Extraskeletal calcification is a common complication of chronic renal failure. It is well known that in dialysis patients the elevated calcium phosphate product is associated with the development of corneal and conjunctival calcification, but there is no association between the degree of the calcifications and the levels of calcium phosphate product. This paper is supposed to present briefly the main hypothesis who explain the mechanism that generates the deposition of the calcium salts to the anterior segment of the globe.