Microinvasive glaucoma surgery offers reduced risks
February 21, 2019
Microinvasive glaucoma surgery (MIGS) refers to a new category of glaucoma surgery intended to reduce the risks involved with traditional glaucoma surgeries. MIGS typically is performed by using microscopic-sized equipment or implants, precision lasers, and tiny incisions in the eye, all of which leads to less tissue trauma and a more rapid visual recovery than traditional glaucoma surgery.
Some MIGS procedures can be performed as standalone operations, while others are usually done along with cataract surgery in patients who have visually significant cataracts and mild to moderate glaucoma.
MIGS is a new, exciting option in treating glaucoma. But it does involve some challenges, as new procedures are constantly being developed, and there is limited data about long-term outcomes after surgery. It’s important that patients find a surgeon who can help them navigate their options and weigh the benefits and risks.
What is glaucoma?
Glaucoma is progressive damage to the optic nerve, which transmits images from the eye to the brain. Glaucoma affects more than 3 million people in the United States and is normally associated with high pressure inside the eye (intraocular pressure) but not always. It often manifests as loss of peripheral vision, but it can progress to central vision loss and lead to blindness.
In the early stages, most patients have few or no symptoms. It’s similar to high blood pressure in that sense. As a result, it’s important to have regular eye exams. The American Academy of Ophthalmology recommends having an eye examination:
- Every five to 10 years for people
under age 40
- Every two to four years for people
ages 40 to 54
- Every one to three years for
people ages 55 to 64
- Every one to two years for people age 65 and older or who have glaucoma risk factors such as extreme nearsightedness, African or Hispanic ancestry, a family history of glaucoma, or a thin cornea.
Symptoms of glaucoma can include:
- Cloudy appearance in the front of
- Halos around lights
- Nausea or vomiting
- Redness or swelling of the eye
- Reduced or cloudy vision
- Sensitivity to light
- Slow loss of peripheral (side)
- Sudden, severe pain in one eye
If you wait to see a doctor until experiencing any of these symptoms, glaucoma usually is at a late stage. Diagnosing and treating glaucoma early is the best strategy to prevent eventual vision loss.
How is glaucoma diagnosed?
The most common factor associated with glaucoma is high pressure in the eye, but that’s only one risk factor. You can have high pressure in the eye and never develop glaucoma. You can have “normal” eye pressure and have glaucoma.
During a comprehensive eye exam, your doctor might use these common tests to assess for glaucoma:
- Checking your eye pressure
- A dilated-eye exam to view the
optic nerve and see if nerve fibers are thinning
- Formal peripheral vision testing
called visual field testing
- Optical coherence tomography (OCT) to examine the nerve fibers that feed the optic nerve to look for signs of glaucoma. OCT often helps us diagnose glaucoma earlier than using peripheral vision testing and a clinical examination alone.
Even after testing, we don’t always have a clear diagnosis. There are many patients in the middle ground whom we watch over time to see if their condition progresses into glaucoma.
How is glaucoma treated?
When treating glaucoma, the goal is to reduce eye pressure to prevent further damage to the optic nerve. A patient’s disease stage and lifestyle influence what treatment we recommend, which can include:
- Eye drops, which work to increase the outflow of fluid from the eye.
- Laser treatment, which we use to treat the eye's trabecular meshwork, or drainage system. The procedure increases the flow of fluid from the eye. This can be done in the clinic and typically is not painful.
- Traditional surgery, such as trabeculectomy or tube shunt. With a trabeculectomy, we use the eye’s own tissue to create a new drainage pathway in the eye for fluid to bypass the natural drainage system in the eye, which is not draining enough. With a tube shunt, we implant a flexible drainage tube into the eye to divert fluid inside the eye to an external reservoir. These surgeries have a higher risk profile and are reserved for patients who need that enhanced level of pressure lowering. The patients who need these surgeries typically have a relatively high risk of losing vision because of glaucoma.
- MIGS, which offers less-invasive surgical options to lower pressure inside the eyes. MIGS generally has a more favorable risk profile and might allow surgeons to both reduce pressure and lessen the burden of eye drop use that some patients must rely on.
With traditional glaucoma surgeries, there is a reasonable risk of complications, including:
- Bleeding inside the eye
- Cataract formation
- Decreased vision
- Double vision
- Infection in the eye
- Swelling of the cornea or retina
- Pressure that is too low
Most MIGS procedures have a good safety profile and a more rapid visual recovery, but there is a risk of bleeding in the eye or a short-term increase in eye pressure after the procedure. The specific risks and their likelihood can vary depending on the procedure. At UT Southwestern, my three colleagues and I use the following MIGS procedures, among others:
- iStent: Implanted in the eye’s drainage system, the iStent is about the size of a third of a grain of rice. It creates a permanent opening that improves the eye's natural outflow and lowers and controls pressure within the eye.
- Kahook Dual Blade: A single-use, microengineered blade makes parallel incisions to remove a strip of the eye’s drainage system to improve fluid outflow.
- Ab-Interno Canaloplasty: With this procedure, performed through self-sealing clear corneal incisions, we insert a microcatheter to open the eye’s natural drainage system.
- Endocyclophotocoagulation: Applying laser from inside the eye to the parts of the eye that create fluid, so that less fluid is produced in the eye.
MIGS procedures are still very new, so we’ll continue to learn more about long-term risks and effectiveness as we follow patients five or 10 years after a procedure. Moreover, new procedures and devices are being developed all the time. It can be difficult to navigate and know what to do, and we are happy to help you explore all options. We offer coverage in all aspects of eye care, so if a patient needs help with other ocular conditions, we can easily connect them with the appropriate specialist.