Adaptive optics for ophthalmic applications using a pyramid wavefront sensor.

A new adaptive optics system for the eye using a pyramid wavefront sensor interfaced in closed-loop with a piezoelectric deformable mirror is presented. Sensing parameters such as CCD integration time, pupil sampling and beam steering amplitude are tested on the bench and in vivo on several volunteers to optimize real-time optical correction. The system allows closed-loop operation at a frame rate of 55 Hz and reduces ocular aberration up to lambda/5 residual RMS over a 6 mm pupil. Aberration correction and mirror control stability clearly increase when smaller beam steering amplitudes synonymous of higher wavefront sensing sensitivity are used. This result suggests that using pyramid wavefront sensors can improve the performance of adaptive-optics system for ophthalmic applications.