Imaging correlography applied to high resolution retinal imaging

The resolution of the images obtained from the eye fundus are limited by the ocular aberrations. As most of theaberrations are due to the eye optics, they do not affect the light intensity measured in the eye iris plane. By illuminating the retina with a laser and collecting the light in a pupil plane conjugate, it is possible to apply the imaging correlography technique. From processing series of pupil plane images, this technique gives information about the retina in the form of the squared modulus of the Fourier transform or, equivalently, the autocorrelation of the diffraction-limited image intensity. Two factors make this technique suitable for retinal imaging: 1) For this technique to work, changes of phase distribution in the retinal plane are necessary between each frame. Small eye movements naturally provide these changes; 2) This method does not provide directly the phase of the Fourier transform. Therefore it is of most use for centro-symmetric objects like the retina's photoreceptor mosaic. Preliminary data have been obtained in vivo showing the feasibility of applying such a technique in the eye. Experimental results are compared against simulation based on retinal scattering model.