Evolution of soft contact lens coatings.

To investigate further the reported possibility that surface deposits on soft contact lenses contribute to giant papillary conjunctivitis, we performed scanning electron microscopy on 22 lenses worn for varying durations by a group including persons who had never worn contact lenses and asymptomatic persons who had, and on five never-worn lenses. Thirty minutes' wear resulted in covering of about 50% of the anterior surface with scattered cell-membrane-like and mucus-like material, with mucus-like material on top of cells in places. Eight hours' wear produced about 90% covering with more complex coatings. Routinely worn and cleaned lenses had still more complex coatings on more than 90% of the surface. Deposits were found on routinely worn lenses even after professional cleaning. We conclude that all worn soft contact lenses have coatings that become more complex with time and may never be removed completely.