Visual Consequences for Children with Early Acquired Lesions to the Optic Radiation—Vision ‘without Seeing’

Abstract

The brain lesion caused by perinatal hypoxic-ischemic events at gestational age 24 – 34 weeks has a typical anatomical pattern known as periventricular leukomalacia (PVL). PVL affects the corticospinal tracts, causing spastic diplegia and/or the geniculocalcarine tract, causing visual impairment. Computer tomography or magnetic resonance imaging are the methods of choice for diagnosing PVL. This lesion is the cause of visual impairment in 20% of all visually impaired children in a Swedish population of children born in 1989 – 1995.

The visual deficit in PVL is characterised by decreased vision with crowding (an inability to resolve linear optotypes, while single optotypes of the same size may be identified) and visual field defects, further complicated by perceptual and cognitive problems. A relatively high single optotype acuity may lead to overestimation of visual function. Oculomotor impairments with strabismus and nystagmus are common findings. Colour vision is often preserved and used by the children as one of many strategies to sort out an otherwise chaotic visual world. Instead of looking, these children listen carefully, talk a lot and remember well, and sometimes use tactile information to solve visual tasks. They easily get lost in new surroundings and they recognise known faces among others only by the voice and the colour of the clothes. Reading is often difficult. This group of visually impaired children call for adaptation of education and habilitation to manage daily life, mobility, and reading.