Orbital vascular malformations: a consensus statement on terminology and its clinical implications. Orbital Society.

PURPOSE: Orbital venous anomalies and lymphangiomas have been generally classified on morphologic grounds. However, conflicting concepts of these lesions have hampered scientific dialogue and confused clinicians, with occasionally serious consequences for patients. As a step toward uniform nomenclature and better communication, a consensus on the terminology of orbital vascular malformations was sought among the members of the Orbital Society.
METHODS: A classification of orbital vascular malformations based on their hemodynamic relationships, as revealed by clinical and imaging features, was presented, discussed, and adopted at the 1998 Annual Meeting of the Orbital Society. A consensus statement was drafted and distributed to all members. The statement was then modified in accordance with members' responses, which included minor stylistic recommendations but no substantive dissent.
RESULTS: Orbital vascular malformations may be classified according to their hemodynamic relationships as no flow, venous flow, and arterial flow lesions. Assignment to each group is based on pertinent clinical and imaging criteria. Mixed forms with both venous and no flow components are grouped within the venous flow category to emphasize the clinical importance of that relationship.
CONCLUSIONS: A hemodynamic classification of orbital vascular malformations emphasizes features most germane to their management. It should reduce the clinical confusion resulting from purely morphologic differentiation. Widely accepted definitions may allow a better comparison of therapeutic protocols for these troublesome lesions.