Thyroid-associated orbitopathy (TAO) is a common manifestation of Graves' disease. The aim of the study was to assess the six percent of patients with TAO that develop dysthyroid optic neuropathy (DON), which is the most serious complication of TAO. As DON can cause permanent damage, it is essential to detect DON early when visual loss is still reversible. Color Doppler ultrasound is a noninvasive diagnostic method, which may be useful in early detection of DON. Thirty-six patients with confirmed Graves' disease and active TAO were included, 21 (58%) of them with early DON (eDON) and 15 (42%) free from any signs of eDON. All study patients underwent Doppler ultrasound examination to determine the blood flow rates in the internal carotid artery, ophthalmic artery, and central retinal artery. Study results showed color Doppler ultrasound examination to have a potential to detect orbital blood flow changes in patients with eDON. Early detection of DON may result in earlier treatment and prevention of permanent optic nerve damage.Key words: Graves' Ophthalmopathy; Graves' Disease; Optic Nerve Diseases; Ultrasonography, Doppler, Color; Optic Nerve InjuriesProblemi stitnjace i povezane orbitopatije (TAO) najcesca su manifestacija Gravesove bolesti. Cilj ove studije bio je objasniti 6% bolesnika s TAO kod kojih se razvila distiroidna opticka neuropatija (DON), koja je ujedno najozbiljnija komplikacija TAO. S obzirom na to da DON moze izazvati trajno ostecenje vida, vrlo ga je vazno rano prepoznati dok je vidna funkcija jos ocuvana i reverzibilna. Obojeni Dopplerov ultrazvuk je neinvanzivna dijagnosticka metoda koja je vrlo djelotvorna u ranom otkrivanju DON-a. U studiju je bilo ukljuceno 36 bolesnika s dijagnosticiranom Gravesovom bolesti i TAO-om, od kojih je 21 (58%) bolesnik imao rani DON (early DON, eDON), dok 15 (42%) bolesnika nije imalo znakova eDON-a. Svakom ispitaniku ucinjen je obojeni Dopplerov ultrazvuk kako bi se odredio stupanj protoka krvi (cirkulacije) u unutarnjoj karotidnoj arteriji, oftalmickoj arteriji i sredisnjoj retinalnoj arteriji. Rezultati su pokazali da pregled obojenim Dopplerovim ultrazvukom ima visok potencijal u ranoj dijagnostici promjena cirkulacije u orbiti kod bolesnika s ranim eDON-om. Rano otkrivanje DON-a moze pomoci u ranijem lijecenju i prevenciji trajnog ostecenja vidnoga zivca.Kljucne rijeci: Gravesova oftalmopatija; Gravesova bolest; vidni zivac, bolesti; ultrazvucno snimanje, kolor dopler; vidni zivac, ozljede