BACKGROUND: It is generally accepted that the elevated calcium phosphate product in dialysis patients is associated with the development of extraskeletal calcification. There is, however, no clear association between the raised levels of calcium and phosphate ions and the degree of limboconjunctival calcification. This article focuses on the role of tissue devitalisation in the development of ocular calcification. METHODS: Local injury of the outer eye can be visualised by the Lissamine green staining test. We measured the pre- and postdialysis staining score in 38 dialysis patients. The differences between pre- and postdialysis tear fluid secretion and tearfilm stability were also assessed, as was the degree of limboconjunctival calcification. Serum calcium and phosphate levels were measured in all patients. RESULTS: In 14 of the 38 patients, demonstrable tissue injury was present as a result of a recurrent decrease of tear secretion after each dialysis session. There was a statistically significant association between the degree of limboconjunctival calcification and both the difference between the pre- and postdialysis Lissamine green staining score and the total number of haemodialysis sessions. CONCLUSION: Local factors, such as minor tissue injury of the limboconjunctival epithelium, referred to as "local challenger", are more likely to determine the degree of ocular calcification in dialysis patients than are systemic factors. Tissue injury of the outer eye in these patients is the result of a chronic decrease of tear fluid that occurs after each hemodialysis session.
BACKGROUND: It is generally accepted that the elevated calcium phosphate product in dialysis patients is associated with the development of extraskeletal calcification. There is, however, no clear association between the raised levels of calcium and phosphate ions and the degree of limboconjunctival calcification. This article focuses on the role of tissue devitalisation in the development of ocular calcification. METHODS: Local injury of the outer eye can be visualised by the Lissamine green staining test. We measured the pre- and postdialysis staining score in 38 dialysis patients. The differences between pre- and postdialysis tear fluid secretion and tearfilm stability were also assessed, as was the degree of limboconjunctival calcification. Serum calcium and phosphate levels were measured in all patients. RESULTS: In 14 of the 38 patients, demonstrable tissue injury was present as a result of a recurrent decrease of tear secretion after each dialysis session. There was a statistically significant association between the degree of limboconjunctival calcification and both the difference between the pre- and postdialysis Lissamine green staining score and the total number of haemodialysis sessions. CONCLUSION: Local factors, such as minor tissue injury of the limboconjunctival epithelium, referred to as "local challenger", are more likely to determine the degree of ocular calcification in dialysis patients than are systemic factors. Tissue injury of the outer eye in these patients is the result of a chronic decrease of tear fluid that occurs after each hemodialysis session.