|Statement of Paul A. Sieving, M.D., Ph.D., Director, National Eye Institute, National Institutes of Health, on World Glaucoma Day|
NEI-Supported Research Continues to Advance Understanding of Glaucoma and to Contribute to Development of Therapies
The National Eye Institute (NEI), one of the federal government's
National Institutes of Health (NIH), joins today with other groups
around the globe to observe World Glaucoma Day. NEI reaffirms its
commitment to support ongoing research to better understand glaucoma,
to identify risk factors that lead to the development of the disease,
and to prevent vision loss and blindness.
Glaucoma is a group of disorders that damages the optic nerve
and leads to loss of visual function. If left untreated, it leads
to blindness. An estimated 2.2 million Americans have glaucoma,
and an additional two million do not know they have it. All of
these cases can be attributed to a form of the disease known as
primary open-angle glaucoma (POAG), the most common form of glaucoma
and one of the nation's leading causes of vision loss. Approximately
120,000 Americans are blind from the disease. Worldwide, nearly
70 million people are affected by glaucoma.
Glaucoma usually begins in midlife and progresses slowly. If detected
early, disease progression often can be stopped or slowed with
eye drops or surgery. High pressure inside the eye, which may be
associated with glaucoma, does not by itself mean that a person
has glaucoma. With its painless and gradual loss of vision, glaucoma
may have no early warning signs, but it can be detected during
a comprehensive dilated eye examination. An eye care professional
can see inside the eye to detect signs of glaucoma, such as subtle
changes to the optic nerve, before any symptoms appear. Once vision
is lost, it is gone forever.
NEI's support of glaucoma research continues to generate
breakthroughs in understanding the disease. These advances in scientific
knowledge encourage the development of new diagnostic tests and
therapies to prevent and treat glaucoma. For example, NEI supported
the basic research that led to the development of the drug latanoprost
to treat glaucoma.
NEI currently supports 244 glaucoma studies at
a cost of approximately $60 million. Over 15 years, investigators
conducting a number of NEI-supported studies have reported significant
findings. For example, in the Early Manifest Glaucoma Trial, scientists
found that the progression of glaucoma was less frequent in patients
who were treated early than in those who were treated later or
who received no treatment. In the treated group, eye pressure was
lowered by an average of 25 percent. This finding has led to the
emerging consensus in the medical community that lowering pressure
inside the eye can, in many cases, slow glaucoma damage and vision
In another trial, the Ocular Hypertension Treatment Study (OHTS),
investigators discovered that eye drops used to treat high pressure
inside the eye are effective in delaying the onset of glaucoma
in people at higher risk for the disease. The pressure-lowering
eye drops reduced by more than 50 percent the development of POAG.
Those at higher risk for developing glaucoma are:
- African Americans over age 40
- Everyone over age 60, especially Mexican Americans
- People with a family history of the disease.
In addition, OHTS investigators identified other risk factors,
such as certain anatomical features of the optic nerve and the
thinness of the cornea. These discoveries have been useful in helping
eye care professionals predict who will likely develop glaucoma
and who will benefit from therapy.
Another area of progress in developing therapies for treating
glaucoma and other diseases in which nerve cells are damaged is
called neuroprotection. Among the approaches being studied are
stem cell therapy, gene transfer therapy, and the use of proteins
called neurotrophic factors. The major feature of glaucoma is the
death of retinal ganglion cells (RGCs), the nerve cells that make
up the optic nerve. NEI-supported investigators recently used gene
transfer therapy in rodent models of glaucoma to provide an ongoing
supply of an essential neurotrophic factor to the optic nerve and
were able to show significant improvement in the survival of RGCs.
NEI-supported scientists have made considerable progress in understanding
the genetic and cellular bases of glaucoma, whether accompanied
by high pressure inside the eye or not. For example, mutations
in a gene called myocilin have been linked to a rare,
inherited form of glaucoma in which the fluid filtering part of
the eye, called the trabecular meshwork, is involved. This genetic
mutation may be another contributing factor in causing high pressure
inside the eye.
Though vision loss from glaucoma is often associated with pressure
that damages the optic nerve, some glaucoma patients do not have
high pressure. These people are said to have normal-tension or
low-tension glaucoma. NEI-supported scientists have made considerable
progress in understanding the genetic and cellular bases for this
type of glaucoma as well as for the other forms of glaucoma. For
normal-tension glaucoma, investigators have identified a gene known
as OPTN. Four different mutations in this gene have been
found in families with normal-tension glaucoma. In addition, this
gene produces a protein called optineurin that is found in both
retina and brain tissue and that interacts with other proteins
associated with optic nerve damage. Research into OPTN reinforces
the importance of protecting the optic nerve's RGCs.
NEI applauds the establishment of World Glaucoma Day and looks
forward to contributing in the years ahead to the advancement of
public awareness of glaucoma through its National Eye Health Education
Program (NEHEP), increased public acceptance of the need for regular
comprehensive dilated eye exams, and the importance of continuing
scientific research and development of effective therapies.
The National Eye Institute (NEI) is part of the National
Institutes of Health (NIH) and is the federal
government's lead agency for vision research that leads to
sight-saving treatments and plays a key role in reducing visual
impairment and blindness. For more information, visit the NEI
Website at http://www.nei.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.