Digital image processing of fundus images using scanning laser ophthalmoscopic images

摘要

Abstract: Many ocular diseases of the human fundus could be quantified from the visible pathological features. Fundus images are usually recorded on a photographic film using a fundus camera that employs very high levels of illumination. Scanning laser ophthalmoscopy is a new method of imaging the fundus that offers the unique capability of differentiating various pathological conditions using very low light levels and has the confocal capability to collect light from different layers. The scanning laser ophthalmoscope (SLO) uses a narrow beam of laser to illuminate the fundus. Only a single point is illuminated at a time and the fundus is scanned in a raster pattern and the reflected light is detected y a photodiode. Patients with pathological conditions such as cataract, exudates, macular and optic disc drusen were imaged using lasers ranging from 488 nm to 830 nm. Images were analyzed using Visilog image processing software on a SUN IPX Sparc station. Image processing to quantify the area of exudates macular drusen and optic disc drusen showed better accuracy when compared to registered digitized fundus photographs. Quantitative analysis of contrast of retinal vessels in fundus images of cataract patients demonstrated significantly higher contrast for the SLO at all wavelengths tested. Development of a color SLO using multiple lasers and tomographic imaging suing very small confocal apertures are in progress and preliminary results will be presented. !21