Entropion, which is an inversion of the eyelid’s margin, can be a mild problem or pose severe health consequences, as misshapen tissues may induce corneal abrasion and lead to blindness. Endemic infectious disease affecting the eyes in developing countries may induce entropion in vulnerable groups when there is no genetic predisposition to the condition.
Definition & Facts
The eyelid protects the eye’s cornea upon opening and protects it upon closing. Conditions that commonly affect the eyelid include too few tears to lubricate the space between eyelid and eyeball (dry eye syndrome) or inflammation of the cornea (keratitis).
Entropion, a folding of the eyelashes to a position under the eyelid, is characterized by how the eyelashes and eyelid interact to affect the eye. These categories include involutional, spastic, cicatricial, and congenital. In "generic" entropion the eyelid folds in on itself (i.e., “inversion”), causing lashes to abrade the cornea. This abrasion is painful and may be accompanied by infection.
Symptoms & Complaints
When the eyelid is folded under during normal blinking, tears do not refresh the cornea. When eyelids are blinked with extra pressure, a transient inversion of eyelid may occur. This eyelid inversion typically involves the lower eyelid. Failure to treat may result in blindness.
Demographics play a role. Entropion often manifests with aging. It is more common among the elderly population, affecting about two out of every 100 seniors. Geographical regions with endemic diseases that affect the eye (for example, trachoma which the World Health Organization reports affects 241 million people) may have populations that suffer disproportionately from entropion.
Normally the eyelid has physical contact with the eyeball, lubricated by tears. Eyelid pressure against the eyeball is dependent on musculature and tendons that may stretch or weaken with age. When these structures weaken unevenly, the eyelid margin may begin to turn in, inverting so that the outside of the eyelid’s edge is turned inward, inducing corneal abrasion.
Eyelid integrity relates to genetics, familial predisposition, congenital conditions, infectious disease and inflammation, surgical or physical trauma (including head trauma, heat-induced burns or chemical burns), paresis, scarring, and muscle weakness associated with other maladies. Any of these may degrade eyelid shape and cause problems with the orientation of the eyelid to the cornea.
Patients may respond to itching or irritated eyes by aggressively rubbing the eyelid. Spasms related to that rubbing comprise the “spastic” version of entropion when spasm causes the inward moving of the eyelid against the cornea.
Diagnosis & Tests
The diagnostic process begins with patients presenting their complaints to a health care provider. Diagnosis then involves developing a history of the complaint including its onset, manifestations, resolution, repetitive incidence, and previous evaluations if any. Clinical examination establishes physical status and rules out such causal factors as a foreign body in the eye.
Eye specifics will be studied and condition of the eye established. Evaluation details inflammation, degree of tearing present, character of discharge from the eye, and extent of corneal erosion. Epithelial abrasion will manifest in about 6 out of 10 patients presenting with entropion complaints.
Special tests will be performed. The snap-back test is performed by the clinician drawing the lower eyelid down or away from the eyeball to evaluate the eyelid’s elasticity (ability and latency in returning to normal position without blinking).
A slit-lamp examination may also be performed to assess how dry the eye is and the extent of damage or injury to the cornea. The physical may also check to see if the tear ducts are blocked. Tear production can be assessed through the Schirmer test as well.
Treatment & Therapy
The diagnosis of underlying causes will determine the kind of intervention necessary. For example, if active infection is inducing entropion, resolving the infection will resolve the entropion. Treating the infection and associated swelling may allow displaced tissues to return to their previous healthy position and return normal eyelid function.
Simple skin tape may be applied to preclude the eyelid’s inversion. When the concern is primarily eyeball abrasion, a protective soft contact lens may be useful to insulate the eyeball from further abrasion. When entropion results from eyelid muscle imbalance in the eyelid, Botox can weaken the offending muscle, but long-term effectiveness requires repeated treatments.
Unfortunately, minimal procedures fail to provide consistent long-term results but surgery may still be pursued. Specific surgical procedures will vary according to the specific diagnosis and eyelid tissues involved. They can range from simple eyelid suture or stitches to physically changing eyelid shape.
Muscle and tendon structures can be stiffened by removal of a portion of the eyelid and tying the remaining tissues together with sutures. Where eyelid structures have been scarred or thickened from trauma or burns, mucous membranes may be harvested from the nasal-oral cavity and implanted under the eyelid (a mucosal graft). Surgical follow-up includes use of antibiotics, cold packs to minimize swelling and pain, and removal of stitches.
Prevention & Prophylaxis
To the extent that entropion is caused by injury or trauma to the eyes, safety goggles and other forms of eye protection should be worn when working around dangerous chemical substances or in fields like welding and construction.