Optic disc edema in astronauts after long-duration missions to the International Space Station was first described in 2011, and National Aeronautics and Space Administration (NASA) now describes this as spaceflight-associated neuroocular syndrome (SANS).

 

Clinically, SANS is defined solely on the basis of optic disc edema, although there are other associated ocular findings, including globe flattening, choroidal and retinal folds, hyperopic shift, and cotton wool spots.

 

In traditional medical education, optic nerve head swelling is essentially and wrongly associated with only increased intracranial pressure (ICP).

 

However, ophthalmic education clearly distinguishes papilledema (disc edema caused by increased ICP) from optic disc edema in general, which can arise from many etiologies.