Can hydroxyapatite deposition in the eye cause a neutrophil-related inflammatory reaction?

Patients with chronic renal failure on intermittent dialysis sometimes develop an acute diffuse conjunctival and episcleral hyperaemia. In this study the hypothesis was tested whether the precipitation of hydroxyapatite crystals could result in an inflammatory reaction mediated by enzymes liberated from polymorphonuclear leucocytes (PMN). Ingestion of the crystals by PMN's can result in cell death and membranolysis and subsequent release of intracellular enzymes into the surrounding tissues. This 'suicide sac' hypothesis for the inflammatory reactions of the conjunctiva and episclera was rejected after histopathological examination of conjunctival biopsies failed to show complement activation or crystal ingestion by PMN's despite the presence of small subepithelial hydroxyapatite crystals.