Abstract
Purpose: :
Intra-ocular lens (IOL) with negative spherical aberration has been recently used in cataract surgery for compensating positive spherical aberration in the cornea. Purpose of this study is to measure spherical aberration of the IOL with negative spherical aberration design and also the conventional IOLs which are supposed to have positive spherical aberrations.
Methods: :
A Hartmann-Shack wavefront sensor was constructed to measure wavefront aberration of IOL in-air, and spherical aberration was derived from Zernike aberrations, which were decomposed from the wavefront aberration. Two types of 20D IOLs with negative spherical aberration design from two different companies were compared with two conventional IOL types from the same companies, and a series of conventional IOLs with different powers from another company were also measured.
Results: :
The two IOLs with negative spherical aberrations were found to have negative spherical aberrations of -2.07 and -3.04 µm respectively, as compared to two conventional IOL types with 1.08 and 0.50 µm positive spherical aberrations from the same companies. Positive spherical aberration was observed for a series of IOLs with conventional design (15D to 25D) and the spherical aberrations was positively correlated to IOL powers (r= 0.92, p<0.0005).
Conclusions: :
The results indicate that IOL with conventional design has positive spherical aberration and with the amount of spherical aberration proportional to IOL power. Negative spherical aberration in the IOL with the new design might be useful to compensate positive spherical aberration in the cornea.