Mac Degen in 2010 – Page 24 of 62

When a dot-deviation signal is projected on a healthy retina, it stimulates a collinear set of retinal receptive fields. Special neuronal circuits in the visual cortex process this information, leading to the perception of a straight dot-deviation signal (Figure 1). When photoreceptors are displaced, both in the case of when drusen are present as in intermediate AMD, and often to a more significant degree when CNV develops, a geometric shift in photoreceptor location might occur. Therefore, linear signals may be perceived as distorted or misaligned (Figure 2).