Higher-order wavefront aberration and letter-contrast sensitivity in keratoconus.

AIMS: To evaluate the relation between higher-order aberration of the eye and contrast sensitivity function in eyes with keratoconus.

METHODS

In 22 eyes of 14 patients with keratoconus (age 30.5+/-8.4 years, means+/-SD) and 26 eyes of 13 normal controls (age 29.2+/-6.7 years), ocular higher-order wavefront aberration for a 6-mm pupil was measured with the Hartmann-Schack aberrometer (KR-9000 PW, Topcon). The root mean square (RMS) of third- and fourth-order Zernike coefficients was used to represent higher-order aberrations. The letter-contrast sensitivity was examined using the CSV-1000LV contrast chart (Vector Vision).

RESULTS

In the keratoconus group, the letter-contrast sensitivity showed significant correlation with third-order (Spearman's correlation coefficient r=-0.736, P<0.001) and fourth-order aberrations (r=-0.464, P<0.05). There was borderline correlation between log MAR BSCVA and third-order (r=0.413, P=0.070) and fourth-order aberrations (r=0.394, P=0.086). In the normal group, the letter-contrast sensitivity had no significant correlation with third-order (r=-0.170, P=0.411) and fourth-order aberrations (r=-0.088, P=0.673), and log MAR best spectacle-corrected visual acuity (BSCVA) showed no correlation with third-order (r=0.063, P=0.762) and fourth-order aberrations (r=-0.282, P=0.165).

CONCLUSIONS

In eyes with keratoconus, there is significant correlation between contrast sensitivity and ocular higher-order wavefront aberrations.