Obstructive Sleep Apnea and Glaucoma

Obstructive sleep apnea (OSA) is a condition that causes repeated episodes of partial or complete obstruction of the respiratory passages during sleep.¹ Airway obstruction during sleep results in hypoxia, leading to arousal of the brain, sympathetic activation, and oxygen desaturation in the blood.¹ Repeated episodes of airway obstruction may subsequently cause fragmented, nonrestorative sleep.¹

The effects of OSA are wide-ranging, and the condition has been identified as a risk factor for cardiovascular, metabolic, and psychiatric disorders, including hypertension, stroke, diabetes, and depression.¹ Individuals with OSA often do not experience symptoms; however, those who do experience symptoms may report snoring during sleep, nocturia, night sweats, insomnia, daytime sleepiness and fatigue, memory and concentration issues, low energy and motivation, feeling unrefreshed despite getting the recommended 7 to 9 hours of sleep, and morning headaches.^1,2

See OSA Stats for details on incidence and awareness of this condition. Unmodifiable risk factors for OSA include male sex, older age, family history of OSA, craniofacial anatomy resulting in narrow airways, and race (eg, studies suggest that Black, American Indian, Hispanic, and Asian individuals are at higher risk).² Modifiable risk factors for OSA include obesity, medications that cause muscle relaxation and narrowing of airways, endocrine disorders, smoking, and nasal congestion or obstruction.²

DIAGNOSING OSA

A sleep study using polysomnography (PSG) can confirm the diagnosis and severity of OSA. This can be ordered by the optometrist, typically in conjunction with referral to a sleep specialist. When determining whether to order a sleep study, ask your patients: 1) Do you snore? 2) Do you wake up with a headache? 3) Do you often experience daytime sleepiness or fatigue? If a patient answers yes to these three questions, they need a sleep study. PSG is considered the gold standard of evaluation for OSA and involves a monitored, 8-hour sleep study conducted in a laboratory with an established scoring criteria for OSA-related respiratory events.² PSG can determine the need for supplemental oxygen, detect elevated carbon dioxide due to shallow breathing, monitor body position, and detect respiratory events, such as apnea (complete lack of airflow) and hypopnea (reduced airflow).² With this information, physicians can use established diagnostic criteria and grading scales to determine the presence and severity of OSA.²

OSA AND GLAUCOMA

The effects of OSA should be a concern of eye care professionals. OSA is associated with various ocular conditions, including nonarteritic ischemic optic neuropathy, papilledema, retinal vein occlusion, central serous retinopathy, floppy eyelid syndrome, keratoconus, and glaucoma.^3-6 Although some researchers have questioned the link between glaucoma and OSA, multiple recent studies continue to suggest an increased risk of glaucoma in individuals with OSA.^3,4,7-9 One study in particular demonstrated that patients with OSA exhibit thinning of the retinal nerve fiber layer (RNFL), and that severity of thinning correlated with increasing severity of OSA.⁸

Patients with moderate and severe OSA have also been shown to exhibit higher IOP than patients with mild OSA,⁸ and patients with OSA with clinically normal optic disc appearance have demonstrated significant decreases in RNFL thickness, ganglion cell layer thickness, and optic nerve rim area compared with age-matched controls.⁹ When placed under 24-hour IOP monitoring, patients with OSA experienced significant IOP increases while sleeping compared with those who do not have OSA; moreover, increases correlated directly with disease severity and inversely with oxygen saturation levels.¹⁰

Studies of visual fields in patients without a history of glaucoma have demonstrated higher pattern standard deviation and significantly lower mean deviation values in patients with OSA, with higher pattern standard deviation values in patients with more severe OSA.¹¹ It has also been demonstrated that hypoxia due to OSA causes swelling of retinal cell ganglion cell bodies and a temporary increase in macular thickness, leading to cell death and significantly lower ganglion cell complex thickness values compared with controls.^5,9,12 In addition, the incidence of suspicious discs with glaucomatous changes is four times higher in patients with OSA compared with controls.¹³ Another study determined that the lamina cribrosa is significantly thinner in patients with OSA,¹⁴ and researchers have also demonstrated that individuals with OSA exhibit decreased peripapillary RNFL thickness and increased optic nerve head parameters.¹⁵

WHAT SHOULD WE DO WITH THIS INFORMATION?

While a connection between OSA and glaucoma is suggested in the literature, proper treatment of OSA, combined with ophthalmic care, has been shown to result in better control of glaucoma.¹⁶

Eye care professionals must take steps to ensure that patients receive the care they need. First, remember that most cases of OSA in the United States are undiagnosed. As primary care providers, we should be aware of the signs and symptoms of this condition and its effects on the body and the eyes. Incorporating simple questions into your patient workup can help to screen for OSA. If a patient confirms a prior diagnosis of OSA, ask whether they are compliant with treatment and follow-up plans, and remind them of the importance of doing so. Inform patients about the ocular effects of OSA—they will likely be surprised to learn it can affect their eyes.

BE PREPARED TO COUNSEL YOUR PATIENTS

Given the evidence in the literature, it makes sense to treat OSA as an independent risk factor when evaluating patients with glaucoma and patients who are glaucoma suspects. Modifiable risk factors for OSA overlap with many eye conditions; therefore, we should be prepared to counsel patients on the importance of maintaining healthy habits, such as avoiding smoking and maintaining a healthy BMI. Eye care professionals should be prepared to engage with other primary care providers or specialists to coordinate care. Taking these suggested steps will help to ensure the overall well-being of patients who depend on us.