A comparison of four projection perimeters.

Identical specifications for size and luminance of the target and dome on four projection perimeters-Goldmann, Marco, Topcon, and Rodenstock- seemed to indicate that similar visual fields should be plottable with each instrument. We subjected 30 eyes to perimetry with all four machines. The Rodenstock perimeter was usually unable to map the central field with the I2e target and to identify the presence of most visual field defects. The Goldmann was most capable of demonstrating the presence of existing scotomata and was also able to plot them with the greatest definition. The Topcon was next most sensitive followed closely by the Marco. Analysis of the actual target size and luminance on each machine showed that significant variation existed and was probably responsible for the visual field differences that we found.