• The effect of years of wear of hard contact lenses on corneal sensitivity has been evaluated. By testing 91 subjects who had worn lenses for up to 22 years and a control group of 42 people, it was found that corneal sensitivity diminished exponentially. However, in five subjects who had abandoned use of their lenses, recovery occurred within four months, indicating that the process is reversible. The loss of corneal sensitivity with hard contact lens wear ought to be heeded, since the eye is thus at a greater risk of infection.
Millodot M. Effect of Long-term Wear of Hard Contact Lenses on Corneal Sensitivity. Arch Ophthalmol. 1978;96(7):1225–1227. doi:10.1001/archopht.1978.03910060059011