Symptoms: sudden, painless unilateral vision lossFirst aid must be started as quickly as possible: firm finger pressure to the eye for about one minute followed by a sudden release (may also be instructed to the patient over the telephone; make sure the patient has not recently undergone eye surgery). Ocular massage may be continued until other treatment is initiated.At the first aid centre, aspirin 250 mg may be given.The patient must be sent immediately to an ophthalmic emergency department. Irreversible retinal damage starts to occur 1½ hours after the occlusion.Aetiological investigations are started as soon as possible after the detection of the occlusion, as is done with all other disturbances of the cerebral circulation as well.