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Disorders of visual perception are frequent and disabling functional consequences of acquired brain injury (20-40%). They also have adverse effects on the assessment, diagnosis and treatment of other functional disorders. Most frequent are visual field disorders followed by disorders of visual acuity and contrast sensitivity, visual adaptation, color and visual space perception as well as of visual recognition. Multiple visual and/or additional cognitive disorders are most common. The differential diagnosis of cerebral visual disorders and an individually tailored and specific approach in the rehabilitation are therefore of great importance. Compensatory treatment methods are to be preferred because of their efficacy, ecological validity as well as a good cost-benefit ratio.

Human neuropsychology is the study of brain-behavior relationships based on the analysis of functional disturbances after brain damage. The assessment and analysis of pathological states and processes in the brain on cognition, speech and language, praxis, motivation and affectivity, represent the main topics of neuropsychological research. Patients with psychiatric disorders very often exhibit cognitive impairments which should also be assessed by means of specific neuropsychological diagnostic tools. The advantage of such tools is their validity and reliability which allow accurate qualitative and quantitative analysis and characterization of the various cognitive impairments. Neuropsychological methods of assessment can also be used for follow-up measurements, for example, in studies on the effect of medication. Finally, the outcome of a comprehensive neuropsychological assessment can provide a useful basis for the treatment of cognitive impairments in psychiatric patients using means that have proved successful in brain-damaged patients.

A questionnaire for the subjective assessment of cerebral visual disorders was administered to 269 brain damaged patients. The patients' subjective complaints were correlated with the outcome of objective diagnostic procedures (visual perimetry, visual search, spatial contrast sensitivity, visual evoked potentials, depth perception, light- and dark-adaptation, reading, colour vision). A significant correlation was found between subjective complaints and objective diagnostic results for all fields. The prediction of visual impairments on the basis of subjective complaints and verified by objective tests was correct in 80 to 98% of the brain damaged patients tested. Interrater reliability was about 0.84. Thus, the questionnaire is suitable for the assessment of cerebral visual disorders because of its simplicity, short administration time (10-15 min) and high predictive value.

Electrooculographic (EOG) records were studied in 10 neurological patients with disturbances of activation according to clinical assessment and in 12 normal subjects. Rapid horizontal eye movements (saccades) and movements of the eyelids (blinks) were measured. It was concluded that the frequency distribution of blinks and saccades indicates activation deficits in a sensitive and reliable way. The continuous decrease of activation from orthological to pathological states could be shown by counting the frequencies of blinks and saccades. The relationship between the two variables is interpreted with regard to its functional significance.

The term "neglect" designates various kinds of failure to orient or respond to or to report stimuli appearing at the side contralateral to a cerebral lesion. This failure cannot be explained by primary sensory or motor disorders. Essentially the following symptoms of neglect have been reported: inattention to visual (or) acoustical stimuli in one hemifield under unilateral and simultaneous bilateral presentation reduction in orienting responses (eye and head movements) to the neglected hemispace and deviation of head and gaze axes towards the intact hemispace omission or incomplete reproduction of one side of a figure of a text when copying or drawing from memory omission of one half of a well-known scene or picture when reporting from memory deviation of the egocentre as tested by visual, acoustic and somatesthetic stimuli towards the intact hemispace reduction of motor activities, especially for the extremities of one half of the body, which cannot be attributed to a sensory motor deficit inattention to somatesthetic stimuli presented on one side of the body displacement of somatesthetic stimuli, presented on the affected body side, to the intact body side lack of "awareness" of the existence of one half of the body, resulting in, e.g., ignoring this body half when washing or dressing "reference" of the neglected body half to another person unawareness or denial of severe sensorimotor deficits (e.g. hemiparesis) in the affected body half. The syndrome of neglect should be carefully differentiated from inattention phenomena resulting from primary sensory (e.g. hemianopia, restriction of field of search) and motor deficits (hemiparesis, hemiakinesis). In some cases this differentiation is rather difficult, because both types of inattention may be combined. Thus, detailed testing of sensory and motor disorders is needed in order to avoid any precipitate diagnosis of "neglect". The neuropathology of the neglect syndrome is not yet known precisely. Damage to the parietal lobe (presumably of the nondominant hemisphere) is the most common cause for neglect. Lesions at the bank of the sulcus intraparietalis seem especially crucial. Lesions in the dorsolateral frontal lobe causing neglect are mainly situated in Brodmann's premotor areas 8, 9 and 46. Furthermore, lesions of the anterior cingular cortex (area 24), of the thalamus (intralaminar nuclei, nucleus ventralis lateralis, pulvinar) and of the basal ganglia seem to induce neglect.

On the basis of a clinical and electrooculographic observation the phenomenon of periodic alternating eye deviation is discussed. The few cases in the literature are reviewed and the topography of the lesions causing eye deviation is considered.

The majority of patients with homonymous visual field disorders after postchiasmatic brain damage suffer from reading disabilities (known as hemianopic dyslexia) because the residual visual field is too small for complete comprehension of words and sentences. Furthermore, they typically show a reduction of searching movements in the affected hemifield. As a rule, an adequate adaptation of their reading and searching strategies to the field disorder does not take place spontaneously. Therefore, these patients need early and efficient systematic treatment. Using a new electronic device, both the impairments in reading and in visual exploration can be treated successfully within a relatively short period of time. Most of the patients successfully employ the strategies learned during training in their everyday lives. Thus, the proposed treatment may be considered an effective means of reducing the degree of their visual disability.