Adding the third dimension on adaptive optics retina imager thanks to full-field optical coherence tomography Marie Blavier ab , Leonardo Blanco ab , Marie Glanc ad , Florence Pouplard b , Sarah Tick b , Ivan Maksimovic ab , Laurent Mugnier cd , Guillaume Chènegros c , Gérard Rousset ad, , François Lacombe e , Michel Pâques b , Jean-François Le Gargasson b , José-Alain Sahel b a LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris Diderot, 5 Place Jules Janssen, 92190 Meudon, France b Centre d’Investigations Cliniques du CHNO des Quinze-Vingts, Université Paris VI, 28 rue de Charenton, 75571 Paris cedex 12, France c DOTA ONERA, BP 72, 29 avenue de la Division Leclerc, 92322 Châtillon cedex, France d Groupement d’Intérêt Scientifique PHASE (Partenariat Haute résolution Angulaire Sol Espace) between ONERA, Observatoire de Paris, CNRS and Université Paris Diderot e Mauna Kea Technologies, 9 rue d’Enghien, 75010 Paris, France ABSTRACT Retinal pathologies, like ARMD or glaucoma, need to be early detected, requiring imaging instruments with resolution at a cellular scale. However, in vivo retinal cells studies and early diagnoses are severely limited by the lack of resolution on eye-fundus images from classical ophthalmologic instruments. We built a 2D retina imager using Adaptive Optics to improve lateral resolution. This imager is currently used in clinical environment. We are currently developing a time domain full-field optical coherence tomograph. The first step was to conceive the images reconstruction algorithms and validation was realized on non-biological samples. Ex vivo retina are currently being imaged. The final step will consist in coupling both setups to acquire high resolution retina cross-sections. 1 INTRODUCTION Adaptive Optics (AO) has been used for more than a decade to compensate for ocular aberrations 1 , allowing new kinds of retinal imaging instruments with a high lateral resolution 2,3,4 . A few years ago, we developed an AO setup for 2D high lateral resolution imaging of the human retina 5 . It is now installed at the Quinze-Vingts Hospital and regularly used to image and obtain quantitative data on healthy and pathological eyes. However, axial resolution in depth is not sufficient to reconstruct retina in 3D. Optical Coherence Tomography (OCT) is an interferometric technique allowing the non invasive extraction of sectional images in the sample. We are developing a time-domain full-field OCT setup, our final aim being to combine both methods, AO and OCT, in order to build a 3D high resolution imager for ophthalmic diagnoses. 2 2D RETINAL IMAGER REPORT 2.1. Setup description The AO system of our setup is comprised of a 32 X 32 subpupil Hartmann-Shack wavefront sensor (WFS) and a 52- actuator magnetic deformable mirror (DM). The AO loop frequency is 7Hz. Science camera is a 12 bit 1360 per 1092 pixel Q-Imaging Retiga. Imaging frequency also is 7Hz. The wavefront sensing illumination source is an 830nm Superluminescent Diode and the science retina illumination source is a 550nm mercury vapor arc lamp. The near-IR wavefront sensing source allows the subject to feel comfortable during aberration correction, the shorter science wavelength leading to a higher theoretical lateral resolution as well as a better blood vessel imaging capability. Science illumination is based on flashes obtained through a system of two shutters (flash duration: 1ms to 10ms). Wavefront sensing channel and science channel are synchronized so the position of illumination flash can be precisely set. Total delay between WFS acquisition and imaging flash is 85ms (WFS acquisition = 30ms, WFS CCD reading = 35ms, voltages computation = 5ms, DM actuator and membrane stabilization = 20ms). Imaging field of view is 1° on the retina (~300µm). The AO and imaging system are controlled through a custom LabVIEW interface. To select the retina zone to be imaged, the subject is asked to fixate a target made of a 7 LEDs in-line stick (each LED being separated by 0.64° from its neighbors). This fixation target can rotate around the first LED so that a field of ca 9 degrees in diameter, centered on the subject fovea, can be imaged. Calibration is performed to link the ON-LED to retinal image localization on both eyes, for example by looking at an OCT section of the subject’s eye to determine the retinal regions of interest.