Abstract
Purpose :
We present the recent progress on wavefront sensorless adaptive optics (WSAO) for pre-clinical retinal imaging with optical coherence tomography (OCT), florescence confocal scanning laser ophthalmoscope (fcSLO) and simultaneous OCT two-photon biomicroscopy (OCT-TPM). In vivo retina structural and functional images acquired with mice are presented.
Methods :
Wavefront Sensorless adaptive optics (WSAO) has been demonstrated to be a robust strategy for circumventing the limitations associated with conventional AO systems using a Shack Hartmann wavefront sensor. Instead of measuring the wavefront aberrations, it directly uses the image quality metric such as brightness and sharpness as a merit function for aberration correction. It is especially advantageous in small animal retinal imaging with lens-based imaging systems when wavefront sensing is difficult and inaccurate. In our WSAO imaging systems, we employed a modal hilling climbing algorithm, where the deformable element steps through Zernike modes with a preset range of coefficients, while the image quality metric is recorded, the coefficients that resulted the image with best quality is then applied to the deformable optical element.
Results :
We present images of mouse retina acquired with our second generation WSAO OCT using a large stroke ALPAO mirror. The OCT volumes were streamed during acquisition and then averaged in post processing. Using a collimated beam incident on the eye with a zero diopter contact lens, the defocus could be shifted from retinal vasculature to the outer retina for visualization of the mouse photoreceptor mosaic. We present progress on widefield and high resolution mouse fluorescent retinal imaging using a zero diopter contact lens. Defocus was controlled using a variable focus lens, and aberration correction was performed with an IrisAO MEMS segmented deformable mirror.
Conclusions :
In conclusion, WSAO techniques enable high resolution retinal imaging in preclinical applications at a reduced cost and system complexity. Combination of WSAO-OCT with a TPM system will enable depth resolved aberration correction based on structural images prior to the acquisition of low intensity functional images.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.