When it comes to interpreting visual fields, one of the more subtle aspects of visual fields is distinguishing between absolute scotomas and relative scotomas. On the surface, this may seem fairly simple; on a grayscale readout, absolute scotomas tend to be completely black, while relative scotomas are varying shades of lighter gray. However, some relative scotomas can still look fairly dense.
Introduction to Perimetry
What Is Perimetry?
Perimetry, the measuring and documentation of the visual fields, has a long and exhaustive history (Thompson HS, Wall M. History of Perimetry. Imaging and Perimetry Society website). There are many methods of testing perimetry, which have evolved with technology and greater understanding of neuroanatomy and functional vision.