Efficacy of Oral Sirolimus Therapy for Adult Orbital Slow-Flow Vascular Malformations: A Volumetric Evaluation

Orbital lymphatic malformations significantly impair visual function, with inflammation contributing to corneal dryness and diplopia due to exophthalmos. Disease progression may lead to blindness, and in severe cases, exenteration may be required. We treated two symptomatic cases of adult orbital slow-flow vascular malformations with oral sirolimus. Although the patients maintained good visual acuity before treatment, prominent exophthalmos posed a substantial risk to visual function. After medication, eyeball proptosis improved significantly in all cases, with magnetic resonance imaging volumetry analysis showing a reduction of 28.5% to 82.1%. This treatment demonstrated minimal side effects and may serve as an initial therapeutic option.