Spherical aberration yielding optimum visual performance: evaluation of intraocular lenses using adaptive optics simulation.

PURPOSE: To evaluate the influence of spherical aberration on contrast sensitivity using adaptive optics.
SETTING: Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California, Davis Medical Center, Sacramento, California, USA.
METHODS: Contrast sensitivity at 8 cycles per degree was evaluated using an adaptive optics system that permitted aberrations to be measured with a Hartmann-Shack wavefront sensor and controlled by a 109 actuator continuous-surface deformable mirror that was at a plane conjugate to the observer's pupil. Vertical Gabor patches were viewed through a 6.3 mm diameter pupil conjugate aperture. Contrast sensitivity was measured with the deformable mirror set to produce 1 of 5 spherical aberration profiles (-0.2 to +0.2 microm). Contrast sensitivity over the range of spherical aberration was fitted with a polynomial function.
RESULTS: Three subjects (age 21 to 24 years) participated. The measured total mean spherical aberration resulting from the spherical aberration profiles produced by the deformable mirror was between -0.15 microm and +0.25 microm. The peak contrast sensitivity of this function for the 3 subjects combined occurred at +0.06 microm of spherical aberration. The peak contrast sensitivity was also achieved with positive spherical aberration for each subject's data fitted individually (mean 0.09).
CONCLUSION: There was intersubject variability in the measurements; however, the mean visual performance was best with the introduction of a small positive spherical aberration.