Real-time retinal tracking for laser treatment planning and administration

We propose a computerized system to accurately point laser to the diseased areas within the retina based on predetermined treatment planning. The proposed system consists of a fundus camera using red-free illumination mode interfaced to a computer that allows real-time capturing of video input. The first image acquired is used as the reference image for treatment planning. A new segmentation technique was developed to accurately discern the image features using deformable models. A grid of seed contours over the whole image is initiated and allowed to deform by splitting and/or merging according to preset criteria until the whole vessel tree is extracted. This procedure extracts the whole area of small vessels but only the boundaries of the large vessels. Correlating the image with a one-dimensional Gaussian filter in two perpendicular directions is used to extract the core areas of such vessels. Faster segmentation can be obtained for subsequent images by automatic registration to compensate for eye movement and saccades. Comparing the two sets of landmark points using a least-squares error provide an optimal transformation between the two point sets. This allows for real-time location determination and tracking of treatment positions.