Is There a Surgery for Angle-Closure Glaucoma?
A laser iridotomy is the most commonly performed procedure. During a laser iridotomy, the ophthalmologist uses a laser beam to make a hole in the iris to re-establish normal drainage and reduce the pressure inside the eye. By making a hole in the iris, the fluid (aqueous humor) is better able to drain out from the posterior chamber to the anterior chamber of the eye.
Prior to a laser iridotomy, the ophthalmologist prescribes medicines to reduce the pressure inside the eye and to clear up the cloudiness of the cornea that occurs during an acute attack of angle-closure glaucoma. Also, because the pupil is often partially dilated (or enlarged), it is constricted (or made smaller) before laser surgery.
Laser iridotomy is the treatment of choice for angle-closure glaucoma. Iridotomy is performed using either an argon laser or an Nd:YAG laser.
The laser beam creates an opening in the iris through which the fluid (aqueous humor), which is trapped in the posterior chamber, can reach the anterior chamber and the trabecular meshwork (or drainage channels).
As the fluid flows into the anterior chamber through this opening in the iris, the pressure behind the iris (inside the eye) falls, allowing the iris to return to its normal position.
This procedure usually opens the angle of the anterior chamber and relieves the blockage at the trabecular meshwork. In patients with plateau iris, iridotomy will usually break an attack of angle closure. However, the structural abnormality of the peripheral iris will still exist and must be monitored.
If the cornea is extremely cloudy or if the person cannot cooperate, or if the iris cannot be accessed with a laser beam for some reason, a surgical (or incisional) iridectomy is performed, in which the eye doctor creates the hole in the iris through a surgical incision.
Laser gonioplasty is sometimes used together with iridotomy as a treatment for angle-closure glaucoma or as a temporary measure to open the angle until a laser iridotomy can be performed.
During a laser gonioplasty, a laser beam is used to create multiple burns in the iris. These burns cause the iris to contract, pulling the iris out of the angle and opening the angle, causing the pressure to decrease.
Other aqueous drainage surgery
In situations in which the attack of acute angle-closure glaucoma has existed without treatment for a longer period of time or there have been repeated attacks of acute angle-closure glaucoma, adhesions and scarring may be present between the peripheral cornea and the iris (peripheral anterior synechiae or PAS), permanently closing the angle. This is called chronic angle-closure glaucoma.
This type of glaucoma is not curable with iridotomy or iridectomy. In such cases, the ophthalmologist will surgically create a new drainage system for the fluid in the anterior chamber, either through a trabeculectomy or using an aqueous shunt device.
In patients with plateau iris, lens extraction may be necessary to provide more room for the peripheral iris to move posteriorly.