– It Can Also Take Our Sight
By Kapil G. Kapoor, M.D.

Recently, increasing evidence is highlighting the importance of good sleep hygiene for our visual health. Our eyes need sleep with uninterrupted REM cycles to allow a system restart. In sleep apnea, the tissues of the throat collapse and occlude the airway, causing repeated interruptions leading to rapid drops in oxygen levels. The brain responds by releasing compensating circulatory hormones that cause rapid blood pressure spikes.

The retinal blood vessels are extremely sensitive to these fluctuations, putting them at risk of micro-infarct or occlusion – the equivalent of mini-strokes. Even more concerning, obstructive sleep apnea may have a triggering role in cases of retinal vascular occlusions, which may explain why many patients with retinal vascular occlusions notice visual loss upon awakening.

Mini-strokes can affect the microcirculation surrounding the optic nerve as well, known as ischemic optic neuropathy. A stroke at the level of the optic nerve undermines the main transmission pathway between the eye and the brain.  Research has linked oxygen and vascular irregularities secondary to sleep apnea as important risk factors for ischemic optic neuropathy.

Sleep apnea has also been associated with open-angle glaucoma, which puts the optic nerve at risk for damage due to elevated pressure within the eye. Chronically elevated intraocular pressure can lead to gradual loss of peripheral vision, and frequently goes undiagnosed until advanced stages.

The most classic ocular association with sleep apnea is floppy eyelid syndrome, almost universally present in apneic patients. The oxygen and breathing changes throughout the night lead to frequent positional shifts and repeated friction on the eyelids against pillows and blankets.  This mechanical stress leads to a breakdown in the structural tissues of the upper eyelids, which are no longer able to provide the support the eyes need for maintaining tear film – leading to chronic dryness, irritation, and sometimes blurred vision.

Sleep apnea has been further linked with acceleration of other retinal vasculopathies – notably diabetic retinopathy. Vascular damage inherent to retinal capillaries in diabetic retinopathy can be compounded by damaging factors released in obstructive sleep apneic episodes. These all accentuate hypoxia, a critical driving stimulus for diabetic macular edema and proliferative diabetic retinopathy, in which the retina produces new blood vessels to compensate for the decreased blood flow and oxygen levels.  This neovascularization can be sight-threatening, potentially resulting in vitreous hemorrhages or tractional retinal detachments, often requiring an increased treatment burden to preserve sight.

While our treatments for preserving sight continue to advance, with multiple options of anti-VEGF intravitreal injections, focal or panretinal photocoagulation laser treatments, and the latest equipment for microincisional sutureless surgery, it’s clear that more attention needs to be shifted toward prevention. As we understand the risks of sleep apnea more, we need to improve patient screening and lower our threshold for patients who may be at risk. Patients should be asked about gasping or choking while sleeping, loud snoring, or daytime sleepiness. Also, it’s critical to engage a family member in the screening process, as patients are often unaware that they snore.  Working together as a healthcare team will allow us to optimize treatment for these patients, preserve their sight, and give them all of the benefits of a good night’s sleep.

Kapil G. Kapoor, MD completed medical school at Ohio State University, residency at the University of Texas Medical Branch-Galveston and a fellowship at The Mayo Clinic.
Dr. Kapoor is a Board certified ophthalmologist specializing in vitreoretinal surgery.  www.wagnerretina.com.