Glaucoma is a common condition affecting nearly three percent of the general population. There are many different types of glaucoma, but they all have two common features: (1) damage to the optic nerve in the back of the eye and (2) loss of the visual field (often described as the "peripheral vision"). Glaucoma is NOT just a high pressure in the eyes. Central vision is usually spared until glaucoma is quite advanced. It has generally been accepted that once the optic nerve is damaged, this damage is irreversible. Treatment has always been aimed at trying to prevent further damage.
Elevation of the intraocular pressure (pressure inside the eye) is the most common risk factor for glaucoma. While treatments, both medical and surgical, have been traditionally geared towards lowering the intraocular pressure (see below for further details), current research is more centered on how to protect the optic nerve from further damage or even how we may be able reverse this damage in the future. Glaucoma can easily be detected during a complete eye exam by your ophthalmologist. Dr. Cohn, a glaucoma specialist, spent a year-long fellowship studying and treating glaucoma patients at University of California in San Francisco.
What are the symptoms?
The most common type of glaucomas, the "open angle" type, often have NO SYMPTOMS until central vision is lost in the most advanced stages of the disease. Patients most often walk around with glaucoma and don’t even know they have it! That is why routine eye exams from your ophthalmologist are so important. Most patients are unaware that the pressure in their eyes may be elevated. "Acute angle closure glaucoma," a much less common variety, usually presents with a red, painful eye with blurred vision, nausea, and headache. Angle closure is an ocular emergency that requires prompt treatment by an ophthalmologist.
How is glaucoma diagnosed?
Glaucoma is diagnosed during a routine ophthalmic exam. The optic nerve is observed for damage. The intraocular pressure is measured easily in the office. Patients usually undergo a visual field test if the doctor is suspicious of possible glaucoma. This 20 – 30 minute test involves having the patient push a button every time he/she sees a small light flash on different parts of a viewing screen. This produces a sensitive map of areas where vision may be fading without the patient’s knowledge. A screening pressure check is not sufficient to diagnose glaucoma. Patients with "normal tension" glaucoma may have optic nerve damage with normal eye pressure.
What are the possible treatments?
Treatment often begins with eyedrops designed to lower the intraocular pressure. It has long been felt that reducing the pressure in the eye helps to slow optic nerve damage. Ongoing research may reveal that some of these drops may have a "neuroprotective" effect on the optic nerve.
Argon laser trabeculoplasty (ALT), a brief in-office laser procedure, has been used for many years to help reduce intraocular pressure. Laser spots are placed in the trabecular meshwork, the "drain" of the eye. This procedure appears to work better in older patients (over 50) and in those with certain types of glaucoma (pigmentary glaucoma).
Selective Laser Trabeculoplasty (SLT) is a newer type of glaucoma laser procedure performed by Dr. Cohn. The results are similar to ALT but the SLT laser causes less trauma to the drainage channels to the eye. This laser may also be repeated if the beneficial effect starts to wane with time. SLT is performed in the office and takes less than 10 minutes. Patients are comfortable through the entire procedure.
In the United States, surgical intervention is usually reserved for patients who have failed laser treatment (or are not a candidate) and have worsening glaucoma despite several medications. There are two main types of glaucoma surgeries:
Filtering surgery, or trabeculectomy, is the most common type of glaucoma surgery. A small flap is made in the sclera or white of the eye, allowing fluid to drain out of the front of the eye and exit around the side. Anti-scarring medicine is often used during the surgery to help prevent the flap from healing back down. The surgery has a greater than 85% success rate.
Valve implantation involves placing a silicone tube in the front chamber of the eye, which drains fluid to a small reservoir on the side of the eye. This is not felt by the patient. The success rate is greater than 80%. This procedure is often reserved for patients in whom a trabeculectomy has failed.
Normal Optic Nerve
Optic Nerve with
Advanced Glaucoma Damage