By Bill Takeshita, O.D., F.A.A.O., F.C.O.V.D.
Low vision optometrists and ophthalmologists are doctors who design
and prescribe specialized glasses and visual aids to help people with
vision impairment to use their remaining vision maximally to read,
write, and perform daily tasks. Nine out of every 10 people with vision
impairment have functional vision that can be improved with optical and
electronic visual aids. Unfortunately, many people with macular
degeneration, diabetic retinopathy, glaucoma, and retinitis pigmentosa
have not been referred to a low vision doctor for a low vision
examination to be fit with specialized glasses. For millions of people
with low vision who can no longer read with their magnifiers, low vision
doctors can help them to read again.
A low vision examination is very different from a general eye
examination. The purpose of the examination is not to inspect the
tissues of the eyes again, but rather to determine ways to maximize the
patient’s vision and provide solutions for the patient. The examination
begins with the doctor speaking with the patient to understand the
specifics about the desired goal. For example, if a pastor asks the
doctor for help reading the Bible, the doctor must also spend time to
know what size print is in the Bible, what distance the pastor will be
holding the Bible from the eyes, what level of lighting is available,
and other details so that he or she may customize a pair of glasses that
will serve the pastor’s needs. Next, the doctor inspects the tissues of
the eye and measures the central and peripheral vision to determine
which region of the retina has the best function. For many people with
macular degeneration, the central region of the retina often has scar
tissue and the doctor will design glasses to help the patient use the
peripheral regions of the retina. Conversely, for patients with glaucoma
or retinitis pigmentosa, the peripheral vision is often reduced and the
doctor will design visual aids to maximize the central vision.
A test called low vision refraction is performed to focus the light
onto the desired region of the retina. Prism lenses and peripheral
retinal locus (PRL) training may also be used to teach the patient how
to use the healthier region of the retina to read. As simple as it
sounds, it is often very difficult for people with low vision to do this
on their own because they have used their eyes in a specific way for
all of their life. To train a different region of the eye to read takes
time and practice.
The low vision doctor performs many other tests to measure whether
the patient can see some colors better than others, whether or not the
patient can see faded print, and what levels of lighting maximize
vision. Other tests are performed to determine the patient’s ability to
move the eyes from left to right in a reading pattern, keep the eyes
steady on the word being read, ability to focus the eyes together as a
team, and the best distance to focus on the reading material. All of
this information is used to design a pair of glasses that magnifies the
print, increases the contrast, and deflects the words on the healthier
regions of the eye for optimal reading.
One of the most common questions asked by patients is, “Can you make a
pair of glasses that is the same power as my hand magnifying glass?”
The answer is yes. Low vision optometrists and ophthalmologists can
create specialized glasses that provide high levels of magnification
that also incorporate the patient’s prescription needs. Colored tinted
lenses can be used to increase the contrast of the print, helping people
who have difficulty reading the gray ink on a newspaper more easily.
Special anti-reflective coatings can be placed on the lenses to reduce
glare and increase the brightness of the text while miniature telescopes
can also be inserted into the lenses to help people to read at various
distances. These telescopic glasses can be very helpful for musicians
who have blurred vision and need to read sheet music from a distance of
three feet. Glasses that used to look like "Coke bottles" can now be
made thin and lightweight with excellent optics.
After the glasses have been designed, the doctor will teach the
patient how to use the special reading glasses. This is a very important
but overlooked step that is critical for successful reading. The
patient must know whether to hold the print on his or her right or left
side, what distance from the eyes, what type of light bulb to use, where
to position the light, and how long to read each day. In some cases,
the doctor will provide exercises to teach the patient how to use the
healthiest region of the retina for reading.
People with more advanced or severe vision impairment will often
benefit from using low vision glasses in conjunction with other visual
aids. The combined use of reading glasses with magnifiers and electronic
visual aids will allow many people with low vision to read again.
In summary, it is important for people with low vision to remember
that specialized low vision glasses can improve the reading ability of
the majority of people with vision impairment. Optometrists and
ophthalmologists who specialize in low vision perform specialized tests
to design glasses and visual aids to maximize the vision of people with
low vision and can even help the legally blind to read.
For more information on finding a low vision optometrist or
ophthalmologist in your area, call Braille Institute for a referral at
1-800-BRAILLE (272-4553).