Introduction
This activity simulates what it is like to have a scotoma in the user’s central vision due to age-related macular degeneration (AMD). First, let’s break down the components of AMD and think about what each part of the term means. The “age-related” part of the name indicates that this disease usually occurs in older adults, starting around age 50 and becoming more prevalent with age. The “macular” in AMD refers to the central part of your retina, the macula, that contains the fovea and a high concentration of cones. It is this part of the eye that is specifically affected by AMD, leading to a loss of central vision. The “degeneration” part of AMD can occur in either a “wet” or “dry” form. The wet form causes vision loss due to abnormal blood vessel growth (and possible leakage) below the macula, while the dry form causes vision loss via atrophy of the pigment epithelial layer below the retina, leading to degeneration of the rods and cones above it.
Once photoreceptors die off in the fovea, it is impossible to regrow them. This results in a loss of central vision–a blank spot in the visual field–called a scotoma.
In this activity, the user experiences a bit of what it is like to have a central field scotoma. In the center of the circle on the left is a large black region that blocks the view of the photograph of a US president behind it. The user keeps their eyes fixated on the white + in the center of the black mass, and moves the circle around and try to guess which president is being pictured behind. If the user keeps focusing on the white + sign, then the black mass fills their central vision, making it difficult to see the image behind. People typically want to peak at the edge of the circle where the scotoma is absent to get a better view of the president, which makes them realize how important their central vision is! AMD results in central vision loss and this activity helps the user realize how important their central vision is to everyday activities like face recognition.