When an infant has not developed good visual attention or the ability to fixate on and follow objects by 3–4 months of age, the clinician must determine whether the decreased vision is due to an ocular or optic nerve (pregeniculate) condition, cerebral (retrogeniculate) visual impairment, or delayed visual maturation. This chapter discusses the classification of visual impairment in infants and children, as well as the evaluation and rehabilitation of these patients.
Visual Development in Young Infants
Visual development is a highly complex maturational process. Structural changes occur in both the eye and the central nervous system. Laboratory and clinical research has shown that normal vision develops as a result of both genetically programmed neural development and normal early visual experience.
A blink reflex to bright light should be present within a few days of birth. The pupillary light reflex is usually present after 31 weeks’ gestation but can be difficult to evaluate in the early neonatal period because the newborn’s pupils are miotic.
At approximately 6–8 weeks of age, the healthy full-term infant should be able to make and maintain eye contact with other humans and react with facial expressions. Infants aged 2–3 months should be interested in bright objects. By age 3–4 months, the nasal bias for smooth pursuit should have resolved, the eyes should be orthotropic, and fix-and-follow responses to a small (2–4 inches in diameter) toy should be present. Premature infants can be expected to reach these landmarks later, but there is not an exact week-for-week correlation for the attainment of these milestones.
Dysconjugate eye movements, skew deviation, and sunsetting (tonic downward deviation of both eyes) may be noted in healthy newborns but should not persist beyond approximately 3–4 months of age. Signs of poor visual development include searching eye movements, lack of response to familiar faces and objects, and nystagmus. Staring at bright lights and forceful rubbing or poking of the eyes (oculodigital reflex) in an otherwise visually disinterested infant are other signs of poor vision and suggest an ocular cause for the deficiency.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.