Overview image
The overview image is generally one that is used to set the scene. In normal practice several images may be required to record faithfully the state of the eye and a simple, low magnification image can be used to orientate the viewers of an image series.
The diffuse illumination is achieved by fitting a diffuser to the slit illuminator and opening the slit to the widest beam. This can be used in combination with the background illuminator to produce an image that has balance and shows good detail. If the sole illuminator is used close to the optical axis the image may lack detail as in this position the lighting will flatten some features in the subject. If the angle between the illumination and slit-lamp objective is increased to around 45 degrees, detail will be enhanced; however, one side of the image will appear dark. Using a second source at 90 degrees to the primary light source will reduce this effect and improve the image (Figures 2a and b).
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