The history of research into the disorders of reading and accommodation in strabismic amblyopia

Abstract

During the past 150 years, research on amblyopia and nystagmus has developed in five different waves (W1–W5). Amblyopia was initially regarded to be enigmatic and believed to be related to eccentric fixation (W1, after 1850); later, it was ascribed to disorders in refraction or accommodation (W2, around 1900). After 1900 (W3), phylogenetic explanations appeared, and after 1945 (W4) concepts based on successful orthoptic practice came to the fore. Since 1965 (W5), research on amblyopia has been guided by modern insights into neuroanatomy and neurophysiology. In contrast to amblyopia, nystagmus has always been a well-defined symptomatic entity. Even though amblyopia and nystagmus are both symptoms of strabismus, their understanding has therefore developed along different paths. In juvenile strabismus, defects in binocularity lead to monolateral amblyopia, while defects in contour vision lead to bilateral nystagmus. In the present paper, these five waves of amblyopia research are described in more detail, with particular attention to the concepts of adaptation, visual fields, and sensory and motor functions as related to disorders in reading and accommodation.