We have long understood that sleep apnea can have a significant impact on the health of your eyes. Among these risks of sleep apnea, glaucoma is among the most serious, because it can cause serious vision loss and eventual blindness with few warning signs.
The link between sleep apnea and glaucoma had been presumed to be high blood pressure. But as our understanding of glaucoma has evolved, it seemed this link was not as strong as we thought. Now researchers have discovered a new link between the two conditions, one that points to a more damaging connection that may be even harder to anticipate and treat. This new research says that traditional glaucoma treatments will not help people with sleep apnea–only sleep apnea treatment can save their vision.
What Is Glaucoma?
Glaucoma is sometimes described as the “silent thief of sight” because it’s a condition that can dramatically damage your vision with few warning symptoms. Even worse, vision loss related to glaucoma tends to start in the center of the visual field, and it can affect color and detail vision first.
Glaucoma is caused by damage to the optic nerve. As the nerve is damaged, it loses the ability to pick up visual data from the eyes and transmit that data to the brain. In most cases, damage to the optic nerve is caused by elevated intraocular pressure (IOP)–the pressure of the fluid in your eyes, which presses on to the retina and the vital connections to the optic nerve.
People are regularly tested for elevated IOP–that’s the test where your eye gets hit by a puff of air. If elevated IOP levels are detected, medications can be used to bring down IOP levels and prevent damage to the optic nerve.
However, some people develop glaucoma without elevated IOP, what is known as normal-pressure glaucoma. This has been poorly understood, but new research suggests it may be related to sleep apnea in many cases.
The Link with Sleep Apnea
So how is sleep apnea linked to glaucoma? People with sleep apnea are at an elevated risk for glaucoma, but why? In the past, people linked high blood pressure with elevated IOP. More recently, studies have shown that this link is not very strong. So the fact that people with sleep apnea have a higher risk of high blood pressure (hypertension) can’t explain the link between the two conditions.
Researchers then began to blame the link on nighttime elevations of IOP related to apneic events. When people stop breathing, the air pressure in their torso can increase, which can then increase the fluid pressure throughout the body, including the IOP.
So that’s what researchers in Japan set out to measure: did sleep apnea cause IOP to surge overnight when breathing stopped?
Sleep Apnea, Breathing, and IOP
However, when researchers were able to continuously monitor IOP during sleep, they found that sleep apnea didn’t actually cause IOP to surge. That’s because people tended to stop inhaling with sleep apnea rather than exhaling. This means that IOP doesn’t account for the optic nerve damage. It also means that the medications normally used to prevent glaucoma couldn’t be used to stave off damage related to sleep apnea.
Instead, researchers concluded that optic nerve damage was likely related to hypoxia. A lack of oxygen is very damaging to all tissues, but nerves like the optic nerve may be particularly susceptible.
If this is the case, it turns out that the only way to save your vision from glaucoma related to sleep apnea would be to treat the sleep apnea. But what type of sleep apnea treatment would be best for this? The new method of continuously monitoring IOP during sleep would allow us to determine whether CPAP, by elevating air pressure throughout the body, might also elevate IOP and potentially increase–or not decrease–your risk of glaucoma. If that turns out to be the case, it would be a strong argument in favor of oral appliance therapy for sleep apnea.
If you are concerned about glaucoma or other dangers of sleep apnea and are looking for the right sleep apnea treatment in Omaha, please call (402) 493-4175 today for an appointment with sleep dentist Dr. Roger Roubal at the Advanced Dental Sleep Treatment Center.