From the anatomical point of view, the most important tests are those used for visual fields, since they may indicate chiasmal compression (for example, resulting from a pituitary tumour). For early diagnosis of such lesions, peripheral vision is assessed using a red pin, where patients inform the doctor when the colour red appears in their outer field of view (Fig. 2.18). Red-colour perception is lost before perception of other colours or white light. Additionally, visual fields should be plotted objectively: for example, by using the Goldmann perimeter. Typical Goldmann plots showing bitemporal field defects are illustrated in Fig. 2.18.
