Aetiology of sympathetic ophthalmitis. 
The aetiology of sympathetic ophthalmitis is still unknown.  Recent investigations on patients and experimental studies on allergic uveitis in guinea-pigs suggest that sympathetic ophthalmitis may be due to delayed hypersensitivity to one of the retinal antigens associated with photoreceptor membranes (called the retinal 's' antigen).  It is postulated that a penetrating injury causes a reversal of normal tolerance by introducing an adjuvant effect from bacterial or viral contamination along with the release of the intraocular antigen.  The antigen then gains access to the regional lymphatics by way of the penetrating wound.  A specific cell-mediated immune response is then initiated followed by the onset of sympathetic ophthalmitis.