Low vision,
partial sight or sub-normal vision is defined as an impairment to central
or peripheral vision, uncorrectable by conventional lenses or surgery,
which leads to impaired performance. Thus blurred vision from cataracts
is not low vision since surgery can restore useful sight. Reduced visual
acuity from macular degeneration however is low vision, since irreversible
damage can occur to the retina which cannot be improved with conventional
glasses.
Macular
degeneration, glaucoma, diabetic retinopathy, retinitis pigmentosa, and
traumatic injury are among the leading causes of low vision.
Some causes
of low vision can be treated in their early stages. A person at risk for
retina damage from diabetes can have laser photo coagulation of the peripheral
retina to prevent central vision loss. The so called "wet" form of macular
degeneration (where new blood vessels grow under the retina and distort
vision) can benefit by laser treatment depending on the location of the
blood vessels. The "dry" form of the disease is not treatable although
it progresses more slowly.
Both
forms of age related macular degeneration (AMD) have been shown to progress
more slowly when patients took zinc with anti-oxidant vitamins such as
A, C, and E. Commercially available products include Ocuvite Extra and
I-Caps. A prepared combination is preferred to buying each component vitamin
separately since the effect on other nutrients is taken into account. For
example zinc interferes with copper metabolism so if you didn't take supplemental
copper at the same time you would be doing yourself a disservice.
RheoTherapy
is a new experimental treatment using aphoresis technology. This procedure
involves removing certain components from the blood plasma and returning
the "cleansed" fluids to the body. Our office will be assisting in the
data collection for patients traveling to Florida for this controversial
new procedure. The information gathered during the post procedure examination
period will hopefully lead to better guidelines for who may benefit from
this technique. Currently the center is reporting an improvement in approximately
one line of visual acuity, so this may be an option for people with early
forms of the disease..
Magnification
is the key to restoring functional vision for low vision patients. Function
is the key here, not clarity. An example of restored function is if a patient
can no longer read news print, but can read the headlines, by magnifying
the print in an article to the size of headlines the patient can then read
the newspaper. It is a challenge and takes some practice, but it is possible
in many cases.
Magnification
can be achieved by high powered bifocals, hand held or stand magnifiers,
telescopes or closed circuit television. All forms of magnification
have a limiting problem in that the larger the image, the smaller the field
of view. Therefore the least amount of magnification that lets you achieve
the desired goal is preferred.
One of
the newest innovations in magnification is the Auto focus VES telescope
by Ocutech .
For patients who have responded well to magnification but were limited
by a device which was focused for a single distance, or having to manually
adjust the focus, the Auto focus telescope has worked well.
Mounted
on the top of a spectacle frame, the Auto focus is best used as a sighting
device. While it is possible to read with it, that is a challenging task
since it is a head mounted device. It is more suited to identifying your
gate number at the airport, the items in a particular row at the grocery
store and individual item prices.
The
Auto focus gives 4X magnification. In other words if your vision is 20/80
on the eye chart, you would be able to see the 20/20 line! If your vision
is 20/200 you could see 20/50. As reference, the California Department
of Motor Vehicles requires 20/40 for a drivers license.
From
a more practical standpoint, if you can recognize faces at 3 feet, with
the Auto focus you could recognize them at 12 feet. If you can see your
playing cards at 4 inches, you could see them at 16 inches. If you cannot
achieve a particular task at any distance, the auto focus will not
let you achieve it either.
One of
the most useful devices is your own television set! With a special attachment
you can read the newspaper, write checks, or read your mail all on your
TV screen. And the print is as big as newspaper headlines--even bigger
if you want. Magnification up to 24X on a 13 inch screen--48X on a 25 inch
screen!
Please submit any questions or comments to: wbarrod<at>drbarr.com
