The object of the study are 126 children with internal hydrocephalus treated within the period 1978-1990. The children were preoperatively divided into six groups according to the etiology of the hydrocephalus. Disorders of the visual functions accompanying elevated intracranial pressure (setting sun 51, syndrome of the aqueduct of Sylvius 14, paresis of craniocerebral nerves 9, nystagmus 8, optic atrophy 4) were established preoperatively in 48.4% of the children. 44 of the children were revised because of malfunction of the shunt with the following neuroophthalmological symptoms: setting sun 6, paresis of craniocerebral nerves 9, syndrome of the Sylvius aqueduct 6, papilledema 6, optic atrophy 9 and nystagmus 5. The fact that a great many changes in the visual functions sometimes precede the manifestations of the changes in CT image determines their significance for early diagnosis and treatment.