Glaucoma is one of the leading causes of blindness and visual impairment in the United States. It is a disease that involves irreversible damage to the optic nerve usually caused by increased eye pressure. It often has no symptoms and slowly reduces peripheral vision and can eventually diminish the central vision. A simple, painless eye exam can detect the disease. With early detection and treatment, glaucoma can usually be controlled and blindness prevented.
There are two main types of glaucoma. The most common is open angle glaucoma. With this condition, the fluid in the eye is not draining properly through the trabecular meshwork. There are generally no symptoms in the early stages of this type of glaucoma.
The second type is closed angle glaucoma. This is a sudden build-up of pressure and poor drainage caused when the angles in between the cornea and the iris are too narrow. This can cause severe eye pain, redness of the eyes, blurred vision or halos around lights. Angle closure requires immediate medical attention to avoid permanent damage to the eye.
Glaucoma often has no symptoms; however, there are certain factors that increase the risk of glaucoma. These include:
• A family history of glaucoma
• Age of 45 or older without regular eye exams
• Abnormally high eye pressure
• African descent
• Previous eye injury
• Regular/long term use of Prednisone or other corticosteroid products
Patients with glaucoma should be seen regularly by an ophthalmologist to monitor their condition. Glaucoma can often be treated with medical therapy. There are several classes of eye drops that lower intraocular pressure. In cases where medical therapy is not sufficient, other procedures may be used to lower the intraocular pressure.
Selective Laser Trabeculoplasty (SLT): a laser procedure that lowers intraocular pressure (IOP) by increasing drainage. This is an office based, minimally invasive procedure with little to no side effects, scarring or pain.
Yag Laser Iridotomy: a treatment for narrow or closed angle glaucoma which uses a laser to make a small hole in the iris to increase the angle between the cornea and iris and encourage fluid drainage.
Trabeculectomy Surgery: this uses a laser to cut a hole in the sclera, creating a new passage and a collection pouch for fluid.
Minimally invasive glaucoma surgery (MIGS): MIGS procedures work by using microscopic-sized equipment and tiny incisions. While they reduce the incidence of complications, some degree of effectiveness is also traded for the increased safety.
The MIGS group of operations are divided into several categories:
• Miniaturized versions of trabeculectomy
• Trabecular bypass operations
• Totally internal or suprachoroidal shunts
• Milder, gentler versions of laser photocoagulation
Using tiny, microscopic-sized tubes that can be inserted into the eye and drain fluid from inside the eye to underneath the outer membrane of the eye (conjunctiva), two new devices seem to make the trabeculectomy operation safer. These devices (the Xen Gel Stent and InnFocus Microshunt) have shown excellent pressure lowering with improved safety over trabeculectomy in studies done outside the United States. If US study results are as good as those from overseas, FDA approval could follow within a year or two.
Most of the restriction to fluid drainage from the eye rests in the trabecular meshwork. Several operations have been devised using tiny equipment and devices to cut through the trabecular meshwork without damaging any other tissues in the ocular drainage pathway. Using a special contact lens on the eye, a tiny device is inserted into the eye through a tiny incision into the trabecular meshwork under high power microscopic control. The trabecular meshwork can either be destroyed (Trabectome or Trab360) or bypassed using a tiny snorkel-like device (the iStent). These procedures are FDA-approved but generally don’t get the eye pressure very low so are most useful in early to moderate stages of glaucoma.
Using tiny tubes with very small internal openings, the front of the eye is connected to the suprachoroidal space between the retina and the wall of the eye (Cypass or Glaukos shunts) to augment the drainage of fluid from the eye. This operation has relatively few serious complications and lowers pressures enough to be useful even in moderately severe glaucoma.
New Laser Procedures
Previously, laser cyclophotocoagulation was reserved for advanced glaucoma that could not be controlled despite trabeculectomy or tube shunts. The procedures were designed to reduce the fluid-forming capacity of the eye by targeting the delicate tissue (ciliary body) that makes the fluid. They sometimes produced severe inflammation that could reduce vision. Two recent additions to the laser treatment procedures have proven useful even before the glaucoma is far advanced. These are endocyclophotocoagulation and micropulse cyclophotocoagulation.