The scanning laser ophthalmoscope.

The imaging of the fundus of the eye poses two major technical challenges. First, it is necessary for both the illuminating and reflected beams to pass through the same aperture, the iris. In some commonly used instruments this leads to the use of levels of illumination close to the maximum tolerable by a patient. Second, in order to visualize the different structures present in the various layers of the fundus it is necessary to perform tomographic imaging. The scanning laser ophthalmoscope provides an answer to these particular problems. By scanning the fundus with a narrow laser beam most of the area of the iris is then available for the reflected light and so the intensity of the illuminating beam can be kept low, making it more acceptable for patients. The use of confocal imaging allows 3D images to be produced. In this short review the performance of the instrument will be discussed and its application to a number of clinical problems in ophthalmology considered. Finally there will be a brief description of other instrumentation currently under development.