Disorders of the Eye

Published on 06/06/2015 by admin

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Last modified 06/06/2015

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32 Disorders of the Eye

General pediatricians must be able to identify common ocular problems in infants and children. Many of these conditions can be managed by the pediatrician, but others require referral to an ophthalmologist. Evaluation of the eye and adnexa involves inspection of the eyelids and preauricular lymph nodes; the extraocular movements, confrontational fields, and pupils; red light reflex in young children and fundus examination if indicated; and the globe itself, noting the conjunctiva, cornea, and sclera. Visual acuity can be assessed using several instruments, most commonly the Snellen eye chart. Corneal epithelial defects can be detected by applying fluorescein dye and then illuminating the cornea with a blue-filtered light or Wood’s lamp. Further evaluation by slit lamp and tonometry can be performed by an ophthalmologist if required.

Abnormal Red Light Reflex

All children should have an examination of the red reflex within the first 2 months of life. Children with dark spots in the red reflex, a blunted or absent red reflex, or a white reflex (leukocoria) should be referred to an ophthalmologist. An abnormal red reflex can result from corneal opacities, aqueous opacities, vitreous opacities, and retinal lesions. Leukocoria may indicate pathology, including metabolic, inflammatory, infectious, toxic, oncologic, and traumatic causes; the most common are congenital cataracts and retinoblastoma.

Cataracts

Congenital cataracts occur in two in 10,000 births (Figure 32-1). Of these, 20% to 25% of cases occur secondary to a congenital infection (rubella, cytomegalovirus, or toxoplasmosis) or as a component of a genetic or metabolic condition, such as Turner syndrome, Down syndrome, trisomy 13 and 18, galactosemia, and peroxisomal disorders. Children exposed to high-dose long-term corticosteroid therapy are also at risk, as are children with uveitis or who sustain ocular trauma.

Disorders of Eye Movement

Strabismus

Misalignment of the eyes affects approximately 4% of children younger than 6 years of age (Figure 32-2). Heterophoria is the intermittent tendency for eyes to deviate, and heterotropia is a constant misalignment. The prefixes eso- (inward), exo- (outward), hyper- (upward), and hypo- (downward) indicate the direction of the misaligned eye. Other causes of eye deviations are cranial nerve palsies, intracranial or intraorbital mass, increased intracranial pressure (ICP), and myasthenia gravis.

Heterophorias are usually not apparent; however, under certain conditions such as stress, fatigue, or illness, this latent deviation can be detected. If the deviation is large, patients may experience double vision (diplopia), headache, or eye strain. Heterotropias are present at all times.

Tropias can be tested using the corneal light reflex. The examiner shines a light onto both cornea and notes the placement of the light reflex. If strabismus is present, the reflected light is asymmetric on the cornea. To further test for strabismus, the examiner can perform a cover test. The child should look at an object in the distance. The examiner covers one eye and watches for movement in the uncovered eye. If movement occurs in the uncovered eye, then a misalignment exists in that eye. Phorias can be detected by covering the affected eye; when the eye is uncovered, the practitioner will note the eye moving back into alignment.

Early detection of strabismus is essential because amblyopia can develop if misalignment persists, resulting in permanent visual impairment. Strabismus that is constant or intermittent strabismus that does not correct by age 3 months should prompt ophthalmology referral to begin treatment. The unaffected eye is patched or blurred (with glasses or drops), thereby forcing the strabismic eye to provide a retinal image to the brain and stimulate the proper visual development. In some cases, surgery on the extraocular muscles is necessary to achieve proper alignment.