APPARATUS AND METHOD FOR TOPOGRAPHICAL ANALYSIS OF THE RETINA

A novel optical subsystem is connected to an analyzing computer. The optical subsystem projects a grid of parallel lines onto a patient's retina, and a video camera in the optical subsystem captures a first retinal image and transmits it to the computer, where the image is digitized for analysis. A second image of the same eye is also captured, with the grid of parallel lines oriented perpendicular to the grid of the first image. The computer stores image data for the patient for a plurality of visits. The computer analyzes the images by forming a skeletonized topographical map of the retinal area of interest. First, a novel one-dimensional line detection algorithm is used to process the images. The line detection algorithm dilates, erodes and restores, Fourier transforms, bandpass filters, thresholds, skeletonizes, line traverses and interpolates the data for each of the two images. The resulting information is normalized to compensate for the effects of the patient's ocular optics. A topographic line map is constructed using the lines detected in the two images and the map is divided into sections for analysis. Using selected landmarks, the computer then registers the map with the topographic maps constructed from images acquired on previous patient visits. Volumetric changes in the topography of the retina as compared to the prior topographies for the patient are calculated, and, with other quantities of interest, are displayed in an easily-interpreted report.