I have just about all of the degenerative conditions of the
pre-elderly, including glaucoma.
Yesterday I underwent a laser treatment for glaucoma that some of you
may find interesting.
First a little background.
Glaucoma is a condition in which the internal pressure of the eye is too
high. Normally, the aqueous humor that
fills the spaces in front of and behind the iris drains from the eye through a
mesh-like structure called the trabecular network at the same rate it is
produced. With glaucoma, however, the
exchange of fluid is out of balance and the internal pressure rises which
damages the optic nerve if untreated.
My glaucoma is controlled by the use of two kinds of eye drops, but a
relatively new laser treatment has been developed that has the potential to
reduce or eliminate the need for drops.
The procedure is called Selective Laser Trabeculoplasty
(SLT). An earlier procedure used an
argon laser to blast holes in the trabecular network to allow the fluid to drain,
but the destruction it caused limited it to a single use. The new technique is called “selective”
because it only affects some cells in the network. This laser is tuned so that only cells containing granules of
melanin, the pigment that makes skin brown, absorb its energy. As I understand it, the laser heats the
granules and either kills the cells directly or injures them enough that they
initiate programmed cell death and self-destruct. With cell death, substances are released that activate aspects of
the immune system that remodel the trabecular network and increase the outflow
of aqueous humor. The procedure can be
repeated if necessary.
What is it like to undergo SLT? First drops are used to constrict the pupil in the eye to be
treated. The drops can cause a
headache, but that is generally the only pain associated with the
procedure. When the eye is ready, the
patient sits in a chair opposite a chin and forehead rest similar to the ones
used for a slit-lamp eye examination.
The doctor shines a low-power red targeting laser into the eye and aims
it at the edge of the cornea. When the
beam is in the right position, the doctor fires the laser, and the patient sees
a flash of green light. The doctor
moves the targeting beam to another location and fires again for a total of
about 100 short that cover the circumference of the cornea. I found the treatment to be completely
painless, and it took perhaps five minutes to make the 100 shots. I have to use anti-inflammatory eye drops
four times a day for four days and go back in two weeks to see if the treatment
was a success. If so, then the other
eye will be treated.
