• Clinical observations have established that sympathetic ophthalmia (SO) develops after a penetrating wound but not subsequent to often more severe intraocular disturbances such as extensive photocoagulation. A feature of the penetrating wound that appears important in the pathogenesis of SO is the access it provides for intraocular antigens to reach regional lymph nodes. The intraocular compartment has no lymphatic drainage and appears to function like a number of alymphatic biologic sites. In an experimental model of SO, subconjunctival injection of retinal S antigen in one eye induced a bilateral sympathetic uveitis, whereas intraocular injection in one eye was ineffective in inducing sympathetic disease.