The pathology of soft contact lens spoilage

Our study of a random series of more than 300 spoiled soft contact lenses reveals that virtually all lenses currently in use for daily or extended wear are subject to deterioration due to extraneous deposits, physical and chemical changes in the lens material, and microbial invasion. Common causes include ocular secretions, finger dirt and cosmetics, disinfecting and cleansing techniques, environmental factors, manufacturing defects and polymer impurities, mechanical stress and breakage, as well as aging and decay of the lens material. Mucoprotein-lipid deposits, with or without calcium, and calcareous deposits constitute the major forms of lens spoilage. Removal of encrusted deposits leaves surface irregularities and matrix defects which facilitate secondary spoilage including microbial invasion, and such lenses should be discarded. As virtually no soft lens material currently in use is "safe" for extended wear, the practitioner must carefully evaluated and follow his patients to identify those at risk of lens failure and spoilage complications. To eliminate spoilage, new lens materials and improved manufacturing techniques are needed. In the interim, for many patients, an inexpensive disposable soft lens which can be easily replaced, perhaps weekly or bi-weekly, may be the answer.