Figure 5  .

Schematic representation of the parallel line test evaluating the completion phenomenon in subjects with a paracentral scotoma. It shows the relative positions of the fixation point (cross), vertical test lines, and right paracentral scotoma (shaded area). The vertical lines are equal in length and are equidistant from the fixation point. They are presented to the subject in such a way that the line located on the affected side of the visual field crosses the scotoma, and extends for a short distance on either side of it. After steadily fixating the cross for 5-10 seconds, the subject is asked about any perceived interruption in the lines or inequality in their length, and is asked to indicate, on the line located on the unaffected side, the levels corresponding to the perceived upper and lower ends of line on the affected side (as exemplified by the two arrows).