Adaptive optics assisted and optical coherence tomography guided fs-laser system for ophthalmic surgery in the posterior eye

Abstract

Abstract. While fs-lasers are clinically established for surgery in the anterior eye, their use in the posterior eye is impeded by aberrations and focus position errors. We implemented a laboratory system to investigate whether fs-laser surgery in the posterior eye is made more feasible by aberration correction and tomographic image guidance. Aberration correction is obtained by adaptive optics (AO) and the image guidance is accomplished by optical coherence tomography (OCT). System characteristic measurements and cutting experiments were performed inside an eye model. By aberration correction, wavefront errors were reduced from 270 nm root-mean-square (rms) to 64 nm rms, ignoring Zernike terms for tilts and focus. The Strehl ratio of the assigned point spread function is improved from 0.11 to 0.78. The threshold pulse energy of laser-induced optical breakdown in water is lowered from about 3.0 to about 1.3 μJ measured at the eye model entrance. After laser cutting of a synthetic foil placed 300 μm in front of porcine retinal tissue with the corrected system, postoperative three-dimensional OCT imaging showed no lesions in the tissue. Our results corroborate that AO and OCT will be two essential assistive components for possible clinical systems for fs-laser–based surgery in the posterior eye.