A man experienced a stroke in the tiny artery in his optic nerve and a neuro-ophthalmologist says sleep apnea that likely contributed to the stroke, reports CBS New York.

“The hypothesis is that with sleep apnea, the airways collapse. There is not enough oxygenation throughout the body,” Dr. Banik said.

“When that lack of oxygen and potential lack of perfusion can cause the nerves to swell. The nerves begin to swell and then some nerves begin to become damaged and the permanently damaged and that is when the vision loss happens.”