Optic nerves at risk for A.I.O.N. have no central cup . Treatment , if any , for A.I.O.N. is controversial . Because temporal arteritis , which is clearly treatable with steroid medications , is sometimes confused with A.I.O.N. , a more thorough investigation may be needed to distinguish between these two disease entities . Retinal Artery Occlusions Retinal artery occlusions can involve either the central retinal artery or smaller branch retinal arteries . Retinal artery occlusions are another cause of sudden , painless vision loss in one eye .
Some inflammatory diseases affecting small arteries can lead to arterial occlusion .
Other examples are polyarteritis nodosa , and Behcet's disease . Blood clots can form on diseased arterial walls or diseased heart valves , and small pieces of clot can break off and float in the bloodstream , until they become lodged in retinal arteries . Similarly , cholesterol plaque formations on the walls of diseased carotid arteries in the neck may break off and flow through the bloodstream until they become lodged in smaller retinal arteries . Patients may experience transient , recurrent visual loss symptoms as a precursor for a major event with resulting permanent visual loss from an arterial occlusion . Transient visual loss with darkening of vision in one eye lasting generally a few minutes or less than one hour is termed ' amaurosis fugax ' or ' transient visual obscurations ' .