Eyes

Disorders of vision can interfere with a child’s ability to respond to stimuli, learn, and independently perform activities of daily living. The American Academy of Pediatrics recommends that assessment of the eye for children younger than 3 years include ocular history; vision, external eye, and ocular mobility assessments; and pupil and red reflex examinations. For children older than 3 years, the assessment also needs to include age-appropriate visual acuity measurement and ophthalmoscopy (if possible). Early detection and referral can minimize the effects of deficiencies in vision and prevent lifelong impairment. Vision disturbances can alert health practitioners to underlying congenital and acquired disorders.

The eye is composed of three layers. The first, outermost layer consists of the sclera, or white of the eye, which is opaque, and the cornea, which is transparent (Figure 13-1). Underlying the cornea is the iris, which is colored and muscular. At its center is the pupil. The lens lies posterior to the pupil, which is suspended by ciliary muscles. A final layer, the retina, contains rods and cones, which receive visual stimuli and send them to the brain via the optic nerve. The fovea centralis, which appears as a small depression at the back of the retina, contains the most cones. The macula immediately surrounds the fovea centralis. The optic nerve enters the orb through the optic disk. Six muscles hold the eyes in position in their sockets. Coordinated movement of the muscles produces binocular vision. The eyelid, which protects the eye, is lined with the conjunctiva, which is vascular.

At 22 days of gestation the eye appears, and by 8 weeks assumes its familiar form. Its structure and form continue to evolve until the child reaches school age. At birth, myelinization of the nerve fibers is complete and a pupillary response can be elicited. The newborn infant, however, has limited vision.

The neonate is able to identify the mother’s form and is aware of light and motion, as evidenced by the blink reflex. Searching nystagmus is common. The definitive ability to follow objects is not developed until about 4 weeks of life, when the infant is able to follow light and objects to midline. By 8 weeks the infant is able to follow light past midline, although strabismus might be evident.

Intermittent convergent strabismus is common until 6 months of age, then disappears. The muscles assume completely mature function by 1 year. The macula and fovea centralis are structurally differentiated by 4 months. Macular maturation is achieved by 6 years of age. Color discrimination is present between 3 and 5 months. The infant is normally farsighted at birth. Like small children, infants see well at close range. Visual acuity in infants ranges from 20/300 to 20/50 (Table 13-1). The iris usually assumes permanent color by 6 months, but in some children not until 1 year. Lacrimation is present by 6 to 12 weeks of age.

Ask the parent or child if the child seems to see well or if the child seems clumsy, holds books close to eyes, rubs eyes excessively, sits close to the television, has difficulty seeing the board (school-age child), or responds to approaching objects without blinking (infant). Ask if the parents think that the child’s eyes appear unusual or if they have noticed the child’s eyelids drooping or tending to close in an unusual way. Inquire about school performance; the presence of pain, headache, dizziness, or nausea while doing close work; discharge; excessive tearing; squinting; blurred or double vision; burning; itching; and light sensitivity. Alert the physician to any of these symptoms. Inquire about history of eye injuries. Inquire whether there is a family history of vision problems (use of glasses in parents or siblings, glaucoma, color blindness) and whether the child wears glasses, contact lenses, or a prosthesis.

Assessment	Findings
Position and Placement
Note whether the eyes are wide set (hypertelorism) or close set (hypotelorism). Measure the distance between the inner canthi, if in doubt (Figure 13-2).	Inner canthal distance averages 2.5 cm (1 in).
	Wide spaced eyes can be a normal variant in some children.
	Clinical Alert
	Hypertelorism is present in Down syndrome.

Assessment	Findings
	Lid lag and incomplete closure of the eyelid can indicate hyperthyroidism.
Eyebrows
Inspect the eyebrows for symmetry and hair growth.	Eyebrows normally are shaped and move symmetrically.
	They do not meet in midline.
Eyelids
Observe distribution and condition of eyelashes.	Eyelashes curl outward.
Inspect eyelids for color, swelling, discharge (amount, type), and lesions.