Background: Digital imaging systems provide immediate, magnified images that can easily be analysed, enhanced, archived, printed on near photographic-quality paper and transferred electronically to remote computers. We have assembled a digital ophthalmic system and tested it on patients with some common causes of blindness: corneal scarring and cataract, diabetic retinopathy, macular degeneration and glaucoma.
Methods: Digital images were obtained using a variety of ophthalmic imaging devices ranging from slit-lamp, fundus camera, indirect ophthalmoscope and scanning laser ophthalmoscope. These images were compressed in order to concentrate image information (image size reduced by 90-95%) and minimize transmission time (reduced by 97-98%). Standard or mobile telephone lines were used to transmit images to remote terminals.
Results/discussion: Transmission time was reduced from 15-20min to 20-30s and the image size was reduced from 1.3 MB to 20-30 kB by compressing the images before transmission. Image quality is still excellent.