100 Laser Shots to the Eye

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.

I was attracted to SLT because it has the potential to make structural changes to the trabecular network that provide at least a temporary “cure” for the disease.