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Macular Degeneration: A blindness that confounds the scholars and compromises the afflicted
by Cheryl M. Craft
Retirement is contemplated as a
respite from scheduled labor and an interlude of reflection on life's
accomplishments. Happily that is true for many, but there is a darker
side that impairs and compromises the fulfillment of these
expectations. Cardiovascular events and cancer may strike to cut short
a life, but polls show that most individuals fear blindness and visual
impairment more than death. Among the most mature of our citizenry lies
the almost certain possibility of diminished vision.
Vision scientists
have made unprecedented advances in understanding how the eye works and
in devising methods to preserve vision. Many elderly develop cataracts
that obscure a clear vision, but modern surgical techniques allow the
removal of the cataractous lens and insertion of an artificial lens in
about 20 minutes, normally without complications or pain. A more
serious ocular condition is found in individuals with Type I or Type 2
diabetes, wherein the faulty metabolism of sugar leads to leaky blood
vessels that bleed within the light-sensitive retina and cause visual
loss. The bleeding within the eye must be controlled and this is now
achieved using laser cauterization.
The bane of the elderly comes
silently without pain to diminish the most sensitive vision upon which
we rely for sharp and colorful images. The condition is macular
degeneration, called age-related macular degeneration when it occurs in
later life. Unlike cataracts or diabetes, the cause of macular
degeneration remains a mystery—perhaps the last clinical mountain
remaining to be climbed in ophthalmology. There are many observations
that correlate with the final stages of the disorder, but little
evidence about what causes the death of cone photoreceptors within the
macular, a retinal specialization serving our central visual field. In
some cases, new blood vessels form and then bleed into the eye, causing
cone loss if left untreated by laser therapy. However, laser therapy
makes a burn, killing cells, and this is unacceptable within the macula
because the treatment would then cause blindness. A host of
possibilities for cause and treatment are being entertained and it
remains unclear which will be the first to prove successful.
The race is on for a cure!
Short-term, we expect that the surgeons and laser therapist will solve
the technical problems to provide an expedient treatment of macular
degeneration. We must push beyond the laser to the fundamental cause if
we are to provide lasting results. The seemingly magic mechanisms that
control vision and photoreceptor viability are being exposed and this
work must move forward for success. We look to the molecular and
cellular biologists to find the faulty, possibly genetic, mechanisms
that underlie macular degeneration. One of the first genetic clues is
now known and we are working to answer the questions of how and why!
Then we will have the knowledge to design therapeutics with smart-drugs
and possibly genetic therapy to correct the biological error.
At the beginning
of the twenty-first century, it is rewarding to look back on the last
century of vision research and clinical ophthalmology, admiring the
unexpected and unsurpassed achievements of many scientists. It is
equally comforting to look into the new century as it rises before us in
a new millennium. The summons to vision research and clinical
ophthalmology has been delivered already and a cadre of creative
scientists in the Mary D. Allen Laboratories for Vision Research is
looking forward to the challenge with expectation. A future in which
macular degeneration is controlled and eradicated awaits us and it will
provide to the elderly a release from the fear of blindness and the
mental disorientation that accompanies visual impairment.
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