The Miracle of Sight — New Hope for the Blind
This is the final article in a five-part series of web features that
explores the wonderment of eyesight, the care and keeping of eyes, common eye
ailments and treatments, the future of eye care and the emerging hope for the
blind.
Most of us can only imagine what it would be like to completely lose our
vision, but for millions of people around the world, a slow fade into blindness
is a sad reality. The top three causes of blindness do not steal vision
overnight. Rather, vision loss is progressive, moving toward a debilitating
loss and eventually, for many, into blindness. If you are living in a developed
nation, you might be surprised to learn that the three diseases most likely to
cause blindness in people around the world are cataracts, glaucoma and
age-related macular degeneration (AMD) – all are typically treatable
conditions.
Cataracts
In fact, there are 15 million cataract surgeries performed around the world
each year. However, outside of the U.S., cataracts are the leading cause of
blindness, and cases are expected to rise with the aging of the global
population. Cataracts, a clouding of the lens of the eye, can be effectively
treated through a surgical procedure where the cataract is removed and an
intraocular lens is implanted. Some of the newest transplanted lenses are
multi-focal or accommodating, allowing the patient to see well close up and at
a distance. Much research is now underway to develop a next generation
intraocular lens that will improve the overall vision for people who undergo
cataract surgery.
Glaucoma
There are 62 million people around the world suspected of having glaucoma,
yet it’s estimated some 75 percent are
undiagnosed due to its insidious onset and slow progression, as well as limited
access to health care. Glaucoma, a build-up of fluid pressure within the eye,
is treated by reducing intraocular pressure using a progression of methods –
starting with topical drops and climaxing with surgical placement of a shunt –
because the response to drug therapy typically declines over time. A number of
companies are working at improving existing devices that lower intraocular
pressure, including shunts. If the safety, reliability and efficacy of shunts
are improved, this device might be used earlier in the disease to halt its
progression.
Age-related macular degeneration
Approximately 133 million people around the world have AMD and it is the
leading cause of vision loss in people over 60. One form of AMD is caused by
improper blood vessel growth in the macula, the small central part of the
retina. Treating AMD begins with diet and lifestyle changes. Historically, the
next step has been laser surgery. The latest treatment involves drugs that
block VEGF (vascular endothelial growth factor), the growth factor necessary to
create new blood vessels. Thus, blocking VEGF addresses a principal cause of
AMD. Now under development by a number of companies are anti-angiogenic and
anti-inflammatory compounds that stop the growth of new blood vessels. At least
one company is exploring the use of radiation therapy to treat AMD.
More on the horizon
There is great hope for people with retinal diseases, including retinitis
pigmentosa, agenetic eye disease that causes progressive loss of vision.
Progress is real, and includes early work on stem cell and retina transplants,
as well as electrical retinal transplants. The challenge for researchers is to
get a signal to the brain that it can process. Initially at least, patients who
undergo these treatments may see patterns of light and dark that comprise a
basic level of vision.
The bionic eye is also under development. Some patients have already
received bionic eye transplants, where electronic receivers are implanted in
the eye that take signals from a camera mounted in a pair of glasses. The
electrodes stimulate the remaining retinal nerves, creating a pathway for a
signal to be passed along the optic nerve to the brain. This technology may not
fully restore vision, but the hope is that it will allow the patient to see
light and dark patterns, enough to find doorways, follow someone else and help
with eating.
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