What is Glaucoma?
Glaucoma is a disease of the optic nerve - the
part of the eye that carries the images we see to the brain. When damage to the
optic nerve fibers occurs, blind spots develop ...
Glaucoma: A Closer Look
Glaucoma is the leading cause of
blindness in the United States. Since the disease may progress without pain or
early warning symptoms, an estimated three million Americans who have the
disease may not even know it. Early detection of glaucoma is now easier with
current technology.
Capital Eye Center uses the Heidelberg Retinal Tomographer (HRT), a highly
advanced diagnostic instrument that helps detect glaucoma early and monitor its
progression. This technology uses a scanning confocal laser to create a three
dimensional image of the optic nerve and surrounding tissue.
The laser, which is not powerful enough to harm the eye, first focuses on the
surface of the nerve and captures the image. Subsequently the laser can focus
through the top layer unlike a photographic image. It obtains images deeper and
deeper below the surface (similar to how a CT scan takes thin slice images of
our body). The stack of 32 images is then analyzed to create a very accurate
three dimensional image of the optic nerve. All of these images can be obtained
in just a few seconds.
The images are used to compute things such as optic cup volume, mean retina
nerve fiber layer thickness, and the area or volume of the optic nerve rim.
These parameters can be helpful in diagnosing or following glaucoma patients.
For example, the images can be compared to a normal population database to
highlight areas of the nerve that fall outside of the "normal range". This could
help in the diagnosis of glaucoma.
Changes in the optic nerve are a sign of glaucoma. As these optic nerve
structural changes often precede visual field changes, one may be better able to
diagnose glaucoma by closely following the optic nerve appearance. Serial HRT
testing, just like serial visual field testing, can show glaucoma progression.
Changes in rim or cup volume may indicate worsening of the disease.
American Academy of Ophthalmology: brochures and textual
content. www.aao.org
