High Quality Content by WIKIPEDIA articles! Long-term contact lens use leads to alterations in corneal thickness, stromal thickness, curvature, corneal sensitivity, cell density, and epithelial oxygen uptake, etc. Other changes include the formation of epithelial vacuoles and microcysts (containing cellular debris) as well as the emergence of polymegathism in the corneal endothelium. Decreased corneal sensitivity, vision loss, and photophobia have also been observed in patients who have worn contact lens for an extended period of time. Surprisingly, many contact lens-induced changes in corneal structure are reversible if contact lenses are removed for an extended period of time.