Does my nearsightedness come into play when creating light outlines in the distance?
Not likely.  The afterimage you see when you close your eyes is an effect dependent upon which light-receiving cells in the retina (rods and cones) saw light when your eyes were open.  The blurry image you saw when your eyes were open has the same size and shape as the afterimage you see when you see when you close your eyes.  Because the afterimage has less detail, perhaps you would be less distracted by detail and be able to pay more attention to shape, but it seems unlikely that would noticeably help your idea of the shape.