Calcium deposition as a cause of spoilation of hydrophilic soft contact lenses.

A series of 75 spoilt soft lenses with opacities (mostly manifesting as discrete spots or as large areas of cloudiness, chalk-white in appearance) were subjected to histochemical, electron microscopical, electron probe x-ray microanalytical, x-ray diffraction, atomic absorption spectro-photometric, and biochemical analyses. The results showed that in many cases calcium was implicated in the deposit formation and that a broad correlation existed between the amount of calcium present and the degree of opacification. The possible mode of calcium deposition and resulting implications in lens intolerance are discussed. It is advocated that a search should be made for a modified or new soft lens material which does not permit calcium deposition, and that the medical practitioner should strive towards improved assessment of the systemic and ocular conditions which may help in identifying patients at risk of early lens failure.