In vivo real time wavefront sensorless adaptive optics optical coherence tomography for mouse retinal imaging and visualization of the response to laser exposure

Abstract

 

Purpose

 

In vivo visualization of cellular-level retinal structure with adaptive optics optical coherence tomography (AO OCT) will enable studies of changes in the retina preceding vision loss in mouse models of diseases causing blindness. Wavefront sensorless adaptive optics (WSAO) OCT simplifies the optical design and eliminates the need for wavefront sensing, which is difficult in the small eyes of mice and in particular albino strains. The dynamic response of the retina to the laser exposures is studied in mice in real time with the high speed WSAO OCT system.

 

Methods

 

TThe WSAO OCT was constructed based on our previously reported AO OCT system. As shown in the schematic in Fig 1, a 473 nm Diode-Pumped Solid-State laser was focused onto the retina to investigate the effects of laser exposures. A custom written GPU accelerated OCT processing program was modified to extract C-scans from a user selected retinal layer and calculate the image quality (merit function). Aberration correction was performed using modal based control of a deformable mirror for WSAO optimization. The high speed processing capability and the advanced control of OCT data acquisition allowed seamless switching between different acquisition parameters. During WSAO optimization, the OCT engine operated at 200 kHz A-scan rate, providing ~11 volumes per second with 1024*112*112 pixels. After optimization, the acquisition speed was reduced for higher image quality (sampling density). The estimated focal spot (Gaussian waist 1/e2) for imaging beam was 1.3 μm in air.

 

Results

 

WSAO OCT images were acquired in pigmented and albino mice. Representative images of mouse retina are shown in Fig 2 demonstrating the high resolution imaging capability of our WSAO OCT system. The dynamic retinal response to different exposures of the visible laser was visualized in real time with high resolution using the WSAO OCT.

 

Conclusions

 

We present a novel modal control WSAO OCT system for small animal retinal imaging, which enables wavefront sensorless aberrations correction for user-selected layers in real-time. In vivo retinal imaging of pigmented and albino mice is presented, and the image quality improvement resulting from AO correction is demonstrated.

 

 

Fig.1: WSAO OCT system schematic

 

 

Fig2. WSAO OCT images of the mouse retina (Top) nerve fiber layer and (Bottom) outer plexiform layer.

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 578 laser