UC Davis

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.