Refractive errors and automated perimetry: discussion and case studies.

1. The effects of refractive error on automated perimetry were studied. The results of the study showed that an error of as little as 1 diopter can significantly influence the visual field to as much as 30 degrees from fixation. 2. In the case of automated visual field testing when only the central 30 degrees of visual field are tested, refractive error can cause a generalized depression. Because generalized depression can have several different causes, distinguishing between a true depression and one due to refractive error can be important. 3. Because a generalized depression from refractive error can mimic a depression due to true pathology, it is critical that the most recent refraction combined with the correct add for perimetry be used on each patient every time the patient undergoes a visual field examination.