Background-Optic nerve head drusen may present diagnostic diYculties in cases of disc swelling. Imaging of the nerve in a search for drusen is often inconclusive, especially in children, where drusen may be buried below the surface of the nerve head. Methods-A small study was carried out using a scanning laser ophthalmoscope (SLO) with an infrared confocal facility to scan deep within optic discs in an attempt to image drusen. Results-The SLO was able to demonstrate superficial and buried drusen (using the infrared confocal facility). The superiority of the SLO over ultrasound in the presence of lens opacity was revealed, as the SLO simultaneously demonstrated both drusen and the associated anomalous disc features which are not detected by ultrasound. Conclusion-The SLO can help in the diagnosis of optic disc drusen especially in diYcult cases where lens opacity or buried drusen hinders their definitive diagnosis. (Br J Ophthalmol 1997;81:654-657) Imaging of optic nerve head drusen has been attempted by several diVerent techniques, with varying degrees of success. Recent work has shown that fluorescein angiography may show autofluorescence and late staining of disc drusen in some cases; that computed tomography (CT) and magnetic resonance imaging (MRI) inconsistently show superficial calcification or lucency respectively; and that only B-mode ultrasonography consistently demonstrates calcified optic disc drusen.1 However, few of the associated diagnostic features of discs with drusen are demonstrated by ultrasound and in the presence of opacity of the media, doubt over the possibility of dual pathology will persist. In this brief report, we demonstrate the value of the scanning laser ophthalmoscope (SLO) in demonstrating optic disc drusen and the associated disc abnormalities, even in the presence of lens opacity. Materials and methodsSLO imaging of 12 eyes with optic nerve head swelling was carried out using a custom built device. The construction and performance characteristics of this instrument are detailed elsewhere.2 3 Briefly, the SLO uses a highly collimated narrow beam of laser light to sweep over the retina, delivering all its energy to a very small spot for a very short time. Light returning from that spot is detected and synchronously decoded to form an image on a monitor. The SLO has 'confocal optics', meaning that detection of returning light takes place at a focal point which is conjugate to the focus of the illumination spot on the retina. This is achieved by the use of a confocal aperture which allows only light which is brought to a focal point at the aperture to pass through the aperture and thus to the detector. Any light brought to focus in front of, or behind the aperture (that is, light arising from a focal plane deep to, or superficial to the confocal point) will not pass through the aperture and will not be detected. Therefore, the SLO allows analysis of light from a particular depth of the illuminated fundus. The slice thickness analysed is dependent on the size of the confoc...

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