Primary Open-Angle Glaucoma (cont.)
IN THIS ARTICLE
Surgery is necessary when optic nerve damage due to glaucoma worsens (or is expected to worsen) at any given level of intraocular pressure and the pressure is not being lowered with 1-2 medicines.
Optic nerve damage may progress in some people because complying with the medical treatment becomes too difficult for them for the following reasons:
The most common surgical procedures for primary open-angle glaucoma are trabeculoplasty, trabeculectomy, drainage implant surgery, and ciliary body ablation. Each is briefly described below. If you need surgery, your ophthalmologist will discuss the appropriate surgical procedure with you.
A trabeculoplasty is usually done if medicine alone has not lowered the intraocular pressure. It may be done sooner if a person has certain eye diseases or if the person is black, because laser therapy may be most effective in these individuals.
During a trabeculoplasty, the ophthalmologist uses an argon laser beam (called argon laser trabeculoplasty, or ALT) or a selective YAG laser beam (called selective laser trabeculoplasty, or SLT) to place small spots (burns) on the trabecular meshwork, which further open the holes in the trabecular meshwork, allowing the fluid (aqueous humor) to flow better out of the eye.
A special contact lens (called a goniolens) is placed on your eye so your ophthalmologist can view the trabecular meshwork. You will sit at a slit lamp while the ophthalmologist performs the procedure.
A full treatment consists of 100 spots placed over the entire trabecular meshwork. This may be divided between 2 sessions consisting of 50 spots over each half of the trabecular meshwork. The entire procedure usually takes 30 minutes or less and is painless.
Intraocular pressure is usually reduced by 7-10 mm Hg, and it may last up to 3-5 years following a trabeculoplasty. Unfortunately, this decrease in intraocular pressure is not usually permanent. For those people who experience a rise in intraocular pressure or if the laser treatment is ineffective from the start, another surgical procedure is then necessary.
As with any surgical procedure, complications may occur but are rare. Your ophthalmologist will discuss the risks and benefits of this procedure with you.
Following the trabeculoplasty, your eye doctor will prescribe medicine to prevent inflammation. You will also continue with your glaucoma medicine. You will have several follow-up visits with your eye doctor to monitor your eye pressure.
Conventional incisional surgery
If medicine and laser therapy have failed to adequately control intraocular pressure, then conventional incisional surgery (also known as filtering surgery) may be performed. The most common filtering surgery is a trabeculectomy.
During a trabeculectomy, the ophthalmologist creates an alternate pathway (or drainage channel) in the eye to increase the passage of fluid (aqueous humor) from the eye. By constructing a new drainage channel, the aqueous humor is able to flow better from the anterior chamber into a bleb (a space created for drainage of aqueous humor) below the conjunctiva. As a result, intraocular pressure is lowered.
As with any surgical procedure, complications may occur but are not common. Your ophthalmologist will discuss the risks and benefits of this procedure with you. After this type of surgery, you are usually restricted from doing any heavy lifting or straining for several weeks, because you can create complications in the eye with excessive activity too soon after surgery.
Drainage implant surgery
Drainage implant surgery is generally performed after multiple attempts at a trabeculectomy have failed.
In drainage implant surgery, the ophthalmologist places a tube in the anterior chamber to shunt the aqueous humor. Different types of implants can be used, but most function by allowing drainage of the aqueous humor from the anterior chamber, thereby lowering intraocular pressure.
As with any surgical procedure, complications may occur. Your ophthalmologist will discuss the risks and benefits of this procedure with you.
Ciliary body ablation
Ciliary body ablation (also called cyclodestructive surgery) is a last resort and is reserved for those people with pressures that have not been lowered by medicine and other surgeries.
In this procedure, the ophthalmologist uses a laser (diode laser) to destroy a portion of the ciliary body, thereby limiting the production of aqueous humor. Intraocular pressure is then lowered because of less fluid being able to build up in the eye.
Cryotherapy (freezing the ciliary body) has largely been replaced by ciliary body ablation because the laser is better tolerated, is more effective, and is associated with fewer complications. Nevertheless, ciliary body ablation can permanently decrease vision, or it can cause the eye to shrink up and die (a condition called phthisis).
As with any surgical procedure, complications may occur but are uncommon; however, complications are more common with ciliary body ablation than with other surgical options. Pain and inflammation following the procedure are the most common complaints. Your ophthalmologist will discuss the risks and benefits of this procedure with you.
Jerald A Bell, MD
Richard W Allinson, MD
Francisco Talavera, PharmD, PhD
Robert H Graham, MD
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