Low-Cost Device for Digital Retinal Imaging

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DESCRIPTION (provided by applicant): The goal of this research is to provide a low cost device for digital retinal imaging, the Laser Scanning Digital Camera, as an integral part of screening for diabetic retinopathy. This device will be unusually inexpensive and provide images with contrasts at least as high as those now used clinically. It will eventually provide the ease of use of a digital camera, minimizing current problems with training. This new technique will provide a long-awaited tool to basic researchers and clinicians alike for detecting diabetic retinopathy early, in an inexpensive and sensitive manner. Unlike recent devices with more than 30 % failure rate in the field, we anticipate use with every patient without severe corneal problems or severe cataracts. The Laser Scanning Digital Camera uses our unique hybrid system of slit-scanning the illumination, and detection by a 2- dimensional array with electronic aperture, using primarily low cost, off-the shelf components. We perform confocal imaging using a newly-demonstrated electronic aperture, which reduces scattered light from out-of-plane structures and thereby improves image contrast. We will test the flexibility of the electronic aperture to provide scattered light, i.e. dark field, imaging, as well as image averaging and image sharpening. The camera works with an undilated pupil, due to the small entrance/exit split pupil system and near infra-red light. All clinically important retinal vascular changes and macular edema have now been visualized by us with higher end devices, including microaneurysms and features in darkly pigmented eyes. Stereo imaging was recently shown to be unnecessary for detecting macular edema, and therefore we will provide high contrast images to obtain cues for judging macular edema. We will implement our technique from high end devices: scattered light imaging. Aim 1 is to complete the development of the Laser Scanning Digital Camera, including new imaging modes provided by the electronic aperture. Aim 2 will begin field work, with reproducibility studies and eye pigmentation comparisons in normal subjects and initial tests in patients with moderate nonproliferative diabetic retinopathy. We will use the electronic configuration to optimize the optical confocal aperture width. Aim 3 investigates confocal near infra-red imaging techniques, including real-time variation of aperture, image sharpening, and scattered light imaging, as applied to a population with the full range of retinal changes found in patients with diabetes. We anticipate enhanced detection capability for edematous lesions, e.g. cystoid macular edema. Aim 4 is to achieve motionless confocal scanning laser imaging, but still retain the movable part needed for focus, and compare this method to that used in Aim 3. We will also include an anterior segment imaging component, which is extremely inexpensive, as diabetic patients with dark eyes can have new vessel growth in the iris that leads to painful and sight-threatening glaucoma. This will also document eye color and provide help with quality control by giving the pupil diameter. While this project focuses on diabetic retinopathy in humans, future applications include other retinal disorders in both humans and animal models.