Obstructive sleep apnea (OSA) is now a suspected risk factor for glaucoma and other optic nerve diseases, according to a recent review of the topic in the Canadian Journal of Ophthalmology.1 But more study is needed to determine how much of a risk it may be.
There are several features of OSA that could potentially affect the health of the optic nerve, according to Sukhjeet Dhillon, MSc, from the University of Waterloo School of Optometry, and colleagues who wrote the paper. Sleep-disordered breathing is a common disorder that has been increasingly associated with eye diseases. [It] may make the eye vulnerable due to the effect of hypoxia or it can involve pathways that lead to impaired autoregulation of optic nerve perfusion, they wrote. The authors did not respond to requests for interviews.
The review included more than 30 studies in the medical literature, some of which supported a possible link between OSA and eye disease, although others found the association between the two weak.
OSA occurs in an estimated 9% of women and 24% of men between the ages of 30 and 60 years. However, those rates may be low, and an estimated 80% to 95% of OSA cases remain undiagnosed, the study said. OSA consists of repeated episodes of partial or complete obstruction of the airways during sleep. Apnea can lead to hypoxia, hypercapnea, blood pressure fluctuations, and possible changes in ocular hemodynamics, the authors noted.
Some studies suggest there are increased rates of snoring, insomnia, and excessive daytime sleepiness (symptoms typical of OSA) in patients with primary open angle glaucoma. Yet another study showed the greater the number of apneas OSA patients exhibited, the greater the increase in intraocular pressure (IOP), visual field loss variance, and glaucomatous optic disk changes.
However, some studies did not find a strong correlation between glaucoma and OSA, so strong conclusions cannot be made. But this warrants more study, the authors said.
OSA and Papilledema
Papilledema has suspected links to both apnea and hypoventilation. Here, studies suggest that hypoxia and hypercapnia caused by the breathing abnormalities raise intracranial pressure by causing vasodilation in the cerebral artery. The authors found one small study in which 33% of patients with intracranial hypertension had OSA and noted that their symptoms improved after being treated for apnea.
Although it has been suggested that intermittent apneic episodes lead to a deterioration of visual function and (or) ischemic damage to the optic nerve, one cannot rule out the possibility that the relation is mediated by additional factors, the authors wrote. In other words, apnea could be one of several contributing factors to vision problems in some patients.
Otolaryngologists Comment on the Study
Edward M. Weaver, MD, Associate Professor of Otolaryngology and Chief of Sleep Surgery at the University of Washington in Seattle, was not particularly surprised by the study’s findings. He was not part of the study group, but noted that the possible effect of obstructive sleep apnea on ocular disease is another interesting relationship that deserves further investigation. There is growing evidence of many effects of obstructive sleep apnea on other organ systems-for example, on the cardiovascular, endocrine, metabolic, renal, cognitive, and now ocular systems.
The article provides a good summary of preliminary data in the literature that begin to support a relationship between obstructive sleep apnea and specific ocular disorders, and it hypothesizes the pathophysiological mechanisms, he said. OSA has effects on various physiological mechanisms that may affect various organs and physiological systems. Transient changes in blood pressure, intermittent hypoxia, and sympathetic activation are only some of the possible mechanisms OSA could damage.
Tod C. Huntley, MD, from Head & Neck Surgery Associates in Carmel, IN, who treats a large number of OSA patients, agrees that the topic deserves further study. It is well known that obstructive sleep apnea can have wide-ranging effects on other body systems. The relationships between OSA and hypertension, heart disease, and stroke, for example, are well established and have been studied extensively. The effects that OSA may have on ocular health are less well known but are very intriguing, he told ENToday in an interview.
The CJO article included studies investigating OSA and various eye problems including glaucoma, nonarteritic anterior ischemic optic neuropathy, visual field defects, papilledema, and more. The effects of OSA on body homeostasis provide insight into how OSA can play a role in the pathogenesis of ocular dysfunction. The immediate physiological effects of OSA involve hypoxia, hypercapnia, and inspiratory effort. These factors may directly impact the functioning of the optic nerve or work in concert to manifest as vascular sequelae, the authors wrote.
From an ophthalmology perspective there aren’t enough data to support changes in the management of patients with eye disease and OSA, but there are enough compelling data to warrant further study, according to Graham Trope, MD, an ophthalmologist at the University of Toronto. He was not one of the study authors.
However, he added that if ophthalmologists have patients who are middle-aged and overweight-that is who are OSA suspects-it’s worth referring them for a sleep assessment. It’s certainly worth sending them for sleep assessment because it wi’ll help their sleep problems. Whether it will help their glaucoma, we don’t know at this time, he said.
But it is possible that otolaryngologists and ophthalmologists may find themselves working together a bit more in the future.
- Dhillon S, Shapiro CM, Flanagan J. Sleep-disordered breathing and effects on ocular health. Can J Ophthalmol 2007;42:238-43.
©2007 The Triological Society