Common Conditions Causing Vision Loss
Macular
Degeneration
Macular degeneration, most commonly
referred to as Age-Related Macular Degeneration (ARMD),
affects either a portion or all of the macula (area of
the retina responsible for central vision and “seeing”
fine details). Consequently, the central vision area
normally captured by that part of the macula becomes
blurred or is possibly seen as a dark spot.
Two forms of ARMD exist:
1)
Atrophic (DRY)
ARMD—approximately 80% of AMD patients have the dry
form. Quite simply, dry ARMD is the thinning of the
macula causing visual “holes” or deficits to appear in
central vision.
2)
Exudative (WET)
ARMD—In this less prevalent form of ARMD, fluid
collects beneath the retina resulting in varying degrees
of visual disturbance.
Diabetic Retinopathy
Diabetes causes disorders of the
circulatory system which can modify the tiny blood
vessels of the retina and make them very fragile.
There are three primary conditions
of diabetic retinopathy:
1)
Background
Retinopathy—The blood vessels are the first tissue
affected in this stage. Diabetic control is extremely
important in delaying or minimizing any impact on
vision.
2)
Macular Edema—This
condition occurs when the blood vessels leak fluid which
collects in the macula (responsible for detailed
vision). Diabetic macular edema is perhaps the most
common cause of decreased vision for diabetics.
3)
Proliferative
retinopathy—In this stage of the disease a
proliferation of new abnormal blood vessels begin
growing on the surface of the retina or optic nerve.
These vessels are prone to bleed and can cloud the
vitreous with blood. If left untreated, this condition
can lead to a partial or total vision loss.
Glaucoma
Primarily age-related, glaucoma
results when the optic nerve (the connection between the
eye and the brain) is damaged from increased pressure in
the eye. Usually,
this is caused by a blockage in the normal outflow of
the aqueous humor.
In a normal eye, constant pressure
is maintained by the fluid leaving at the same rate at
which it enters. When
the rate of outflow is impeded, pressure builds and this
can slowly cause damage to the optic nerve, which is
most often irreversible.
Three common forms of glaucoma
exist:
1)
Chronic—Gradual
and painless in nature, it is the most common.
2)
Acute—Strikes
suddenly and often painfully, it causes the cornea to
become cloudy.
3)
Congenital—Caused
by the malformation of the drainage system to the eye
prior to birth or in on infancy.
Brain Injury
A vision problem may result when
damage occurs to the visual system, anywhere behind the
eye to the seeing part of the brain. Sometimes loss of
eyesight stems not necessarily from eye damage, but
rather the brain’s inability to interpret the
information from the eye. Along with this type of loss,
peripheral vision loss can result from a brain injury.
Cataracts
The lens is the clear structure
behind the pupil which allows light to be focused on to
the retina. Should the clear lens become cloudy, visual
information passing through may be degraded resulting in
a decrease in vision. Because cataracts are often
directly related to normal aging, many doctors believe
that everyone will develop cataracts if they live long
enough.
Detached Retina
A portion of the retina can detach
from the back of the eye due to any number of unknown
events that impact the eye. If the retina remains
detached for a significant length of time, it can no
longer function properly, resulting in the loss of
varying amounts of vision.
Depending on the area of retina detached, prompt
surgery can minimize vision loss.
Retinitis Pigmentosa
This disease is due to the
degeneration of the retina’s photoreceptor cells which
are needed for peripheral vision and vision in dim
light. It is an inherited problem and often progressive
in nature. It begins with a loss of peripheral vision
and eventually can affect central vision. After many
years, total blindness may occur.