The assessment of vision in the preschool child.

The developmental, optometric, and practical issues that govern clinical examination of vision from birth to 5 years and their bearing upon diagnostic and surveillance practice is discussed. Our current understanding is that minor defects of the visual system do not significantly constrain general developmental progress or early visual development while severe visual impairment can seriously impede both.' 3 Both benefit from skilled developmental management.34 The earlier surgical and optical treatment are implemented for the few conditions amenable to this approach such as cataract, retinoblastoma, and glaucoma, the greater the benefits in terms of vision, general development, and health. At least two thirds of babies with severe visual impairment require paediatric management including genetic counselling; the effectiveness of this is improved by early diagnosis.