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Sleep Apnea ....continued from page 7 Anterior ischemic optic neuropathy (AION) is sometimes

described as a "stroke of the optic nerve." It comes in two forms. The first form of AION – arteritic AION – results from of in-

flammation of cells (giant cells) of the carotid arterial system. When this system becomes inflamed, the optic nerve and retina – which are fed by branches from the carotid arteries – become prone to the consequences of the inflammation. One conse- quence is reduced blood flow. Transient blurring of vision oc- curs followed by permanent vision loss. The second form of AION – non-arteritic AION (NAION) –

results from a temporary drop in blood pressure. The drop in blood pressure is enough that the blood vessels supplying the optic nerve can not provide enough oxygen. Without sufficient oxygen, optic nerve tissue dies. On arising, people with NAION note worse problems with

vision (such as loss of peripheral vision, loss in distinguishing shades, and impaired depth perception). Scientists suspect this may be because blood pressure usually falls to its lowest during the night. The effects of sleep apnea on hemodynamics may pro- vide the conditions for eye damage in NAION. Papillema is a eye disorder that usually results from in-

creased intracranial pressure. Intracranial hypertension can be secondary to factors such as stroke, aneurysm, tumor or it can be idiopathic. Intracranial hypertension causes brain tissue to press against the optic nerve. The pressure prevents axoplasm in the optic nerve from flowing freely. The axoplasm builds up near the optic head (i.e., the portion of the optic nerve directly behind the eye). Objectively on ophthalmoscope examination, this process manifests as a swollen optic disc. Subjectively,

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symptoms of papilledema are a graying of vision especially on ris- ing or sitting up; transient flickering; blurring; constriction of visual field; and decreased color perception. Sleep apnea may worsen symptoms of papilledema due to a

common risk factor for sleep apnea: obesity. One thought is that increased abdominal tissue in an obese person results in increased intra-abdominal pressure. This, in turn, raises the pressure needed to fill the heart with blood. Increased cardiac filling pressure im- pedes the flow of venous blood as it returns to the heart from the brain. As a result, the venous blood builds up in the brain thereby increasing the intracranial pressure and resulting in papilledema. Diabetic retinopathy occurs in people with long-standing di-

abetes. Capillaries in the retina form small sac-like dilatations (i.e., microaneurysms) which break and leak fluid. In response, new capillaries form; these new capillaries, however, break and bleed more easily. This bleeding can impair vision. Later, fibrosis may occur causing the retina to detach resulting in blindness. Studies show that sleep apnea worsens diabetic retinopathy. It

may be that increased hemodynamic pressures that occur as a per- son struggles to breathe during an apneic episode may worsen the hemorrhaging that occurs in diabetic retinopathy. Scientists have noted that treating sleep apnea can reverse or

improve symptoms of glaucoma, AION, papilledema, diabetic retinopathy and other eye diseases. Mojon et al. in a 1998 study treated apneic subjects with continuous positive airway pressure (CPAP). The subjects suffered from visual field defects despite hav- ing normal ophthalmologic examination. The visual defects re- mained did not worsen during an 18 month period in most subjects treated with CPAP and even improved in one subject. Mojon et al. concluded that CPAP treatment may stabilize or reverse visual field defects resulting from sleep apnea. Andrew G. Lee et al. studied the effects of drug therapy only,

drug therapy plus CPAP treatment, or CPAP treatment only on 6 subjects with papilledema (resulting from intracranial hyperten- sion). All subjects had visual field defects before any treatment. After treatment (no matter the mode of treatment), five of the sub- jects had normal visual fields. Papilledema resolved in 3 subjects after treatment. These three, who were treated with drug therapy plus CPAP treatment, discontinued the drug therapy and stayed on CPAP alone. Lee et al. concluded that CPAP may improve symp- toms of intracranial hypertension and its subsequent symptoms (e.g., papilledema). Toshiaki Shiomi et al. report the case of a woman who had

glaucoma and sleep apnea as a result of Hallermann-Streiff syn- drome. Hallermann-Streiff syndrome is a congenital disorder in- volving

glaucoma in both eyes, microphthalmia

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[smaller-than-normal eyes], dwarfism, lower-than-normal amount of body hair, a characteristic "beak-shaped" nose, micrognathia, dental abnormalities, and increased upper airway resistance. Sh- iomi et al. found that treating the woman with CPAP therapy pre- vented a worsening of her glaucoma symptoms during a time she had to forgo taking her normal drug regimen for glaucoma. Physicians may need to check patients for sleep apnea who

have been diagnosed with diseases that affect the vascular or neu- ral tissues of the eye such as glaucoma, AION, papilledema, and retinopathy. Treating sleep apnea may save a patient’s sight, reverse symptoms, or at least stall the worsening of symptoms.

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