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Real-time single-pixel camera ophthalmoscope


Purpose : The examination of the retina is crucial for early detection of any unwanted alteration. Although there are different successful implementations of retinal imaging devices (ophthalmoscopes), new robust systems able to operate under many eye’s conditions may have a practical importance. Here, we introduce, as a proof of concept, a novel approach to image the retina in real time using a single-pixel camera.

Methods : The Single-Pixel camera Ophthalmoscope (SPCO) is based on the concept of sequentially detecting the inner–product’s intensity of the object and a series of controlled base patterns. The image corresponding to the object is subsequently reconstructed computationally. The used configuration was a double-pass system that contains a digital micromirror device (DMD) creating a spatially coded illumination that were projected on the retina covering a field of around 16 degrees. The DMD was able to display series of Hadamard patterns with a rate up to 22 kHz. For each projected pattern, the reflected light coming from the retina is detected with an avalanche photomultiplier (single-point detector). After displaying a distinct number of patterns, an image of the retina is retrieved and displayed within our developed software interface in real-time.

Results : Experimental results obtained using an artificial eye confirmed the viability of this approach. We were able to reconstruct images with a resolution up to 128 x 128 pixels. Furthermore, real-time video streaming with a frame-rate between 1 to 20 frames per second depending on the chosen resolution was produced. The use of sub-sampling techniques based in the spatial content of the images could either increase the frame rate or the image size. Since multiplexed illumination may offer a SNR improvement when compared to traditional approaches, this may reduce the light illuminating the eye.

Conclusions : A novel approach to obtain images of the retina based in a single point detector has been proposed. The instrument (SPCO) operates in real-time and should be extremely tolerant to a variety of ocular conditions that typically degrade the images of the fundus, including large refractive errors or opacities.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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