In macular degeneration disease of the eye, we have studied the behaviour of vitro thrombocyte aggregation/deaggregation and ex vivo plasma beta-thromboglobulin level (Born aggregometer, RIA kit) during administration of an antiaggregant platelet drug (ticlopidine). We have observed the presence of a prothrombotic state that improves after 15 days of administration of drug. In fact platelet aggregation and beta-thromboglobulin level significantly decrease while thrombocyte deaggregation significantly increase. The correlations between deaggregation, aggregation and beta-thromboglobulin level suggest that the antiaggregant action of the ticlopidine is linked to the inhibition of platelet release reaction.