Abstract： Objective:To observe the efficacy and safety of urokinase arterial thrombolysis in the treatment of central retinal artery occlusion (CRAO) at different time window.Methods:A retrospective study. From January 2014 to November 2019, 157 eyes (157 CRAO patients) in the Xi’an People's Hospital (Xi’an Fourth Hospital) were included in the study. There were 120 males and 37 females, with the average age of 54.87±12.12 years. The mean onset time was 65.66±67.44 h. All patients were tested with BCVA using international standard visual acuity chart, and the results were converted into logMAR visual acuity record. The arm-retinal circulation time (A-Rct) and the filling time (FT) of retinal arterial trunk-terminal filling time were measured by FFA. The mean logMAR BCVA was 2.44±0.46, the mean A-Rct and FT were 27.72±9.78 and 13.58±14.92 s respectively. According to the time window, the patients were divided into the onset 3-72 h group and the onset 73-240 h group, which were 115 patients and 42 patients respectively. There were no statistically significant difference between the 3-72 h group and the 73-240 h group in age, A-Rct and LogMR BCVA before treatment ( χ2=-0.197, -1.242, -8.990; P=0.844, 0.369, 0.369); the difference was statistically significant in FT comparison ( χ2=-3.652, P=0.000). Urokinase artery thrombolytic therapy was performed at different time window of 3-24 h, 25-72 h, 73-96 h, 97-120 h, 121-240 h after the onset of onset. Age and A-Rct of patients with different treatment time windows were compared, and the differences were not statistically significant ( χ2=6.588, 6.679; P=0.253, 0.246).In comparison of FT and logMAR BCVA, the difference was statistically significant ( χ2 =30.150, 71.378; P=0.000, 0.000). FFA was rechecked 24 hours after treatment, BCVA was rechecked 30 days after treatment. The changes of A-Rct, FT and BCVA before and after treatment were compared and analyzed. The occurrence of adverse reactions during and after treatment were observed. The two groups of measurement data were compared. The t test was used for those with normal distribution and χ2 test was used for those with non-normal distribution. Spearman correlation analysis was used to analyze the correlation between onset time and the difference of A-Rct, FT shortening time and logMAR BCVA after treatment. Results:At 24 h after CRAO treatment, A-Rct and FT of 157 cases were 19.64±6.50 and 6.48±7.36 s respectively, which were significantly shorter than those before treatment, and the differences were statistically significant ( χ2=-16.236, -14.703; P=0.000, 0.000). The logMAR BCVA at 30 d after treatment was 1.72±0.76, which was significantly higher than that before treatment. The difference was statistically significant ( χ2=-14.460, P=0.000). After CRAO urokinase arterial thrombolysis at different time window, there were statistically significant differences in A-Rct shortening time, FT shortening time, and logMAR BCVA difference ( χ2=12.408, 24.200, 104.388; P=0.030, 0.000, 0.000). There was no statistically significant difference between the 3-72 h group and the 73-240 h group ( χ2 =-1.042, P=0.297) in shortening time of A-Rct after treatment. The difference of FT shortening time was statistically significant ( χ2=-3.581, P=0.000). The difference of logMAR BCVA was statistically significant ( χ2=-9.905, P=0.000). The results of Spearman correlation analysis showed that there was no correlation between the onset time and the shortening time of A-Rct and FT after treatment ( rp=-0.040, -0.081; P=0.436, 0.115), and negative correlation with the logMAR BCVA difference ( rp=-0.486, P=0.000). One case of intracranial hemorrhage occurred after treatment, and it improved after dehydration to reduce cerebral edema, scavenging free radicals and brain protection. Conclusions:Urokinase arterial thrombolytic therapy is effective for CRAO within time window of 3-240 h, A-Rct, FT and LogMRA BCVA are all improved. However, with the prolongation of thrombolytic therapy time window, the therapeutic effect of urokinase arterial thrombolytic therapy is decreased. The therapeutic effect of Urokinase arterial thrombolytic therapy was better within 72 h.