Retinitis pigmentosa

At first it is only the twilight. You notice that in half-darkness it takes longer for your eyes to adjust. In the evening on the street, faces seem wiped away. In a dimly lit room you stumble over things others recognise effortlessly. Later the peripheral vision follows — what is happening to the side begins to withdraw. An object standing immediately next to you disappears from your field of vision. Your seeing contracts, from outside to inside, year by year. In medicine this process is called retinitis pigmentosa: a hereditary, progressive degeneration of the retina in which the light-sensitive cells lose their function — first the rods, which work in the periphery and in darkness, later also the central cones.