Deciphering the Link Between Glaucoma and Sleep Apnea

Aug 03, 2016, by Dr. Becky Coats
Sleep apnea impacts every aspect of your health. There is virtually no system in your body that is not affected by the intermittent loss of breath.

But one of the dangerous links that is often overlooked is the impact that sleep apnea can have on your vision. Sleep apnea can significantly increase your risk of glaucoma, a condition that can lead to blindness if not properly treated.

For a long time, the link between the two conditions has been unclear, but now researchers think they have discovered why sleep apnea causes glaucoma. And the link means that oral appliances might be better than CPAP to save your vision.

sleep apnea can cause glaucoma

What Is Glaucoma?

Glaucoma is a serious threat to your vision. As glaucoma progresses, you will experience vision loss from the outer edges of your visual field. The vision loss can often go unnoticed until it has seriously limited your peripheral vision. That’s because there are few other symptoms of glaucoma, and the vision loss can be subtle at first but progress quickly.

Glaucoma is caused by damage to your optic nerve and to the delicate layer of cells that connects the retina to optic nerve. As these are damaged, visual data is no longer reaching the brain.

One of the most common forms of glaucoma occurs when elevated pressure in your eyes (intraocular pressure, IOP) causes damage to the optic nerve. This can be caused by conditions that block the drainage from your eye, causing fluid to build up inside your eye.

You get tested for this type of glaucoma if you see your eye doctor regularly–that’s the test where they hit your eye with a puff of air. When doctors detect an elevated eye pressure, they can prescribe medications that will lower the pressure.

But some people develop glaucoma without elevated IOP. This has been harder to detect and prevent. And now it seems that this is the type of glaucoma that’s linked to sleep apnea.

The Link with Sleep Apnea

There have been many explanations in the past for why sleep apnea causes increased glaucoma risk. We used to think that glaucoma was strongly related to elevated blood pressure (hypertension), which is also associated with sleep apnea.

But more research has cast doubt on this link, so hypertension can’t be used to explain the strong link between sleep apnea and glaucoma.

Another possible explanation is that when you stop breathing, the air trapped in your torso can increase the fluid pressure throughout the body, including your eyes. That’s what researchers in Japan set out to test with constant overnight monitoring of IOP, but they were surprised at what they found.

Sleep Apnea, Breathing, and IOP

When researchers monitored the eye pressure of people with sleep apnea, they found that the IOP didn’t surge when breathing stopped. That’s because breathing tended to stop when a person was inhaling, not exhaling. This caused researchers to conclude that IOP is not related to glaucoma risk in sleep apnea. This means that normal glaucoma medication likely won’t be helpful in treating glaucoma linked with sleep apnea.

So what is the link? Researchers concluded that it was likely caused by the intermittent oxygen shortages that occur in relation to apnea. So the best way to prevent glaucoma associated with sleep apnea is just to treat the sleep apnea.

But this study also raises the question: what is the best sleep apnea treatment to preserve vision. If thoracic pressure can elevate IOP, then wouldn’t CPAP–which forces pressure into the throat and lungs to keep them from collapsing–potentially elevate IOP as well. This would make oral appliances the best approach for preventing glaucoma. Now that we know how to monitor IOP continuously through the night, studies can be designed to test this hypothesis.

Until then, we know that the best sleep apnea treatment is the one that you will actually stick with. If you are looking for a more comfortable and convenient alternative to CPAP in the Dallas area, please call (817) 481-6888 today for an appointment with sleep dentist Dr. Becky Coats at Grapevine Dental.