Much attention has been given to the clinical and pathological events which occur following the injection of antigenic substances into rabbit cornea.1-6 Within five days following injection, conjunctival and limbal hyperemia develop, followed by diffuse corneal clouding. Histopathologically, the cornea shows edema and infiltration by lymphocytes and mononuclear cells. This tissue reaction has been shown to be a manifestation of delayed-type hypersensitivity according to the following criteria: the lack of circulating antibody, a delayed-type skin hypersensitivity to specific antigen, and the ability to passively transfer this tissue hypersensitivity only with whole lymphoid cells from the sensitized animal.
The initial conjunctival inflammation and corneal clouding disappear within one week, leaving a clinically normal eye. Between 12 and 18 days after injection, however, marked local inflammatory signs return, accompanied by corneal neovascularization and corneal clouding; and, depending on the dose of antigen initially injected, a white ring (Wessely ring) appears in
OLSON CL. Subconjunctival Steroids and Corneal Hypersensitivity. Arch Ophthalmol. 1966;75(5):651-658. doi:10.1001/archopht.1966.00970050653014