Scanning laser ophthalmoscopy. Its value in macular diseases

The scanning laser ophthalmoscope provided a high quality television image of the fundus with minimal illumination of the retina. This new device based on a totally new electro-optical principle allowed a detailed exploration of macular function directly under simultaneous fundus control. The focused beam of a yellow krypton laser (568,2 nm) was swept up and down, rights and links across the fundus to form a raster of parallel lines on the retina. The S.L.O. illuminated only a single retinal point at a time and illumination was reduced to less than 70 microw/cm2 versus 100,000 microns/cm2 for indirect ophthalmoscopy and 4,000,000 microw/cm2 for fluorescein angiography. The intensity of the laser beam could be modified with the microcomputer by means of an acousto-optic modulator. It was possible to produce static or dynamic graphic designs that were simultaneously viewed by the patient and observed by the examiner on the patient's fundus on the video monitor. Further computerized analysis of the videotaped scanning laser ophthalmoscopic images gave a functional retinal map with correction for shifts of stimulus position due to fixational saccadic eye movements. The map showed true retinal location of 1. fixation area; 2. scotoma. The clinical evaluation was completed with 3. measurement of visual acuity in any foveal or parafoveal location. The results of scanning laser ophthalmoscopy were illustrated with the report of datas in a patient with diffuse retinal pigment epithelial decompensation.