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Senses

Brushfield spots, visible in the irises of a baby with Down syndrome.

Hearing and vision disorders occur in more than half of people with Down syndrome.

Ocular findings in Down Syndrome

Brushfield spots (small white or grayish/brown spots on the periphery of the iris), upward slanting palpebral fissures (the opening between the upper and lower lids) and epicanthal folds (folds of skin between the upper eyelid and the nose) are clinical signs at birth suggesting the diagnosis of Down syndrome especially in the Western World. None of these requires treatment.

Visually significant congenital cataracts (clouding of the lens of the eye) occur more frequently with Down syndrome. Neonates with Down syndrome should be screened for cataract because early recognition and referral reduce the risk of vision loss from amblyopia. Dot-like opacities in the cortex of the lens (cerulean cataract) are present in up to 50% of people with Down syndrome, but may be followed without treatment if they are not visually significant.

Strabismus, nystagmus and nasolacrimal duct obstruction occur more frequently in children with Down syndrome. Screening for these diagnoses should begin within six months of birth. Strabismus is more often acquired than congenital. Early diagnosis and treatment of strabismus reduces the risk of vision loss from amblyopia. In Down syndrome, the presence of epicanthal folds may give the false impression of strabismus, referred to as pseudostabismus. Nasolacrimal duct obstruction, which causes tearing (epiphora), is more frequently bilateral and multifactorial than in children without Down syndrome.

Refractive error is more common with Down syndrome, though the rate may not differ until after twelve months of age compared to children without Down syndrome. Early screening is recommended to identify and treat significant refractive error with glasses or contact lenses. Poor accommodation (ability to focus on close objects) is associated with Down syndrome, which may mean bifocals are indicated.

In keratoconus, the cornea progressively thins and bulges into a cone shape, causing visual blurring or distortion. Keratoconus first presents in the teen years and progresses into the thirties. Down syndrome is a strong risk factor for developing keratoconus, and onset may be occur at a younger age than in those without Down syndrome. Eye rubbing is also a risk factor for developing keratoconus. It is speculated that chronic eye irritation from blepharitis may increase eye rubbing in Down syndrome, contributing to the increased prevalence of keratoconus.

An association between glaucoma and Down syndrome is often cited. Glaucoma in children with Down syndrome is uncommon, with a prevalence of less than 1%. It is currently unclear if the prevalence of glaucoma in children or adults with Down syndrome differs from that in the absence of Down syndrome.

Pseudostrabismus is the false impression that the eyes are misaligned, which may lead to the incorrect diagnosis of strabismus. Distinguishing between pseudostrabismus and true strabismus is important in newborns, infants and toddlers because untreated strabismus can cause vision loss from reduced depth perception or amblyopia. Acquired pseudostrabismus may be a sign of other eye disease.

The impression of pseudostrabismus in infants and toddlers occurs because the facial features are not fully developed, and the bridge of the nose is wider and flatter. This is especially true when epicanthal folds are present.

In Western populations, the epicanthal folds and associated pseudostrabismus may disappear with age and facial development. Persistent epicanthal folds occur with high frequency in specific Asian and Pacific Island populations, and in indigenous peoples of the Americas.

Facial or eyelid asymmetry, and displacement of the fovea can also cause pseudostrabismus. These may be congenital, or acquired as in cases of orbital tumor, orbital fracture, thyroid eye disease or retinal disease causing foveal displacement, like retinopathy of prematurity or retinal infection.

A skilled observer can distinguish pseudostabismus from strabismus using the corneal light reflex test (also known as the Hirschberg test) and other testing. This evaluation should be performed by an ophthalmologist or other trained professional.