Evaluation of the apparently blind child

Abstract

Inevitably, an ophthalmologist who cares for children will be challenged by an infant with apparently poor vision. In most cases, the causes can be divided into three categories. The first category is comprised of infants in whom the abnormality is apparent after thorough ocular examination. Anterior segment abnormalities may suggest microphthalmus, aniridia, albinism, cataract, or glaucoma. An abnormal fundus examination could reveal optic nerve abnormalities, abnormal vitreous or retinal pathology suggestive of Leber's congenital amaurosis, achromatopsia, or congenital stationary night blindness [6, 42]. The second category consists of those infants with subtle or non-existent retinal findings but abnormal ERG. The third category of infants present with the suspicion of blindness and a normal ocular examination. These children are particularly challenging. They are a challenge diagnostically due to frequently associated developmental or neurological deficits [26]. They are a challenge emotionally for parent and physician because the diagnosis to be given varies widely prognostically from a sighted life to one of severe visual impairment. Caution should be used in labeling a child as blind because the definitions vary between organizations, academic and educational fields, and the public. The World Health Organization (WHO) defines blindness as a corrected visual acuity in the better eye of < 3/60 (20/400) and severe visual impairment as a corrected acuity in the better eye of < 6/60 (20/200) [15, 16]. Both of these acuity levels are far better than complete loss of sight, which can be inferred by the term "blindness." The WHO epidemiology studies of childhood blindness underscore the discrepancy between causes of visual impairment in regions with higher versus lower socioeconomic status. Westernized countries have significantly higher numbers of nonocular, central nervous system (CNS)-related causes of blindness, a difference which has been attributed both to improved treatment of ocular disease and to perinatal intervention resulting in an increased survival rate of low-birth-weight and premature infants. This change in epidemiology brought cortical visual impairment (CVI), vision loss due to bilateral CNS damage, to the top of the list of childhood causes of blindness in the United States; however, CVI must be distinguished from other forms of visual impairment with normal ocular examinations such as congenital motor apraxia and delayed visual maturation. This chapter focuses first on history and examination of the child who presents with suspicion of blindness. The more common entities of non-ocular visual impairment are then discussed including congenital ocular motor apraxia, CVI, and delayed visual maturation with attention to particular aspects of clinical presentation and assessment in each condition. © 2009 Springer Berlin Heidelberg.