September 2023 Newsletter

MESSAGE FROM THE PRESIDENT

Dear Readers,

There’s still time to participate in our 4th Annual TGF Art Challenge to Celebrate Vision, raising money for vital research. Through September 15^th, we invite everyone who makes art, and everyone who appreciates art, to join us.

If you are an artist – amateur or professional -- you can share a digital copy of your artwork with us, your friends, family, colleagues, and other viewers, and ask them to honor your artistic vision by making a gift on TGF’s Art Challenge page.

Or, you can make a gift in honor of one of our artists!  We are delighted that eight glaucoma patients are already among the participating artists this year. Each artist is sharing a vision and asking you to bring it into focus with your gift. You’ll find more information elsewhere in this newsletter.

Every dollar we raise through the Art Challenge will support new glaucoma research in our first grant cycle of 2024. TGF understands the importance of partnerships to achieve our mission. We are most grateful to our Art Challenge Platinum Sponsor Endace and thank them immensely for their generous support.

In our next first webinar on September 18, Dr. Andrew Feola, PhD, of Emory University will talk about a subject he presented at our recent June Think Tank – the Role of Estrogen and Menopause in Glaucoma.  I hope you will join us.

We welcome your participation and support of all that we strive to accomplish.  

Elena Sturman

DOCTOR, I HAVE A QUESTION.
 

Why is my glaucoma getting worse even though my pressures are normal?

 Question answered by John Berdahl, MD
Vance Thompson Vision
Sioux Falls, SD

Dr. Berdahl is a board-certified ophthalmologist. He is widely regarded as one of the leading international cataract surgeons. He is one of the very few surgeons in the United States who is also fellowship trained in cornea, glaucoma, and refractive surgery.

Eye pressure is only one factor in glaucoma. In fact, historically, we’ve set the normal range of eye pressure not based on where patients get worse, but based on what’s been determined to be average eye pressures, from 11 to 21.

Outside the United States, especially in countries like China, Japan and other East Asian countries, more than 70 percent of glaucoma is what we call normal tension glaucoma – glaucoma that occurs even though the pressure is in the normal range. In the US it’s more like 30 percent of glaucoma cases have pressure in the normal range.

The key factor is what pressure do you need to stop progressing. And we can’t know that until we get it low enough and observe stability in your visual fields and the scans of your optic nerve.

There are many factors that have been implicated in glaucoma. The one I believe makes the most sense is intracranial pressure. Many patients with normal tension glaucoma have a low intracranial pressure (ICP), also known as cerebrospinal fluid pressure.

We’ve done research in this area as have many others and the optic nerve is exposed to two different pressures in its course from the eye to the brain ­- the eye pressure (IOP) and the brain pressure (ICP).  If the eye pressure is high or, if the intracranial pressure is low, a pressure gradient is created across the optic nerve head as it travels from the brain to the eye.

There is a significant amount of evidence that this pressure gradient is detrimental to the optic nerve and causative of glaucoma. Other possibilities are related to low blood pressure, low blood flow at the optic nerve head and other mechanisms such as inflammatory conditions.

The key to treatment would be to balance the IOP with the intracranial pressure. But since we can’t directly measure ICP we balance the pressures by progressively lowering the eye pressure, looking for stability of your glaucoma. If you’re not stable, then we escalate therapy to try to achieve a pressure that does confer stability. Normal tension glaucoma can be difficult to treat because it’s hard to lower an eye pressure that’s in the normal range.

Many researchers are working on new approaches and new therapies to lower eye pressures safely in patients with glaucoma. Hopefully those technologies can find their way to patients in the not-so-distant future.

While many people think that eye pressure is how glaucoma is diagnosed, normal tension glaucoma cannot be detected by checking IOP alone. Glaucoma is diagnosed by looking at the optic nerve, by doing OCT imaging, by looking at the retinal nerve fiber layer and by visual field changes. Many times we use measuring IOP as a screening approach to catch people who have glaucoma. But there is really no substitute for a thorough, comprehensive eye exam.

Other features of normal tension glaucoma are typical of other types of glaucoma, although we sometimes see people who have a higher incidence of migraines, or Raynaud’s phenomenon, and a higher incidence of low blood pressure, especially at night.

And while many countries are researching ways to measure intracranial pressure, for now the only reliable way to do that is via a spinal tap. No non-invasive way has proved to be useful to date. Hopefully we will be able to do that in the future. 

PREGANCY AND GLAUCOMA

Given that women are having children later in life, the chance that women with glaucoma are pregnant is greater than it was earlier. In fact, according to the U.S. Census Bureau, that trend has pushed the median age of U.S. women giving birth from 27 to 30, the highest on record.

So, it’s more important than ever for women with glaucoma to work closely with their ophthalmologist and OB/GYN when thinking about having a family. By discussing plans to become pregnant, a concerted effort can be made to achieve intraocular pressure (IOP) control on minimal or no medications, minimizing risk to the fetus while safeguarding the eye. Each case has to be evaluated on an individual basis.

Some patients are able to discontinue all glaucoma medications for the first 12 weeks. This might be possible, for example, if a patient is a glaucoma suspect or has early glaucoma with limited optic nerve damage and modestly elevated IOP. Frequent monitoring is the key. 

In other cases, discontinuing glaucoma medications is not possible, for example, if a patient has substantial optic nerve damage or extremely elevated IOP levels and is not able to tolerate uncontrolled IOP even for a short period of time. In such cases, the physician would try to prescribe the fewest possible medications, thoughtfully selected and dosed to minimize risks to the fetus. The advent of several newer glaucoma medications (e.g. Vyzulta™ and Rhopressa™) with good safety profiles is a positive factor for glaucoma patients who are considering pregnancy.    

Sometimes surgery may be the best option for patients who cannot achieve an acceptable IOP level with minimal or no glaucoma medications. If possible, surgical procedures to control IOP are best performed prior to conceiving so that the IOP level can be controlled and stable throughout the entire pregnancy.

If necessary (SLT) Selective laser trabeculoplasty can be performed during pregnancy. Incisional surgery, such as trabeculectomy, is safest prior to conception. There are now a variety of FDA-approved minimally invasive surgeries (MIGS) that offer significant advantages to the options pregnant patients faced earlier. MIGS typically are performed through a small incision in the eye with minimal tissue trauma, thereby offering a safer alternative as well as a faster recovery period.

There is no data suggesting problems with labor and delivery of a newborn. Periods of extreme straining during delivery may raise IOP, but this is very brief. Nursing must be considered as well, and warrants a discussion between the patient and her doctors as glaucoma medications may also be secreted into breast milk when nursing. Decisions on glaucoma treatments during the nursing period must be carefully considered.  

And finally, many mothers ask if their glaucoma puts their child at risk for developing the disease. Family history is a significant risk factor. Once a child is old enough to sit still for an eye examination, the child should get tested, and retested at periodic intervals.  Be sure to let your child's pediatrician know that you have glaucoma.