Laser Surgery for Open Angle Glaucoma
Argon Laser Trabeculoplasty (ALT)
This is a laser procedure where 50micron laser spots are placed in the trabecular meshwork to open up the meshwork and allow more fluid to drain from the eye. This procedure is not used as much as a newer type of laser is available.
Selective Laser Trabeculoplasty (SLT)
This is a newer laser called a “cold” laser which uses a 532nm frequency-doubled Q-switched laser (SLT) that targets the pigment cells in the trabecular meshwork and makes very microscopic openings in the trabecular meshwork. This allows better drainage to lower the eye pressure. Laser treatment is an effective way to treat glaucoma without the side effects or costs of medications.
Cycloablation of the ciliary processes behind the iris with a diode laser lowers IOP by destroying the cells that produce the aqueous humor.
Laser Surgery for Acute Angle Closure Glaucoma
The treatment for angle closure glaucoma is surgical. A full thickness opening in the peripheral iris is made using a Nd:Yag laser to make the opening in the iris. The opening is like a safety valve that allows the fluid in the eye a more direct access to the trabecular meshwork.This allows the angle to open which in most cases prevents the angle from closing. It is used if the attack has already happened to open the angle. It is also used in cases where the angle appears so narrow that the angle may close as a preventive measure.
Glaucoma surgery is indicated when the other forms of glaucoma treatment are not adequately controlling the intraocular pressure.
This is the most common form of glaucoma surgery. The outer covering over the sclera (white portion of the eye) is called the conjunctiva. The conjunctiva is opened and a partial thickness flap in the sclera is made and dissected up to the cornea (clear portion of the eye). Under this flap an opening is made into the anterior chamber of the eye. An opening is made through the iris called an iridectomy. The flap is then closed as to allow the fluid to drain out of the eye in a controlled manner. The conjunctiva is closed and the fluid collects under the conjunctiva and forms bleb .The fluid is then adsorbed. Many doctors use Mitomycin-C before closing the conjunctival layers to diminish the scarring which could seal the opening closed.
There are several different brands of glaucoma shunts. The first was the Molteno . Other shunts are the Baerveldt shunt, Ahmed valve shunt, Express mini shunt and the pressure ridge Molteno. These are being used by doctors more often. They are indicated in cases where a traditional trabeculectomy may not work as an example neovascular glaucoma and may be used by some doctors as their primary surgical procedure for glaucoma. The surgery is similar to trabeculectomy with the drainage tube of the shunt being placed into the anterior chamber and the conjunctiva is closed over the plate.