PT - JOURNAL ARTICLE AU - A F Winder AU - M Ruben AU - G A Sheraidah TI - Tear calcium levels and contact lens wear. AID - 10.1136/bjo.61.8.539 DP - 1977 Aug 01 TA - British Journal of Ophthalmology PG - 539--543 VI - 61 IP - 8 4099 - http://bjo.bmj.com/content/61/8/539.short 4100 - http://bjo.bmj.com/content/61/8/539.full SO - Br J Ophthalmol1977 Aug 01; 61 AB - Hydrophilic contact lens spoliation can be associated with the deposition of calcium salts. The relationship between the concentration of calcium in tear fluid and contact lens use has been studied in healthy volunteers and in patients using various forms of hard and soft contact lenses, tear samples being collected with Schirmer strips and with lenses in situ. Methods are suggested for correcting data on calcium per strip to concentration when this cannot be directly determined. Further data were obtained by direct extraction of freshly removed soft contact lenses. The collected results indicate some variation in tear calcium concentrations, but values are unrelated to use of contact lens and type of lens fitted, and to the rates of tear flow with our procedures for collection. Local calcium concentrations are unlikely therefore to be a significant primary factor in soft contact lens spoliation, but the enlargement of the tear pool associated with the use of a soft contact lens does greatly increase the amount of calcium present, and this may be a factor in secondary deposition.