delayed developmental milestones.

Comprehensive ophthalmologic examination of the infant should begin with an assessment of visual behavior. Vision in the infant is usually assessed qualitatively by clinical appraisal and observation of optokinetic nystagmus (OKN) responses, as well as quantitatively by psychophysical tests such as visually evoked potential or response (VEP or VER) and by preferential looking tests such as Teller Acuity Cards II and the Cardiff Acuity Test (see Chapter 1). Pupillary light responses, ocular alignment and motility, presence or absence of nystagmus or roving eye movements, anterior segment and fundus examinations, and cycloplegic refraction are the other important parts of the evaluation.

Pupillary responses are sluggish with anterior visual pathway disease such as retinal dystrophies and optic nerve abnormalities. Paradoxical pupils (pupillary constriction in response to darkness) are most commonly associated with retinal dystrophies, but they can also occur with optic neuropathies. Pupillary responses are normal in infants with cerebral visual impairment (see the section Retrogeniculate Visual Impairment, or Cerebral Visual Impairment). Nystagmus may be an indicator of bilateral pregeniculate visual dysfunction (see the section Pregeniculate Visual Impairment), or it may be purely a motor anomaly. The nystagmus usually starts at 2–3 months of age (see Chapter 13). Visual deficits in 1 or both eyes frequently cause abnormal ocular alignment (either esotropia or exotropia; see Chapters 8 and 9, respectively).

Classification of Visual Impairment in Infants and Children

When an infant or child presents with poor vision, the workup is predicated on localizing the visual dysfunction. It is helpful to classify disorders causing visual impairment in infants as delayed visual maturation or pregeniculate or retrogeniculate visual dysfunction (cerebral visual impairment). Although this is a useful clinical paradigm, it should be recognized that some disorders affect both the pregeniculate and retrogeniculate pathways.

Delayed Visual Maturation

Normal visual fixation and tracking usually develop in infants within the first 3 months of life. If this does not occur, the condition is referred to as delayed visual maturation (DVM), or cortical inattention. Ophthalmologic and systemic examination of infants with DVM usually reveals a cause. There are 3 subgroups of infants with DVM: otherwise healthy infants, infants with systemic/neurologic abnormalities, and infants with structural eye anomalies.

In an otherwise healthy infant with DVM, the following findings suggest a good visual and neurologic prognosis: some reaction to light, normal pupillary responses, no nystagmus, and normal ocular structures. If the visual behavior does not progress toward normal by 4–6 months of age, further investigation (neuroimaging or electrophysiologic testing) is warranted.

Azmeh R, Lueder GT. Delayed visual maturation in otherwise normal infants. Graefes Arch Clin and Exp Ophthalmol. 2013;251(13):941–944.

Pregeniculate Visual Impairment

Pregeniculate visual impairment denotes visual deficits resulting from pathology anterior to the lateral geniculate nucleus (the pregeniculate visual pathways). Congenital sensory nystagmus may be a clinical indicator of bilateral pregeniculate visual impairment. Strabismus is commonly seen with these disorders. Causes of pregeniculate visual impairment in infants include corneal and other anterior segment abnormalities, glaucoma, retinal disorders, and optic nerve abnormalities.