Diseases such as age-related macular degeneration, cone-rod dystrophy and Stargardt disease cause scotomas, or blind spots, which often have devastating effects on central vision. They cause gaps in a person’s visual field, making it difficult to see words in a book, images on a computer monitor or TV and the features of someone’s face.
A recent research paper from Lighthouse International and the New York University School of Medicine focuses on these fixation problems.
The investigators noted that people with normal vision use their fovea — a pit in the center of the retina that is rich in cones — as the focal point for fixation. If the fovea is compromised by retinal disease, a person may develop “pseudofoveas” in the peripheral areas of their retinas. They are the brain’s and retina’s way of trying to compensate for the lost focal point. However, pseudofoveas can’t fixate as well as the natural fovea.
While some retinal conditions such as retinitis pigmentosa affect the peripheral retina first, they, too, can cause fixation problems in advanced stages, when the central retina becomes affected.