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What is Ocular Entropion?
Entropion is an abnormal inward rotation of the eyelid margin: the edge of the eyelid folds toward the eye rather than lying flat against the eyeball. It can affect either the upper or lower eyelid, though the lower eyelid is more commonly involved.
When the eyelid turns inward, the eyelashes and the inner skin of the lid make continuous contact with the surface of the cornea (the transparent front surface of the eye) and the conjunctiva (the clear membrane covering the white of the eye). This constant rubbing triggers irritation and inflammation. If left untreated, it can cause progressive corneal damage, ranging from superficial punctate keratitis to deep corneal ulceration, and may ultimately lead to permanent vision loss.
The main symptoms experienced by patients include:
- Eye redness
- Eye pain
- Excessive sensitivity to light (photophobia) and wind
- Excessive tearing (epiphora)
- Foreign body sensation in the eye
- Involuntary, persistent eyelid closure (blepharospasm)
- Reduced visual acuity (in advanced stages with corneal damage)
Entropion should never be dismissed as a minor inconvenience. If left untreated, it can progressively damage the cornea and lead to irreversible vision impairment or blindness. Timely specialist assessment and treatment are essential.
How the Eye Works
Understanding why entropion is potentially serious requires a brief overview of how the eye functions:
- Cornea and lens: positioned at the front of the eyeball, they focus incoming light and project a clear image onto the retina.
- Retina: a light-sensitive tissue lining the back of the eye, converting visual stimuli into electrical signals.
- Optic nerve: transmits electrical signals from the retina to the brain, which interprets them as vision.
The cornea, a transparent, avascular structure, depends on its smooth, intact surface for clear vision. It is also among the most densely innervated tissues in the body, explaining why corneal contact with the eyelid or lashes is so immediately and intensely painful.
In entropion, repeated mechanical friction against the cornea can cause scarring and opacification, a clouding of the normally transparent cornea that impairs the passage of light and deteriorates vision, sometimes irreversibly.
Causes
Several conditions can cause or contribute to entropion:
Age-Related (Involutional) Entropion
The most common cause worldwide. As the tissues around the eye age, three main changes occur:
- Horizontal laxity of the lower eyelid (where the eyelid becomes loose and less taut against the eyeball).
- Hypercontraction of the orbicularis oculi muscle: The circular muscle around the eye becomes overactive, pulling the lid margin inward.
- Disinsertion or laxity of the lower eyelid retractors: The fibrous structures that normally maintain the lower lid in its correct position weaken and detach. This allows the lid to rotate inward.
These changes combine to produce the classic involutional entropion of elderly patients.
Cicatricial Entropion
Scarring of the inner surface of the eyelid (conjunctiva or tarsal plate) can deform the lid’s natural curvature and pull it inward. Causes of scarring include:
- Previous trauma or eyelid injuries
- Prior eyelid surgery
- Chemical or thermal burns
- Radiotherapy to the periorbital area
- Chronic inflammatory diseases (see trachoma below)
- Stevens-Johnson syndrome and other mucocutaneous disorders
Spastic Entropion
Acute or chronic inflammation, infection, or irritation of the eye can trigger reflex overcontraction of the orbicularis oculi muscle, causing the eyelid margin to rotate inward. This is often a temporary or intermittent form of entropion that resolves when the underlying irritation is treated. It can also be triggered by ocular surgery or prolonged patching of the eye.
Trachoma
Trachoma is a chronic bacterial eye infection caused by Chlamydia trachomatis. It is the world’s leading infectious cause of preventable blindness. Endemic in many low-income countries, it spreads through direct contact with infected eye or nasal secretions, or indirectly through shared personal items (towels, clothing). Repeated infections lead to progressive conjunctival scarring. Over time, this scarring deforms the eyelid, resulting in trachomatous trichiasis (inward-turning lashes) and cicatricial entropion. These conditions can then cause subsequent corneal damage.
Congenital Entropion
Rarely, entropion is present from birth, resulting from developmental anomalies in eyelid structure. It is more common in certain ethnic groups, particularly East Asian populations, where a horizontal fold of skin (called the epicanthus) can push the lashes against the cornea.
Symptoms
In entropion, the inwardly rotated eyelid margin and lashes continuously rub against the ocular surface, producing the following symptoms:
- Eye redness: conjunctival injection (redness) from chronic irritation.
- Eye pain: often described as a sharp or burning discomfort, worsened by blinking or eye movement.
- Photophobia: abnormal sensitivity to light and wind or air drafts
- Epiphora (excessive tearing): tears overflow onto the cheek rather than draining normally through the nasolacrimal duct, because the punctum (the small drainage opening at the inner eyelid margin) is displaced by the rotated lid.
- Foreign body sensation: a persistent feeling that something is in the eye. For example, lashes touching the cornea may be perceived as a foreign object.
- Eyelid crusting: discharge and crusting along the eyelid margin, particularly on waking (in some cases).
- Involuntary eyelid closure: the discomfort triggers reflex protective closure of the eye (blepharospasm)
- Reduced visual acuity: in advanced stages, corneal scarring and opacity progressively impair vision
Complications
If entropion is not recognized and corrected, the ongoing mechanical trauma to the cornea causes progressively more severe damage:
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Corneal abrasions: superficial scratches on the corneal epithelium, causing acute pain and redness. While these can heal rapidly if the source of irritation is removed, they recur continuously in untreated entropion.
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Corneal ulcers: deeper defects in the corneal tissue, which may become infected (bacterial, fungal, or viral keratitis) and expand rapidly. Corneal ulcers require urgent ophthalmological treatment.
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Corneal scarring and opacification: scar tissue replacing the transparent corneal stroma permanently impairs light transmission and vision. This damage is irreversible without corneal transplantation.
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Blindness: the end stage of severe, neglected entropion, particularly in cases linked to trachoma, results in permanent and irreversible vision loss.
The key clinical message: the earlier entropion is treated, the less corneal damage occurs and the better the visual outcome.
Diagnosis
The diagnosis of entropion is primarily clinical. It is made by an ophthalmologist, or eye specialist, through direct examination. No laboratory tests are needed.
Examination Findings
The inwardly rotated eyelid margin and misdirected eyelashes are visible on inspection. If the lid happens to be in a normal position during the examination (which can occur in intermittent entropion), the ophthalmologist will ask the patient to gently close and open their eyes repeatedly. This action often reproduces the inward rotation.
Slit-Lamp Examination
The slit lamp (a biomicroscope providing magnified, illuminated views of the anterior eye) allows detailed assessment of:
- The eyelid margin position and rotation
- Lash contact with the conjunctiva and cornea
- Conjunctival redness, follicles, or scarring (suggesting chronic inflammation or trachoma)
- Corneal epithelial defects, abrasions, ulcers, or scarring (using fluorescein dye, which makes epithelial defects visible under blue light)
Pinch Test (Snap-Back Test)
A simple bedside test of lower eyelid laxity:
- The examiner grasps the lower eyelid between thumb and index finger and pulls it away from the eyeball
- The maximum distance of separation is measured, and the time taken for the lid to return to the eyeball on release is assessed
Normal: the lower lid separates by no more than 4–5 mm and snaps back immediately on release.
Abnormal findings indicate laxity and are graded:
- Moderate: displacement of 5–7 mm
- Severe: displacement of 7–9 mm
- Marked: displacement exceeding 11 mm
Greater laxity indicates more significant structural weakness and predicts the need for surgical correction.
Additional Assessment
In cases where trachoma or other systemic diseases are suspected, additional investigations (conjunctival swabs, systemic workup) may be indicated. When corneal involvement is significant, the ophthalmologist will assess corneal sensation, measure visual acuity, and document the extent of corneal damage.
Treatment
Treatment is determined by:
- The underlying cause of the entropion.
- The severity of lid malposition.
- The current state of the cornea: the priority is to prevent further damage while awaiting or planning definitive treatment.
Temporary and Symptomatic Measures
Eyelid taping: adhesive strips (medical tape or specialized eyelid tapes) are applied to the lower lid to manually evert it away from the eye and maintain it in the correct position. This is a practical temporary solution, particularly while awaiting surgery, that protects the cornea from further friction.
Botulinum toxin injections: in spastic entropion caused by orbicularis oculi muscle overcontraction, a small injection of botulinum toxin (Botox) into the overactive muscle reduces its contractile force, relieving the inward rotation. The effect lasts 3–6 months and may be repeated. This is an effective non-surgical option for spastic or intermittent entropion.
Lubricating and protective eye drops and ointments: prescribed to:
- Keep the ocular surface moist and lubricated, reducing friction
- Protect the cornea from desiccation
- Relieve symptoms of irritation
- Treat any concurrent infection (antibiotic drops or ointment if bacterial infection is present)
- Promote re-epithelialization of corneal abrasions (epitheliotrophic eye drops)
Therapeutic contact lenses: bandage soft contact lenses can be applied over the cornea as a physical shield, protecting it from lash friction while other treatments take effect or while the patient awaits surgery.
Surgical Treatment
Surgery is the definitive treatment for entropion and is indicated when:
- The entropion is unlikely to resolve spontaneously or with temporary measures
- Eyelid laxity is significant (as quantified by the pinch test)
- Corneal damage is present or at high risk of progression
The goal of surgery is to restore the eyelid margin to its correct, outward-facing position and to correct the underlying structural abnormality causing the malposition.
The procedure is typically performed under local anesthesia and takes approximately 40 minutes. The specific surgical technique depends on the cause:
- For involutional (age-related) entropion: the most common procedures tighten and reattach the lower eyelid retractors and correct horizontal laxity. These steps effectively “re-tension” the loose eyelid and rotate the lid margin back to its normal position. Techniques include the Quickert procedure, retractor reinsertion, and the Jones procedure with horizontal lid shortening.
- For cicatricial entropion: in addition to correcting the lid position, the scarred posterior lamella (inner surface of the lid) may need to be replaced with a graft of mucous membrane (e.g., from the inside of the cheek) to restore normal lid architecture.
- For congenital entropion: similar principles apply; the surgical approach is adapted to the specific anatomical anomaly present.
Prognosis: if surgery is performed before the cornea has sustained irreversible damage, the prognosis for both symptom resolution and visual preservation is excellent. However, because eyelid laxity tends to progress with further aging, a small proportion of patients may require repeat surgery over time.
Sources and Bibliography
- Marcet MM, Phelps PO, Lai JS. Involutional entropion: risk factors and surgical remedies. Curr Opin Ophthalmol. 2015 Jul;26(5):416-21. doi: 10.1097/ICU.0000000000000186.
- Tonk RS, Meyer DR. Manual Provocation Test for Intermittent Involutional Entropion. Cornea. 2016 Apr;35(4):510-2. doi: 10.1097/ICO.0000000000000762.
- Peduzzi M. Manuale d’oculistica, 3rd edition. Milan: McGraw-Hill, 2004. ISBN 978-88-386-2389-9.
- Nerad JA. Techniques in Ophthalmic Plastic Surgery. Philadelphia: Saunders Elsevier, 2010.
- World Health Organization. Trachoma Fact Sheet. who.int
