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 unde-
termined. NUTRITIONAL SUPPLEMENTScontaining vita-
min A and the antioxidants LUTEINand 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 com-
pletely in the unborn child. Optic NERVEhypoplasia
is the third leading cause of congenital vision loss
in the United States. The defect is random and
may affect one EYEor, more commonly, both eyes.
Children who have optic nerve hypoplasia may
have barely noticeable to complete VISION IMPAIR-
MENTdepending on the extent to which the optic
nerve develops. Diminished peripheral vision and
depth perception are common. Typically the pedi-
atrician 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 ACUITYtypi-
cally remains stable. CORRECTIVE LENSES may
accommodate for vision impairments. Other treat-
ment focuses on teaching the child adaptive meth-
ods. There are no known preventive measures.
See also AMBLYOPIA; OPTIC NERVE ATROPHY.
optic neuritisSee PAPILLITIS.
orbital cellulitis INFLAMMATIONand 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 HORDEOLUMand BLEPHARI-
TIS, DACRYOCYSTITIS(infected tear duct), and infec-
tions of adjacent structures such as SINUSITIS(sinus
infection), PHARYNGITIS (throat infection), tooth
ABSCESS, and occasionally OTITISmedia (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
PAINas 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 ACUITYand VISUAL FIELD, to the extent possi-
ble, as well as COMPUTED TOMOGRAPHY(CT) SCANor
MAGNETIC RESONANCE IMAGING(MRI) to visualize the
extent of the infection and determine its site of
origin. Treatment is immediate intravenous ANTIBI-
OTIC MEDICATIONSwith hospitalization until fever
and swelling subside. Prompt and appropriate
treatment improves the likelihood for full recov-
ery and restored vision. Complications can include
increased INTRAOCULAR PRESSURE, which is damag-
ing to the RETINAand OPTIC NERVE. Because the
optic NERVEpresents a direct channel to the BRAIN,
INFECTIONalso may spread to cause MENINGITISor
ENCEPHALITIS.
See also CONJUNCTIVITIS; TRAUMA TO THE EYE.106 The Eyes