some people may become suddenly aware
of. This sudden awareness may lead to the idea that there is a problem with the eyes, when
actually there is not. The entopic phenomenon can be seen especially when looking at a
bright blue sky. Small, rapid pin-point sparks of light can be seen darting about in the
central vision. Some people may think that these sparks are floaters. In reality, they
represent white blood cells moving through the blood capillaries of the retina. This is a
normal finding, and actually may indicate normal retinal function.
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Migraine headaches may be preceded by a visual "aura", lasting for 20 to 30
minutes, and then proceeding to the headache. Some people, however, experience the aura
but do not have a headache. This visual aura can be very dramatic. Classically, a small
blind spot appears in the central vision with a shimmering, zig-zag light inside of it.
This enlarges, and moves to one side or the other of the vision, over a 20 to 30 minute
period. When it is large, this crescent shaped blind spot containing this brightly
flashing light can be difficult to ignore, and some people fear that they are having a
stroke. In reality, it is generally a harmless phenomenon, except in people who
subsequently get the headache of migraine. Since migraine originates in the brain, the
visual effect typically involves the same side of vision in each eye, although it may seem
more prominent in one eye or the other.
Some people get different variations of this
phenomenon, with the central vision being involved, or with the visual effect similar to
"heat rising off of a car". Some people describe a "kaleidoscope"
effect, with pieces of the vision being missing. All of these variations are consistent
with ophthalmic migraine.
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Seeing rainbows around lights, especially at night, usually indicates swelling of the
cornea. This may occur from a variety of causes which are discussed under
Corneal Edema. Cataract can sometimes
cause this also.
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Color vision is perceived mainly by the macula, which is the central vision portion of
the retina. Thus any disorder affecting the macula may cause a disturbance in color
vision. However, about 8% of males and 0.5% of females have some version of "color
blindness" from birth. Usually this is an genetically inherited trait, and is of the
"red-green confusion" variety. The reds, browns, olives, and golds may be
confused. Purple may be confused with blue, and pastel pinks, oranges, yellows, and greens
look similar. Usually both eyes are affected equally.
There are many obscure macular
retinal disorders that can lead to a loss of color vision, and many of these syndromes are
inherited as well. There may also be a problem with a generalized loss of vision with
these problems as well. Other retinal problems can lead to a temporary disturbance of
color vision, such as
Central serous
Chorioretinopathy,
Macular Edema of
different causes, and
Macular Degeneration.
Certain types of cataract can gradually affect the color vision, but this is usually
not noticed until one cataract is removed. The cataract seems to filter out the color
blue, and everything seems more blue after cataract extraction. Optic nerve disorders such
as
Optic Neuritis can greatly affect
color vision, with colors seeming washed out during or after an episode.
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Distortion of vision refers to straight lines not appearing straight, but instead bent,
crooked, or wavy. Usually this is caused by distortion of the retina itself. This
distortion can herald a loss of vision in
macular
degeneration, so anyone with distorted vision should seek medical attention by an
ophthalmologist promptly. Other conditions leading to swelling of the retina can cause
this distortion, such as
Macular edema
and
Central serous
Chorioretinopathy.
An
"Amsler grid" can be supplied by an ophthalmologist so that the vision can be
monitored for distortion in people who may be predisposed to this problem.
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"Tunnel vision" implies that the peripheral vision, or side vision, is lost,
while the central vision remains. Thus, the vision is like looking through a tunnel, or
through a paper towel roll. Some disorders that can cause this include:
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Glaucoma - severe glaucoma can result in loss
of nearly all of the peripheral vision, with a small "island" of central vision
remaining. Sometimes even this island of vision can be lost as well.
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Retinitis pigmentosa - This is usually a hereditary disorder
which can be part of numerous syndromes. It is more common in males. The peripheral retina
develops pigmentary deposits, and the peripheral vision gradually becomes worse and worse.
The central vision can be affected eventually as well. People with this problem may have
trouble getting around in the dark. Cataract can be a complication as well. There is no
known treatment for this disorder, and supplements of Vitamin A have not been proven to
help.
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Stroke - a stroke involving both
sides of the visual part of the brain may wipe out nearly all of the peripheral vision.
Fortunately, this is a very rare occurrence
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