Bernard Morin developed glaucoma at an early age and was blind by the time he was six years old. Despite his inability to see, Morin went on to become a master topologist—a mathematician who studies the intrinsic properties of geometric forms in space—and earned renown for his visualization of an inside-out sphere.

For sighted people, it can be difficult to imagine learning math, let alone mastering it, without vision (or even with it). In grade schools, mathematics instruction tends to rely heavily on visual aids—our fingers, pieces of pie, and equations scribbled on paper. Psychology and neuroscience support the notion that math and sight are tightly intertwined. Studies show that mathematical abilities in children are highly correlated with their visuospatial capacities—measured by proficiency in copying simple designs, solving picture puzzles, and other tasks—and that brain areas involved in visual processes are also activated during mental mathematics. Researchers have even proposed a “visual sense of number,” the idea that the visual system in our brain is capable of numerical estimation.