E

ectropion Loss of elasticity or control of the eye-
lid, usually the lower eyelid, that causes it to sag
away from the EYE. Ectropion allows tears to over-
flow the lid rather than remaining in the eye. It
also fails to protect the eye, and especially the
CORNEA, permitting dryness and exposure to envi-
ronmental particles that create irritation and pos-
sibly injury to the cornea and sclera (“white” of
the eye). Common causes of ectropion include

• aging


• damage to the nerves that control the eyelids


• CICATRICIAL PEMPHIGOID

Ectropion is a common symptom of BELL’S
PALSY, a temporary paralysis of one side of the face
that results from INFLAMMATIONof the seventh cra-
nial NERVE(facial nerve), and also may accompany
neurologic disorders such as PARKINSON’S DISEASE
and MULTIPLE SCLEROSIS.
With ectropion the eye feels irritated and
scratchy. Tear production becomes excessive as the
eye attempts to lubricate and protect itself, and
tears typically run over the lip of the lid and onto
the cheeks. The doctor can diagnose ectropion
based on its appearance. Treatment is typically
surgery to tighten the lid structure to permit the
lid to stay against the eye. Whether the ectropion
recurs depends on the underlying cause.
Untreated ectropion may result in extensive dam-
age to the surface of the eye and cornea, including
INFECTION, that interferes with vision and the
health of the eye.
See also AGING, VISION AND EYE CHANGES THAT
OCCUR WITH; CONJUNCTIVITIS; CORNEAL INJURY; CRANIAL
NERVES; ENTROPION; KERATITIS.

electroretinography A test that measures the

electrical activity of the RETINA’s rods and cones in

response to light stimulation. The ophthalmologist

places anesthetic drops in the EYEto numb it, then

attaches an electrode to the surface of the CORNEA.

The electrode detects electrical impulses on the

retina when the ophthalmologist flashes a beam of

light onto the retina, and sends signals to the elec-

troretinograph machine. An electroretinogram is

the recording the machine makes of the retina’s

responses. Electroretinography helps diagnose dis-

orders of the retina such as RETINAL DETACHMENT

and RETINITIS PIGMENTOSA.

See also DARK ADAPTATION TEST; RETINOPATHY; SLIT

LAMP EXAMINATION.

entropion Deformity of the eyelid in which the

lip of the lid, including the eyelashes, curls inward

toward the EYE. Scarring that results from CICATRI-

CIAL PEMPHIGOID(an AUTOIMMUNE DISORDERin which

painful blisters repeatedly form on the insides of

the eyelids) or recurrent CONJUNCTIVITIS(INFLAMMA-

TIONor INFECTIONof the inner lining of the eyelids)

is a common cause of entropion. Entropion may

also develop for unknown reasons (idiopathic).

The ophthalmologist can diagnose entropion by its

presentation. The irritation of the lid and lashes

against the surface of the eye is painful and can

cause significant damage to the CORNEA, resulting

in VISION IMPAIRMENT and perhaps the need for

CORNEAL TRANSPLANTATION. Treatment seeks to

relieve the irritation. In mild entropion, lubricat-

ing eye drops may be sufficient to protect the eye.

Moderate to severe entropion requires surgery to

restore the eyelid to its appropriate structure.

Once corrected, entropion usually does not recur.

See also CORNEAL INJURY; ECTROPION; KERATITIS.

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