Colour imaging using a scanning laser ophthalmoscope

New imaging techniques have opened up new possibilities for visualising the living human eye and can provide quantitative measurements of fundus features. One of the most important developments has been based on the scanning laser ophthalmoscope (SLO) which has the property of providing optical sections through the use of confocal optics.1 2 This can reveal three dimensional aspects of structures which would otherwise be invisible owing to the contrast degrading effects of overlying elements. The confocal SLO has had a major impact on research in ophthalmology and continues to break new ground in advancing the limits of seeing and measuring properties of the eye. The first widely used SLO was the Rodenstock device which provided facilities for confocal imaging, fluorescein and indocyanine green angiography, and psychophysical measurements such as microperimetry. These used a variety of lasers of different wavelengths to give real time video images. In comparison with photographic techniques, the spatial resolution of video images is inherently lower. This is because the horizontal scan lines which make up the image are limited to approximately 600 compared with the equivalent of 4000 or more for photographs. The mechanical limitations of the spinning …