Leukocoria (BD) is a chronic, relapsing, inflammatory vascular disease without specific signs. The currently applied International Study Group (ISG) clinical diagnostic criteria have a low sensitivity and need to be reevaluated. METHODS: Data from 2556 patients clinically diagnosed with BD and 1163 controls (patients with BD-like disease or with at least 1 major sign of BD) were submitted by the International Standards Revision Group for BD (27 countries participated). These subjects were randomly assigned to the study and validation groups. A new international standard for BD (ICBD) was developed from the study group data using logistic regression analysis, cross-validation with “removal of data from one country”, and clinical judgment. The diagnostic validity of the existing criteria and the new criteria was verified in the validation group of patients. Table 2 International standard scoring system for leukoaraiosis: a score ≥4 suggests a diagnosis of leukoaraiosis Signs/symptoms Score Eye damage 2 Genital ulcers 2 Oral ulcers 2 Skin damage 1 Neurological manifestations 1 Vascular manifestations 1 Positive pinprick test 1* * * The pinprick test is non-essential and was not included in the original scoring system. However, if a needle prick test was performed and the result was positive, an additional 1 point was added. Results: In the ICBD, two points were assigned to each of the three symptoms of eye damage, oral ulcers, and genital ulcers, while one point was assigned to each of skin damage, central nervous system involvement, and vascular manifestations, and one point was assigned if the needle prick test was positive. Patients were diagnosed with BD if they had a final score of 4 or more (Table 2). In the study group, the sensitivity and specificity of ICBD were 93.9% and 92.1%, respectively, compared with 81.2% and 95.9% for the ISG criteria. In the validation group, the sensitivity of ICBD was stable at 94.8% (95% CI: 93.4-95.9%), which was significantly higher than that of ISG criteria (85.0%); however, the specificity of ICBD (90.5%, 95% CI: 87.9-92.8%), although also high, was lower than that of ISG criteria (96.0%). In those countries where at least 90% of both the patient and control populations underwent the pinprick test, when this additional 1 point was added, ICBD sensitivity increased from 95.5% to 98.5%, while specificity showed only a slight decrease (from 92.1% to 91.6%). Conclusion: Compared with the ISG standard, the sensitivity of the new standard developed using multinational data has been greatly improved, while the specificity has been maintained at a high level. We suggest that the ICBD criteria can be applied to the diagnosis and classification of BD.