Abstract
Purpose: :
To develop a new generation AOSLO for in-vivo study of retinal structure and function at the cellular level and improve retina image fidelity.
Methods: :
A fast and sensitive Shack-Hartmann wavefront sensor was developed with a CMOS camera (MicroVista®-NIR, Intevac Inc. CA); its spectral response was optimized for both visible and near infrared light; it is able to capture the wavefront at the frame rate 120 Hz when the light power is at 0.5 nw which was estimated a typical level for wavefront detection in an AOSLO setting. This sensor was used to measure the eye wavefront and supply the feedback control information in the adaptive optics (AO) system for ocular aberration real time compensation. An electromagnetic deformable mirror (DM) (miraoTM 52-e, ImagineEyes, France) was adopted as the wavefront corrector in the AO system. This DM is driven by 52 actuators with maximum stroke up to 50 micrometers. The AO system was integrated with the scanning optics to form the AOSLO. Low coherence light sources were employed for high fidelity retinal imaging.
Results: :
The updating frequency of the AO loop is greater than 70 Hz in the human eye, while most previous reported AO for retinal imaging run under 30 Hz. For a 6 mm diameter pupil, after AO correction, the root-mean-square wave aberration was reduced to less than 0.1 micrometers.
Conclusions: :
We have implemented a new generation AOSLO that is highlighted with robust AO correction for the ocular aberration. The wavefront sensor developed in this study can not only facilitate a fast AO system but also be used as an independent instrument for measuring the ocular aberration dynamics during certain visual process. In-vivo study of retinal diseases and basic research with this AOSLO are underway.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • image processing • photoreceptors