Figure 1

Aperture plate from Zeiss SL 105 slit lamp showing crescent-shaped and circular apertures. The red arrow points to the 3.5 mm circular aperture (which is projected onto the fundus in Figure 3). If this plate is rotated in an intermediate position, with the aid of the second aperture for the width of the slit beam (see yellow rectangle) two halfcircles visible in Figure 5 can be projected onto the fundus.