Ultrastructural studies of corneal collagen during the development of experimental scleritis in rabbits.

An active Arthus reaction induced in the rabbit cornea leads to scleral disease resembling that in humans. Collagen damage was located in the corneal stroma at the site of the immune reaction. In the electron microscope, some regions of corneal stroma, without loss of lamellar integrity, demonstrated the apparent swelling of individual, scattered collagen fibrils such that a helical arrangement of component microfibrils was evident. In areas showing more extensive damage, fibril fragmentation and solubilization was associated with the aggregation of fibrous banded material. These observations are discussed with reference to possible mechanisms underlying the development of scleritis in the rabbit and which might also contribute to an understanding of the pathology of the disease in humans.