Changes of ocular higher order aberration in on- and off-eye of rigid gas permeable contact lenses.

PURPOSE: To investigate ocular higher order aberration (HOA) changes caused by rigid gas permeable (RGP) contact lens (CL) wear. METHODS: Twenty-two eyes of 22 myopic patients and 14 eyes of 14 keratoconic patients who were fitted with an RGP CL were enrolled to examine ocular HOAs using a Hartmann-Shack wavefront sensor before and after RGP wear. Root mean square (RMS) values and Zernike coefficients in RGP-on and RGP-off eyes were compared for both myopic and keratoconic eyes, or between patient groups divided according to their prefitted total HOA value (RMS<0.33 microm or>or=0.33 microm in myopic eyes and RMS<0.46 microm or>or=0.46 microm in keratoconic eyes). All HOA values were recomputed for a 4-mm pupil for comparison purposes. RESULTS: In keratoconic eyes, RGP CL changed the direction of vertical coma from -0.185 to 0.134 microm (p=0.024). In the low HOA myopic group, total HOA increased from 0.23 to 0.35 microm (p=0.006) by RGP CL wear, mainly due to increased coma aberration from 0.0951 to 0.2146 microm (p=0.006). The direction of vertical coma changed from the inferior to superior cornea in the low HOA group (p=0.020). In the high HOA keratoconic group, total HOA decreased from 0.54 to 0.36 microm (p=0.049), and the direction of the vertical coma changed from the inferior to superior cornea (p=0.049). CONCLUSIONS: RGP CL wear may enhance or reduce HOA based on original existing ocular aberration mainly through directional changes in vertical coma.