Shape of the anterior surface of the cornea after extended wear of silicone hydrogel soft contact lenses.

PURPOSE

To measure geometrical changes in the anterior surface of the cornea after wearing silicon hydrogel (SiH) soft contact lenses continuously for 1 week.

METHODS

Forty-three eyes with 3.0D of myopia and 22 eyes with 3.0D of hyperopia were enrolled in the prospective, interventional study. All subjects underwent a general eye examination, corneal tomography with wavefront aberration analysis, corneal thickness measurements and epithelial thickness mapping before and after wearing SiH lenses (Acuvue Oasys) for 7 days.

RESULTS

No significant changes in average keratometry were observed in either refractive group. In the myopic group, keratometry findings for the flat meridian (K1) and central corneal thickness decreased significantly. After +3.0 D lens wear in the hyperopic group, a significant decrease in epithelial thickness up to 3.19 µm was observed in the central and paracentral cornea, (p < 0.001). In both refractive groups, the largest epithelial thickness increase was seen in the periphery. A decrease in spherical aberration was noted in myopic eyes, while an increase of both higher order corneal aberrations and coma was found in hyperopic subjects.

CONCLUSION

Extended wear of SiH lenses results in a significant change in epithelial thickness leading to alteration in the geometry of the anterior surface of the cornea, particularly in hyperopic patients. These epithelial thickness variations lead to changes in the higher order aberrations of the cornea.