[Higher-order aberrations in myopic and astigmatism eyes].

OBJECTIVE

To analyze the distribution of the higher order aberrations in the population of Chinese with myopia and astigmatism and determine whether the pupil size, degree of myopia and astigmatism affects the higher order aberrations.

METHODS

Using a Tscherning method, 147 myopic and astigmatism eyes were evaluated before LASIK. The root mean square (RMS) values of higher order aberrations for each subject with pupil diameters of 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0 mm were calculated. The subjects were divided into following groups: high myopia (> -6.00 D) and low myopia (<or= -6.00 D); astigmatism group I (>or= 0.75 D) and astigmatism group II (< 0.75 D).

RESULTS

The root mean square (RMS) values was decreased from 3rd order to sixth order aberrations in the same eye. The individual difference was from 6.1-fold to 36.6-fold in same type of aberration. All types of aberrations, in particular spherical and coma aberration, was increased significantly with increasing pupil size. Secondary spherical aberration, spherical and secondary coma aberration were affected by myopia, but coma aberration; astigmatism only affected the coma aberration, but spherical aberration.

CONCLUSIONS

The aberrations were increased with the increasing of refractive error such as myopia and astigmatism. Spherical aberration is more common in high myopia, Coma aberrations is related with astigmatism.