Surface deposits on worn hard contact lenses

Giant papillary conjunctivitis (GPC) is associated with deposits on contact lenses. We used scanning electron microscopy to study the anterior surface of 30 hard contact lenses, both cleaned and not cleaned, worn by patients with GPC and with keratoconus and by asymptomatic subjects. Uncleaned lenses worn by asymptomatic subjects for one day had deposits on about 5% of the surface. In most cases, the deposits were removed completely by one cleaning. Uncleaned lenses worn by patients with GPC or keratoconus had deposits on about 90% of the surface. Most of these deposits were removed by one cleaning. However, residual deposits after cleaning were greater on lenses from patients with keratoconus than on those from patients with GPC. Lenses from asymptomatic subjects rarely had residual deposits after cleaning. We found that the types of deposits on worn soft and hard contact lenses are similar, that there are fewer deposits on hard lenses than on soft lenses, and that deposits on hard lenses, unlike those on soft lenses, generally can be removed by one cleaning.