Understanding Glaucoma
Glaucoma is a general term for many conditions that cause progressive damage to the optic nerve resulting in loss of vision. Usually, the eye pressure is elevated, causing direct or indirect optic nerve damage. The pressure is high because the fluid, or aqueous, produced by the eye is blocked from getting to the drain, or trabecular meshwork, or the drain itself is clogged.
If the circulation to the optic nerve is poor, then even “normal” pressures may compromise blood flow, causing loss of vision. If a patient shows evidence of optic nerve injury on examination and/or shows an elevated intraocular pressure, then perimetry, or a visual field examination, is performed. Perimetry involves utilizing a computer program to measure hundreds of spots in your side (peripheral) vision within 4 minutes. If a visual field loss is detected, one of the following treatments will be recommended:
- Topical medications (drops)
- Laser surgery
- Systemic medications (tablets or capsules)
- Viscocanalostomy or trabeculectomy
Our goal is to halt progression of the disease with the least amount of medical or surgical intervention, allowing the patient to maintain useful vision throughout his or her lifetime.
Argon/YAG Laser Glaucoma Surgery
If drops fail to control your glaucoma or if you are considering potential alternatives to using drops, there are surgical options to reduce your intraocular pressure. Surgery can facilitate the outflow of fluid (aqueous) or reduce its production.
If you are at risk for severe and sudden visual loss due to a potential blockage of fluid enroute to the natural drainage ducts of your eye, Argon and YAG lasers can be used to create a “by-pass” opening to ensure that this blockage does not occur. This procedure is known as Laser Peripheral Iridotomy, or LPI.
If you are without risk of a sudden blockage, but have elevated pressures due to problems within the drainage ducts proper, you can be treated with the YAG laser. This procedure is known as Selective Laser Trabeculoplasty, or SLT. SLT can safely reduce your dependence on glaucoma drops and helps control the pressure long term by naturally enhancing the function of the outflow drains in your eyes.
For patients requiring a decreased production of fluid, endocyclophotocoagulation, or ECP, is an option. A tiny diode laser can directly treat the ciliary processes (fluid producing tissue), which reduces fluid production and lowers the pressure.
Minimally Invasive Glaucoma Surgery (MIGS)
Approximately 10% of patients who undergo cataract surgery have a diagnosis of mild to moderate glaucoma. In the past, there were no great options for simultaneous surgical treatment of cataracts and glaucoma, especially for those patients whose pressure was controlled with eye drops. However, that has changed recently thanks to the development of a new device that can be safely implanted in just a few minutes immediately following cataract surgery.
The Hydrus glaucoma device which is a small tube-like structure that was developed using the same type of stent technology used for opening clogged arteries in the heart and elsewhere. Rather than opening an artery however, we use this device to open the fluid drainage system of the eye creating a lasting intraocular pressure lowering effect. While cataract surgery alone has been shown to lower pressure in glaucoma patients, the Hydrus has an added advantage in a significant number of people. In fact, in the first global study of Hydrus patients, 65% remained off pressure lowering drops through 4 years and counting. Given its small size, ease of implantation, low risk and effectiveness, we recommend this procedure for all our patients who qualify.
For more information about the effectiveness of this device, please visit the following websites:
Selective Laser Trabeculoplasty
Selective Laser Trabeculoplasty, or SLT, is a form of laser surgery that is used to lower intraocular pressure in glaucoma. It is used when eye drop medications are not lowering the eye pressure enough or are causing significant side effects. It may sometimes be used as initial treatment in glaucoma.
SLT has been in use for 15 years in the United States and around the world. In this article we present some of the unique aspects of this treatment along with observations from years of experience and treatment of patients. The article is designed as a discussion to answer the most common patient questions and concerns regarding the procedure.
- Who is a candidate for SLT?
Patients who have open-angle glaucoma (the drainage system in the front part of the eye is open) and are in need of lowering of their intraocular pressure (IOP) are eligible for the procedure. Your eye doctor will make the final determination if you are a candidate. - How does it work?
Laser energy is applied to the drainage tissue in the eye. This starts a chemical and biological change in the tissue that results in better drainage of fluid through the drain and out of the eye. This eventually results in lowering of IOP. It may take 1-3 months for the results to appear. - Why is it called Selective?
The type of laser used has minimal heat energy absorption because it is only taken up by selected pigmented tissue in the eye. Sometimes it is referred to as a “cold laser.” Because of this, the procedure produces less scar tissue and has minimal pain. - What are the risks?
One key aspect of SLT is a favorable side effect profile, even when compared with glaucoma medications. Post-operative inflammation is common but generally mild, and treated with observation or eye drops or an oral non-steroidal anti-inflammatory drug. There is an approximately 5% incidence of IOP elevation after laser, which can be managed by glaucoma medications and usually goes away after 24 hours. - How effective is it?
SLT lowers the IOP by about 30% when used as initial therapy. This is comparable to the IOP lowering of the most powerful and commonly used class of glaucoma medication (prostaglandin analogs). This effect may be reduced if the patient is already on glaucoma medications. - How long does the effect last?
The effect will generally last between 1-5 years, and in rare cases, longer than that. If it does not last at least 6-12 months, it is usually not considered successful. - What happens if it wears off?
If SLT is effective at lowering IOP but this wears off over several years, the procedure can be repeated But the second treatment may not be as effective as the first and may not last as long. If SLT is not initially successful, repeat treatment is not likely to be effective. Alternatively, glaucoma medication can be used if the effect wears off over time. - What happens if it doesn’t work?
If SLT fails to lower the IOP, then the glaucoma is treated by other means such as medications or conventional surgery. The laser does not affect the success of these other types of treatment. - What is the cost?
Since the procedure is an accepted glaucoma treatment, and is FDA approved, it is covered by Medicare and medical insurance. The cost for an uninsured individual or with an insurance co-pay will vary. - Will I still need to use glaucoma medications?
Some patients can be controlled with just laser treatment. Others require additional IOP lowering and may therefore need to use glaucoma medication as well. Think of the SLT as equivalent to one glaucoma medication. Just as some patients will require more than one glaucoma medication to control their IOP, some may also require laser plus one or more glaucoma medications. It is important to remember that SLT is not a cure for glaucoma, just as medication and surgery are not. Whatever method is used to treat glaucoma, appropriate follow up and testing with your eye care professional is critical.
Laser Peripheral Iridotomy
Laser peripheral iridotomy is the standard first-line treatment in closed angle glaucoma and eyes at risk for this condition.
It has been used since 1984 both as treatment and prevention of the disease.
- What is the angle and what is closed angle glaucoma?
The angle is the space between the clear part of the eye (cornea) and the colored part (iris), close to their meeting point near the edge of the iris. It contains the trabecular meshwork ™, which is the main structure that directs fluid out of the eye.In closed angle glaucoma, the angle is closed in many or most areas, causing increased eye pressure, which leads to optic nerve damage, and possible vision loss. This rise in eye pressure may occur suddenly (an acute attack of angle closure) or gradually. There are also precursor forms of the disease in which the angle is closed but the eye pressure is not high and the optic nerve is not affected yet.
- How does laser iridotomy work?
It creates a hole in the outer edge of the iris, leading to an opening of the angle in the majority of cases. After the angle is widened from the procedure, the TM is exposed and fluid outflow is enhanced.
- Who is a candidate for laser iridotomy?
It is recommended in eyes which have the angle closed for at least half the eye. This is determined with a test called gonioscopy, which is done by the eye doctor in the office.
- What should I expect during the procedure?
The eye is usually pretreated about half an hour before the procedure with drops that make the pupil small. Just before the procedure, anesthetic drops are placed to numb the surface of the eye, a lens is then placed on the eye to perform the laser. The procedure usually takes 5-10 minutes and some patients may experience minor pain.
- What should I expect after the procedure?
There is temporary blurriness of vision. The eye may be a little red, light sensitive, and/or uncomfortable, and there may also be a mild headache due to the eyedrops given before the laser. The eye pressure is usually assessed within 30 minutes to 2 hours after the laser and anti-inflammatory eyedrops are usually prescribed for a few days.
- Will the laser improve my vision?
No. Iridotomy is intended to preserve the vision and prevent glaucoma from appearing or progressing.
- What are the risks?
Possible risks include, rise in eye pressure, bleeding at the laser site, and inflammation; these are usually temporary. Closure of the iridotomy may occur, requiring retreatment. Extra visual images including bright lights or flashes, or double vision in the treated eye, may rarely occur; this risk is reduced by positioning of the iridotomy in an area that is not covered by the eyelid.
- What happens if it doesn’t work?
In about 25% of cases, the angle may not open. Depending on the situation, some patients might need further laser procedures, medical treatment, or surgery. It may be possible that your ophthalmologist suggests close follow up.
- If I have glaucoma, will I still need to use my glaucoma medications?
Yes. Laser iridotomy is not a substitute for glaucoma eye drops in most cases if the patient is already on medication prior to the procedure.
- How long does the effect last?
Although the angle widens in most cases after laser, normal age-related changes may subsequently alter the angle region. Cataract formation could close the angle again and cataract extraction may be required.