At this point the cornea has been examined with diffuse white light and for fluorescein staining. An illumination system called sclerotic scatter is useful in detecting central corneal clouding (corneal edema) created with rigid lenses and other corneal opacities such as scars, foreign bodies and abrasions.
A light beam of 2 to 4 mm wide is placed on the temporal limbus (#1). The light source should be rotated such that it is off to the side of view (microscope focused on the center of the cornea and light source on the limbus). When properly set up the limbus 180 degrees from the light beam will glow (#2).
