Evelyn C just celebrated her 70th
birthday. She's in great health and has lived alone
since her husband passed away five years ago. Evelyn's
fiercely independent and determined not to be a burden
on her family, so when she started having trouble reading
and watching TV, she made an appointment with her optometrist
without saying a word to anyone. She figured all she
needed was a stronger eyeglass prescription. She was
shocked to learn that her reading difficulties are actually
caused by age-related macular degeneration (ARMD), a
debilitating condition that's responsible for the majority
of cases of severe vision loss in the elderly. Now she's
petrified she'll lose her driver's licence and end up
isolated and alone like so many seniors.
"ARMD is responsible for 50% of
the patients registered as legally blind," says Dr Alan
Cruess, president elect of the Canadian Ophthalmological
Society and head of the Department of Ophthalmology
and Visual Science at Dalhousie. And you'll probably
see more cases of ARMD in your practice in the near
future. "As the population ages, ARMD is becoming a
rapidly growing health problem," says Dr David Wong,
associate professor of Ophthalmology and director of
the Clinical Fellowship Programs at the University of
Toronto. With that in mind, here's a rundown of what
you need to know about ARMD, and how you can help your
patients cope with the disease.
WHAT
TO WATCH OUT FOR
In the dark Specialists aren't sure exactly what
causes ARMD: some say it's a decrease in blood flow
to the eye, others blame inflammation or oxidative stress.
"The causes are multifactorial," explains Dr Wong. "There
are a lot of feedback mechanisms that play into this
condition." At the most basic level, vision loss is
caused by deterioration of the macula, the central and
most vital area of the retina. Central vision is lost
but peripheral vision usually remains intact, so patients
shouldn't need a cane or guide dog. Bur since ARMD attacks
central, or "high-definition", vision, they may have
trouble reading, driving, watching TV or even recognizing
people.
A strong family history, age, inadequate
nutrition, hypertension and smoking are all risk factors.
"But the best thing you can do is counsel your patients
to quit smoking," suggests Dr Cruess.
Wet vs dry The first phase
of ARMD is called the atrophic, or dry form. If it's
caught early enough, the patient's visual acuity can
remain stable for several years. But roughly 10-20%
of patients will eventually progress to the more serious
exudative, or wet form, which accounts for the vast
majority of cases of severe vision loss. At this stage,
abnormal blood vessels begin growing in the eye. "It's
like a weed growing in a crack in the sidewalk," explains
Dr Wong. "These abnormal blood vessels leak blood or
serum into the retina." At this stage, vision loss can
progress quite rapidly.
DIY diagnosis Elderly patients
can think loss of eyesight is a normal part of aging,
so it's not uncommon for them not to notice that anything
is wrong until the disease has already progressed. That's
why it's so important for you to keep a vigilant eye
on your patients' eye health. "Since there are fewer
and fewer ophthalmologists, we're going to depend more
and more on GPs to assist with the diagnosis," says
Dr Wong.
So what should you be looking for?
"Any change in reading vision ability with either eye
is one of the best markers," says Dr Cruess. Also watch
for yellowish deposits in the retina, called drusens.
"These can often be seen with an ophthalmoscope —
but be sure to tell your patient to look at the light
so the pupil is dilated," says Dr Wong. If a patient
complains of blurred vision, that should also send up
a red flag. "When lines that should be straight, like
door frames, become distorted, that's a good sign of
fluid accumulation in the retina," explains Dr Wong.
You can also test this by having the patient look at
a piece of graph paper or a standard Amsler grid. If
you notice anything's amiss, refer your patient to an
ophthalmologist as soon as possible.
Slowing vision loss Treatment
options for the dry form of ARMD are limited. The standard
therapy is a regimen of high doses of antioxidants known
as the age-related eye disease study or AREDS formulation.
"Studies have shown AREDS will slow down progression
of ARMD by 25% over seven years for certain subcategories
of the dry form of the disease," says Dr Wong. "It's
the best known therapy for dry ARMD right now." Studies
are currently underway to revisit the formulation, taking
into account recent findings that supplements of lutein
and omega-3 fatty acids may also have positive effects
on ARMD progression.
For the wet form of ARMD, photodynamic
therapy is the standard treatment. A special dye —
developed by Vancouver-based microbiologist Dr Julia
Levy — is injected into a peripheral vein and then
excited with a laser beam. "Free radicals are formed
that basically irritate the abnormal blood vessels and
close them off," explains Dr Wong. Normal blood vessels,
which don't absorb as much dye, are unaffected. Unfortunately,
not all patients are eligible for this treatment. You
should tell your patients their case will have to be
assessed by a specialist.
Another wet ARMD treatment, pegaptanib,
was approved in Canada just a few months ago. The drug
is meant to slow or stop the growth of abnormal blood
vessels by blocking a protein called vascular endothelial
growth factor (VEGF). "It's an injection into the eye
that has to be administered every 6 weeks for at least
a year," says Dr Wong. He warns the injections could
lead to infection, bleeding or even cataracts, but says
this treatment — and other similar ones currently
being tested — are generally worth the risk. "There
are a lot of new therapies about to hit the market that
are likely to make a significant difference," he says
optimistically. "It's a very exciting time."
Keep an eye on mental health
Studies have shown that patients with ARMD rate their
quality of life lower than patients with serious chronic
ailments like COPD or even AIDS. "Ninety percent of
the information humans take in is through their eyes,"
Dr Wong explains. "We take that for granted." ARMD can
compromise your patients' independence, increase their
risk of falls and fractures, and wreak havoc on their
emotional wellbeing. "Depression is very common in patients
with any sort of new vision loss," says Dr Cruess. "It's
remarkable how many life years they are willing to trade
if they can only have their vision back." Let your patients
know there are loads of visual and digital aids that
can help them get the most out of the vision they still
have and remind them that a positive attitude is key.
But he adds, "Doctors need to remain vigilant. If you
see a problem, you need to refer your patient to a therapist."
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