Encyclopedia of Health and Medicine

106 The Eyes
People who smoke cigarettes or consume high
quantities of ALCOHOL, particularly in combination,
have a higher risk for developing idiopathic optic
nerve atrophy (in which the cause remains undetermined.
NUTRITIONAL SUPPLEMENTS containing vitamin
A and the antioxidants LUTEIN and ZEAXANTHIN
may improve visual acuity.
See also OPTIC NERVE HYPOPLASIA; RETROBULBAR
OPTIC NEURITIS; TOXIC OPTIC NEUROPATHY.
optic nerve hypoplasia A congenital condition
in which the OPTIC NERVE fails to develop completely
in the unborn child. Optic NERVE hypoplasia
is the third leading cause of congenital vision loss
in the United States. The defect is random and
may affect one EYE or, more commonly, both eyes.
Children who have optic nerve hypoplasia may
have barely noticeable to complete VISION IMPAIR-
MENT depending on the extent to which the optic
nerve develops. Diminished peripheral vision and
depth perception are common. Typically the pediatrician
detects an abnormality of the optic nerve
shortly after birth, though mild optic nerve
hypoplasia may escape notice until the child
begins having vision difficulties. Optic nerve
hypoplasia does not progress, so VISUAL ACUITY typically
remains stable. CORRECTIVE LENSES may
accommodate for vision impairments. Other treatment
focuses on teaching the child adaptive methods.
There are no known preventive measures.
See also AMBLYOPIA; OPTIC NERVE ATROPHY.
optic neuritis See PAPILLITIS.
orbital cellulitis INFLAMMATION and swelling of the
tissues surrounding the EYE, including the eyelids.
Orbital cellulitis requires emergency
medical attention. Delayed treatment
can result in permanent vision loss.
The most common causes are infections that
affect the eyelids such as HORDEOLUM and BLEPHARI-
TIS, DACRYOCYSTITIS (infected tear duct), and infections
of adjacent structures such as SINUSITIS (sinus
infection), PHARYNGITIS (throat infection), tooth
ABSCESS, and occasionally OTITIS media (middle ear
infection). Insect bites that become infected also
can cause orbital cellulitis. Orbital cellulitis may
affect one eye or both eyes, depending on the
underlying cause. The eyelids typically swell
closed and may appear bruised, with considerable
PAIN as well as inability to see. Often there is a
moderate FEVER (above 102ºF) and EXOPHTHALMOS
(bulging of the eye).
The diagnostic path includes assessment of
VISUAL ACUITY and VISUAL FIELD, to the extent possible,
as well as COMPUTED TOMOGRAPHY (CT) SCAN or
MAGNETIC RESONANCE IMAGING (MRI) to visualize the
extent of the infection and determine its site of
origin. Treatment is immediate intravenous ANTIBI-
OTIC MEDICATIONS with hospitalization until fever
and swelling subside. Prompt and appropriate
treatment improves the likelihood for full recovery
and restored vision. Complications can include
increased INTRAOCULAR PRESSURE, which is damaging
to the RETINA and OPTIC NERVE. Because the
optic NERVE presents a direct channel to the BRAIN,
INFECTION also may spread to cause MENINGITIS or
ENCEPHALITIS.
See also CONJUNCTIVITIS; TRAUMA TO THE EYE.