Low Vision Rehabilitation Intervention for People with Ring Scotomas

Central scotomas--areas of the nonseeing retina within the central 20 degrees of the visual field--are present in approximately 90% of vision rehabilitation patients. They vary in size and shape and can be small or large, symmetrical or asymmetrical, round or irregularly shaped. Most central scotomas border fixation on one side and can be overcome with magnification and sometimes eccentric viewing. However, these strategies seldom suffice in the case of ring scotomas, which border three or four sides of fixation and have been present in 20%-47.5% of patients with eye conditions that affect central vision. Patients with ring scotomas generally have near-normal acuity, which does not reflect their functional impairment in reading and activities of daily living. They display a characteristic slow-fast-slow reading pattern when performing tests such as the MNREAD acuity chart. They read the largest print slowly, speed up with the middle print sizes as more letters fit within the central island of vision, and then slow again when the print drops below the size they can discern. Most patients with ring scotomas fixate centrally even for targets that are larger than the central island, possibly because reorganization of cortical visual processing only occurs in the absence of foveal vision. This article discusses the three principles that characterize the approach to intervention for patients with foveal-sparing scotomas: (1) education about the scotoma; (2) supporting the use of the limited central vision; and (3) maximizing the potential to use the peripheral retina. (Contains 1 figure.)