EXAMPLES OF VISUAL FIELDS IN GLAUCOMA
VISUAL FIELD ANALYZER
Visual field testing or simply side vision
testing is done in medicine in numerous
conditions, such as neurology and brain
disorders but in ophthalmology this test is
used most in the diagnosis and
management of glaucoma. There are
numerous manufacturers out there
producing excellent pieces of equipment
but Humphrey Field Analyzer is probably
most used machine in the US.
This test can be done in several modes
such as screening but a threshold test is
more desirable since it does more in depth
analysis but also takes more time. Even a
threshold test does not pick up very early
damage from glaucoma.
The visual field test is used to assess any
damage to peripheral vision and if any
defect is found then rest is repeated
periodically to see if the progression of
glaucoma has been arrested. If a
subsequent test shows worsening of the
field defect, then more aggressive
treatment may be needed.
SERIAL PHOTOGRAPHS OF THE OPTIC NERVE HEAD ARE
VERY VALUABLE TOOL IN THE MANAGEMENT OF
VERY SMALL CHANGES IN THE CENTRAL CUP OR
CHANGES IN THE NERVE FIBER BUNDLES OR EVEN SMALL
HEMORRHAGES COULD EASILY BE MISSED BY NAKED
HUMAN EYE BY WHEN SERIAL PHOTOGRAPHS ARE
COMPARED, SUCH MINUTE CHANGES CAN BE PICKED UP
AND TREATMENT COULD BE ADJUSTED ACCORDINGLY
ultrasound machine called "Pachymeter". Thickness of the cornea can
effect the intra ocular pressure measurement and therefore it is
usually checked in the beginning and pressure readings are adjusted
Since the corneal thickness does not change through out life, unless
person had a refractive surgery like LASIK, test is done only once.
is used to look at health of the optic nerve. Optic nerve is a little over a
millimeter in thickness and conveys images from the retina to the brain.
Though very small in diameter, the optic nerve has over a million
fibers packed inside it.
These instruments, Optic Nerve Fiber Analyzers, use scanning laser
technology to look at the thickness and health of these nerve fibers.
These instruments are very precise and are extremely valuable in the
management of glaucoma. Tests may be repeated periodically to
assess status of the optic nerves and progression of the disease.
There are several different instruments of this kind available today.
Our office uses two of them, GDX and OCT, which are almost a
standard today in the management of glaucoma.
by measuring the thickness of the retinal nerve fiber layer.
GDX has a database containing bilateral retinal-verve fiber
hundreds of normal subjects. The database compares patients' scans
with normals matched for age, race and gender and generates a color
printout of the results.
such cases treatment can be started before patients have visual field
loss from glaucoma. Test is done when glaucoma is suspected and
periodically repeated to see if the progression has been stopped.
A look at GDX report
Left side shows
fiber layer loss,
right side is normal.
|EYE CENTER of MISSOURI