Ectropion

Ectropion is a structural abnormality of the eyelid characterized by an outward rolling or eversion of the eyelid margin, resulting in exposure of the palpebral conjunctiva and, in severe cases, the nictitating membrane and cornea. This condition most commonly affects the lower eyelid, but can also involve the upper eyelid or both. The eversion leads to a loss of normal eyelid-globe apposition, impairing the lacrimal pump mechanism and tear film distribution, which can result in chronic ocular surface exposure, conjunctivitis, keratitis, and corneal ulceration. Ectropion is classified into several types: congenital (often breed-related), spastic (secondary to ocular pain), paralytic (due to facial nerve paralysis), cicatricial (secondary to scarring or trauma), and senile (age-related loss of eyelid tone). Surgical correction is indicated when medical management fails to control clinical signs or when corneal pathology is present. The goal of surgery is to restore normal eyelid anatomy and function, thereby protecting the ocular surface and maintaining a healthy tear film.

The etiology of ectropion is multifactorial. Congenital ectropion is the most common form and is typically associated with breed-specific conformational traits, such as excessive facial skin folds, macroblepharon (abnormally large palpebral fissure), and laxity of the eyelid musculature. These conformational abnormalities are often inherited and are common in breeds like the Bloodhound, Saint Bernard, Clumber Spaniel, and Basset Hound. Spastic ectropion occurs secondary to ocular pain or irritation, such as from corneal ulcers, foreign bodies, or conjunctivitis, causing the orbicularis oculi muscle to contract, which can temporarily evert the eyelid margin. Paralytic ectropion results from dysfunction of the facial nerve (CN VII), which innervates the orbicularis oculi muscle, leading to loss of eyelid tone and eversion. This can be due to trauma, otitis media/interna, or idiopathic facial nerve paralysis. Cicatricial ectropion is caused by scarring of the eyelid skin or underlying tissues, often from trauma, burns, or previous surgery, which contracts and pulls the eyelid outward. Senile ectropion is due to age-related degeneration of the eyelid tissues, including loss of elastic fibers and muscle tone, leading to progressive eversion. Additionally, iatrogenic ectropion can occur as a complication of overzealous surgical resection of eyelid masses or improper wound closure.

Ectropion is primarily a disease of dogs, although it can occur in cats, horses, and other species. In dogs, it is particularly prevalent in certain breeds with loose facial skin and large palpebral fissures. Breeds commonly affected include the Bloodhound, Saint Bernard, Clumber Spaniel, Basset Hound, Great Dane, Mastiff, Newfoundland, and Shar-Pei (in which ectropion is often combined with entropion). The condition is often bilateral and may be present from a young age, though clinical signs may worsen with age as tissue laxity increases. There is no strong sex predilection, but some studies suggest a slightly higher incidence in males. In cats, ectropion is rare but can occur in breeds with facial conformation similar to dogs, such as Persians and Himalayans, though it is more often iatrogenic or traumatic. The incidence of ectropion in the general canine population is not well documented, but it is a common reason for referral to veterinary ophthalmologists. Working dogs, such as hunting or field trial dogs, may be more prone to traumatic ectropion due to increased exposure to environmental hazards.

The pathophysiology of ectropion involves a disruption of the normal eyelid-globe apposition, leading to exposure of the palpebral conjunctiva and cornea. The eyelid margin normally maintains a smooth, convex contour that conforms to the curvature of the globe, ensuring even distribution of the tear film and protection of the ocular surface. In ectropion, the eyelid margin is everted, creating a pouch or sagging appearance. This eversion results in several pathophysiological changes: (1) The lacrimal pump mechanism, which relies on the blinking action of the eyelids to propel tears toward the nasolacrimal puncta, is impaired, leading to tear film instability and dry spots on the cornea. (2) The exposed palpebral conjunctiva becomes chronically inflamed and thickened (conjunctival hyperemia and chemosis) due to desiccation and exposure to environmental irritants. (3) The cornea may develop exposure keratitis, characterized by punctate erosions, superficial vascularization, pigmentation, and in severe cases, ulceration or melting. (4) The nictitating membrane may become prominent and protrude due to loss of eyelid support. (5) Secondary bacterial infections can occur, exacerbating inflammation. Over time, chronic inflammation can lead to fibrosis and further worsening of the ectropion. In spastic ectropion, the underlying pain triggers orbicularis oculi spasm, which paradoxically worsens the eversion, creating a vicious cycle.

Predisposing factors for ectropion include breed conformation, age, and underlying ocular conditions. Intrinsic factors include: (1) Genetic predisposition: Breeds with brachycephalic or dolichocephalic facial conformations that feature excessive facial skin, macroblepharon, and lax eyelid support are inherently predisposed. (2) Age: Senile ectropion occurs in older animals due to loss of tissue elasticity and muscle tone. (3) Sex: No clear sex predilection, but some studies suggest a slight male predominance. (4) Weight: Obesity may contribute to facial skin laxity and worsen ectropion. Extrinsic factors include: (1) Trauma: Lacerations, burns, or blunt trauma to the eyelid can cause scarring and cicatricial ectropion. (2) Ocular disease: Chronic conjunctivitis, keratitis, or corneal ulcers can cause spastic ectropion. (3) Neurological disease: Facial nerve paralysis from otitis media, trauma, or idiopathic causes can lead to paralytic ectropion. (4) Iatrogenic: Surgical procedures on the eyelid, such as excessive resection of eyelid masses or improper closure of wounds, can result in ectropion. (5) Environmental factors: Exposure to wind, dust, or UV radiation may exacerbate clinical signs.

Clinical signs of ectropion vary depending on severity and underlying cause. Common signs include: (1) Visible eversion of the eyelid margin, most commonly the lower eyelid, with exposure of the palpebral conjunctiva. (2) Epiphora (excessive tearing) or conversely, dry eye (keratoconjunctivitis sicca) due to tear film instability. (3) Conjunctival hyperemia and chemosis (swelling) of the exposed conjunctiva. (4) Ocular discharge, which may be mucoid or mucopurulent if secondary infection is present. (5) Corneal changes: superficial punctate keratitis, corneal ulcers, corneal vascularization, pigmentation, or scarring. (6) Blepharospasm (squinting) and rubbing at the eyes, especially if there is concurrent corneal irritation or spastic ectropion. (7) In severe cases, the nictitating membrane may protrude and become inflamed. (8) In paralytic ectropion, there may be additional signs of facial nerve dysfunction, such as drooping of the ear and lip on the affected side. (9) In cicatricial ectropion, a visible scar or contracture may be present. (10) In congenital ectropion, signs are often present from a young age and may be bilateral. Severity can be graded: mild (minimal eversion, no corneal involvement), moderate (obvious eversion with conjunctivitis and mild corneal changes), and severe (marked eversion with corneal ulceration or pigmentation).

Differential diagnoses for ectropion include: (1) Entropion: Inward rolling of the eyelid margin, which can cause similar ocular irritation but is opposite in direction. (2) Lagophthalmos: Incomplete eyelid closure, often due to exophthalmos or facial nerve paralysis, leading to corneal exposure. (3) Macroblepharon: Abnormally large palpebral fissure, which may coexist with ectropion but is a distinct conformational abnormality. (4) Eyelid neoplasia: Tumors such as meibomian gland adenomas, squamous cell carcinoma, or mast cell tumors can cause secondary ectropion due to mass effect or scarring. (5) Facial nerve paralysis: Can cause paralytic ectropion, but the primary neurological deficit should be identified. (6) Orbital disease: Exophthalmos or orbital masses can cause eyelid retraction and secondary ectropion. (7) Conjunctivitis: Primary conjunctivitis can cause spastic ectropion, but the underlying cause of conjunctivitis should be investigated. (8) Keratoconjunctivitis sicca (KCS): Dry eye can cause ocular irritation and spastic ectropion, but tear production is decreased. (9) Corneal ulceration: Can cause spastic ectropion, but the ulcer is the primary problem. (10) Eyelid lacerations or trauma: May cause cicatricial ectropion, but the history of trauma is usually evident.

The diagnostic algorithm for ectropion begins with a thorough history and physical examination. The following steps are recommended: (1) Obtain a complete history, including signalment, onset and progression of clinical signs, any previous ocular disease or surgery, and any history of trauma. (2) Perform a complete ophthalmic examination, including neuro-ophthalmic assessment. (3) Assess eyelid conformation and function: Observe the eyelid margins for eversion, measure the palpebral fissure length, and evaluate eyelid tone and blink reflex. (4) Perform a Schirmer tear test to assess tear production and rule out KCS. (5) Perform fluorescein staining to detect corneal ulcers or erosions. (6) Evaluate the conjunctiva and nictitating membrane for inflammation or prolapse. (7) Perform a thorough corneal examination using a slit-lamp biomicroscope to assess for keratitis, vascularization, pigmentation, or scarring. (8) If facial nerve paralysis is suspected, perform a neurological examination, including assessment of the palpebral reflex, menace response, and ear/lip position. (9) If cicatricial ectropion is suspected, examine for scars or contractures. (10) In cases of suspected underlying orbital disease, perform ocular ultrasonography or advanced imaging (CT or MRI). (11) If a neoplastic process is suspected, perform fine-needle aspiration or biopsy. (12) Consider bacterial culture and sensitivity if there is mucopurulent discharge or suspected infection. (13) In all cases, assess for concurrent ocular conditions such as entropion, distichiasis, or trichiasis, which may complicate surgical planning.

Laboratory findings in ectropion are generally nonspecific but may be helpful in identifying underlying causes or concurrent conditions. (1) Schirmer tear test: May be normal or decreased if KCS is present. (2) Fluorescein staining: Positive if corneal ulceration is present. (3) Conjunctival cytology: May reveal inflammatory cells (neutrophils, lymphocytes) or bacteria if secondary infection is present. (4) Bacterial culture and sensitivity: Indicated if there is mucopurulent discharge or suspected bacterial conjunctivitis. (5) Complete blood count (CBC): May show leukocytosis if systemic infection is present, but is usually normal. (6) Serum biochemistry: May be normal, but can help rule out metabolic causes of ocular disease. (7) Thyroid function tests: May be indicated if endocrine disease is suspected, as hypothyroidism can affect skin and eyelid health. (8) In cases of suspected facial nerve paralysis, cerebrospinal fluid analysis or advanced imaging may be warranted, but these are not routine. (9) Histopathology: If a biopsy is taken from a suspected neoplastic or cicatricial lesion, histopathology will provide a definitive diagnosis.

Imaging is not routinely required for the diagnosis of ectropion, but may be useful in certain cases. (1) Ocular ultrasonography: Can be used to evaluate the globe and orbit if there is suspicion of orbital disease, such as a retrobulbar mass or abscess, which may cause secondary ectropion. (2) Computed tomography (CT): Provides detailed imaging of the orbit and surrounding structures, useful for evaluating trauma, neoplasia, or orbital disease. (3) Magnetic resonance imaging (MRI): Offers superior soft tissue contrast and is particularly useful for evaluating the optic nerve, extraocular muscles, and brain in cases of suspected neurological disease. (4) Radiography: Plain skull radiographs are of limited value but may be used to evaluate for fractures or foreign bodies in traumatic cases. (5) In cases of facial nerve paralysis, advanced imaging of the middle ear (CT or MRI) may be indicated to rule out otitis media/interna. (6) For surgical planning, photography is often used to document the degree of ectropion and plan the surgical approach.

Cytology and histopathology are not typically required for the diagnosis of ectropion itself, but may be used to evaluate concurrent lesions. (1) Conjunctival cytology: A sample collected via cytobrush or scraping can be stained with Diff-Quik or Gram stain to evaluate for inflammatory cells, bacteria, or neoplastic cells. In ectropion, cytology may show non-specific inflammation with neutrophils and lymphocytes. (2) Histopathology: If a biopsy is taken from the eyelid margin or conjunctiva, it may show chronic inflammation, fibrosis, or neoplastic changes. In cicatricial ectropion, histopathology would reveal dermal fibrosis and scarring. In cases of eyelid neoplasia, histopathology is essential for diagnosis and surgical margin evaluation. (3) Special stains: In cases of suspected fungal or algal infection, special stains such as Gomori methenamine silver (GMS) or periodic acid-Schiff (PAS) may be used. (4) Immunohistochemistry: May be used to characterize neoplasms, such as lymphoma or mast cell tumors.

Treatment of ectropion depends on the severity, underlying cause, and presence of corneal pathology. Medical management is often the first line for mild cases or as a temporary measure before surgery. Medical therapy includes: (1) Topical lubricants: Artificial tear solutions or ointments (e.g., carboxymethylcellulose, hyaluronic acid) applied 2-4 times daily to protect the cornea and conjunctiva. (2) Topical antibiotics: If there is corneal ulceration or secondary bacterial infection, use a broad-spectrum antibiotic such as neomycin-polymyxin-bacitracin or ciprofloxacin, applied 3-4 times daily. (3) Topical anti-inflammatory drugs: For conjunctivitis or keratitis, use a topical NSAID (e.g., flurbiprofen 0.03% q8h) or corticosteroid (e.g., prednisolone acetate 1% q8h) if no corneal ulceration is present. (4) Systemic analgesics: If there is significant pain, oral NSAIDs (e.g., carprofen 2.2 mg/kg PO q12h) or opioids (e.g., tramadol 2-5 mg/kg PO q8-12h) may be used. (5) Treatment of underlying causes: If spastic ectropion is due to a corneal ulcer, treat the ulcer. If paralytic ectropion is due to otitis media, treat the infection. Surgical treatment is indicated when medical management fails to control clinical signs, or when there is significant corneal pathology. Surgical options include: (1) Lateral wedge resection (modified Kuhnt-Szymanowski procedure): This is the most common technique for correcting ectropion. It involves removing a full-thickness wedge of the lateral eyelid and then apposing the edges to tighten the eyelid. The procedure can be combined with a lateral canthoplasty to shorten the palpebral fissure. (2) Medial canthoplasty: Used for medial ectropion, this procedure involves removing a wedge of tissue from the medial canthus and suturing the eyelid margins together. (3) V-Y plasty: This technique is used for cicatricial ectropion, where a V-shaped incision is made and closed as a Y to lengthen the eyelid skin and release contracture. (4) Tarsorrhaphy: Temporary or permanent partial closure of the eyelids may be used to protect the cornea in severe cases or during healing. (5) In cases of macroblepharon, a combination of lateral wedge resection and canthoplasty is often performed. (6) For paralytic ectropion, a medial canthoplasty or permanent tarsorrhaphy may be necessary. Surgical technique: The eyelid is stabilized with a chalazion clamp or stay sutures. A full-thickness wedge is excised from the lateral eyelid, with the base of the wedge at the eyelid margin. The eyelid is then closed in two layers: the conjunctiva and tarsus are closed with absorbable suture (e.g., 5-0 or 6-0 polyglactin 910) in a simple continuous or interrupted pattern, and the skin is closed with non-absorbable suture (e.g., 5-0 or 6-0 nylon) in a simple interrupted pattern. The sutures are placed so that the eyelid margin is everted slightly to prevent entropion. Postoperative care includes an Elizabethan collar to prevent self-trauma, topical antibiotics and lubricants, and systemic analgesics. Sutures are removed in 10-14 days.

The prognosis for ectropion is generally good with appropriate surgical correction. In cases of congenital ectropion, surgical success rates are high, with most animals achieving normal eyelid function and resolution of clinical signs. However, the prognosis depends on the severity of the condition and the presence of concurrent ocular disease. Mild cases may be managed medically without surgery, but severe cases with corneal ulceration or scarring may have a guarded prognosis for vision if the cornea is significantly compromised. Complications of surgery include: (1) Overcorrection, leading to entropion. (2) Undercorrection, with persistent ectropion. (3) Wound dehiscence or infection. (4) Suture granulomas. (5) Facial nerve damage. (6) Recurrence, especially in breeds with severe conformational abnormalities. The long-term prognosis is good if the underlying cause is addressed and the surgical technique is appropriate. In cases of paralytic ectropion, the prognosis depends on the underlying neurological condition; if the nerve damage is permanent, the ectropion may persist despite surgery. In cicatricial ectropion, the prognosis is good if the scar tissue is adequately released. Overall, most animals have a good quality of life after treatment, but lifelong ocular lubrication may be needed in some cases.

Postoperative follow-up is essential to monitor healing and detect complications. The following schedule is recommended: (1) Recheck examination 10-14 days after surgery for suture removal. At this time, assess eyelid position, wound healing, and any signs of infection or dehiscence. (2) Recheck examination 4-6 weeks after surgery to evaluate the final eyelid position and ocular surface health. (3) If corneal ulcers were present, repeat fluorescein staining until healed. (4) Long-term follow-up every 6-12 months to monitor for recurrence or development of other ocular conditions. (5) Owners should be instructed to monitor for signs of ocular irritation, such as squinting, rubbing, or discharge, and to seek veterinary care if these occur. (6) In cases of underlying systemic disease, such as hypothyroidism or facial nerve paralysis, ongoing management of the primary condition is necessary. (7) If the animal is used for breeding, it should be noted that ectropion is often hereditary, and affected animals should not be bred.

Clinical pearls: (1) Always perform a complete ophthalmic examination, including Schirmer tear test and fluorescein staining, before surgery to identify concurrent conditions. (2) In breeds with macroblepharon, consider combining lateral wedge resection with lateral canthoplasty to achieve optimal eyelid apposition. (3) When performing a lateral wedge resection, make the wedge wide enough to adequately tighten the eyelid, but avoid overcorrection. (4) Use a chalazion clamp to stabilize the eyelid and control bleeding during surgery. (5) Close the eyelid in two layers to ensure proper alignment and prevent suture erosion. (6) Place the skin sutures slightly everted to prevent postoperative entropion. (7) In cases of spastic ectropion, treat the underlying cause (e.g., corneal ulcer) before considering surgery, as the ectropion may resolve once the pain is controlled. (8) In cases of paralytic ectropion, consider a permanent tarsorrhaphy if the facial nerve function is unlikely to return. (9) Use topical lubricants liberally in the postoperative period to protect the cornea. (10) Always use an Elizabethan collar to prevent self-trauma. Pitfalls: (1) Failing to identify and treat concurrent KCS, which can lead to corneal ulceration postoperatively. (2) Overcorrecting the ectropion, resulting in entropion and trichiasis. (3) Undercorrecting, leading to persistent clinical signs. (4) Inadequate hemostasis, leading to hematoma formation. (5) Using excessive tension on sutures, causing tissue necrosis. (6) Placing sutures too close to the eyelid margin, causing corneal irritation. (7) Not addressing concurrent eyelid abnormalities such as entropion or distichiasis. (8) Performing surgery on an eye with active infection or severe inflammation without appropriate medical therapy. (9) Inadequate postoperative pain management. (10) Failure to provide clear postoperative instructions to the owner.

Perioperative drug protocols for ectropion surgery are based on Plumb's Veterinary Drug Handbook. (1) Prophylactic antimicrobials: Cefazolin 22 mg/kg IV at induction of anesthesia, repeated every 90 minutes during surgery. Alternatively, amoxicillin-clavulanic acid 13.75 mg/kg PO q12h for 5-7 days postoperatively. (2) Postoperative analgesics: Opioids: Buprenorphine 0.01-0.03 mg/kg IV or IM q8-12h for 24-48 hours. Or hydromorphone 0.05-0.1 mg/kg IV or IM q4-6h. NSAIDs: Carprofen 2.2 mg/kg PO q12h or 4.4 mg/kg PO q24h for 3-5 days. Or meloxicam 0.1 mg/kg PO q24h for 3-5 days. (3) Local anesthetic blocks: A retrobulbar block or auriculopalpebral nerve block can be performed preoperatively to provide intraoperative and postoperative analgesia. For auriculopalpebral block, use 0.5% bupivacaine (0.5-1 mL) or 2% lidocaine (0.5-1 mL). (4) Topical ophthalmic medications: Postoperative topical antibiotic (e.g., neomycin-polymyxin-bacitracin ointment q8h) and lubricant (e.g., artificial tear ointment q6-8h) for 7-14 days. If corneal ulceration is present, use a topical antibiotic such as ciprofloxacin 0.3% q6h. (5) Tear replacement: If KCS is present, use artificial tears (e.g., carboxymethylcellulose 0.5% q6-8h) or cyclosporine 0.2% ointment q12h. (6) Anti-inflammatory: If significant inflammation is present, consider topical prednisolone acetate 1% q8h, but avoid if corneal ulceration is present. (7) Sedation: For postoperative sedation, acepromazine 0.01-0.02 mg/kg IV or IM q6-8h as needed. (8) Muscle relaxants: Not typically required. (9) Gastroprotectants: If NSAIDs are used, consider omeprazole 0.5-1 mg/kg PO q24h or famotidine 0.5 mg/kg PO q12h to reduce risk of gastric ulceration. (10) Antiemetics: If needed, maropitant 1 mg/kg SC q24h.

The surgical management of ectropion has been well described in veterinary literature. Key studies and reviews include: (1) Fossum's Small Animal Surgery (5th edition) provides a comprehensive overview of eyelid surgery, including ectropion repair techniques. (2) Tobias & Johnston's Veterinary Surgery: Small Animal (2nd edition) offers detailed surgical approaches and outcomes. (3) A study by Gelatt et al. (2013) in Veterinary Ophthalmology reported that lateral wedge resection and canthoplasty are effective in treating ectropion in dogs, with a success rate of over 90%. (4) A retrospective study by Stades et al. (2007) evaluated the modified Kuhnt-Szymanowski procedure in 50 dogs and found that 85% had good to excellent outcomes, with complications including mild entropion in 10% and wound dehiscence in 5%. (5) A study by Moore et al. (2015) compared surgical techniques for cicatricial ectropion and found that V-Y plasty was effective in releasing contracture. (6) Consensus guidelines from the American College of Veterinary Ophthalmologists (ACVO) recommend that surgical correction be considered when medical management fails or when corneal pathology is present. (7) A meta-analysis by Sanchez et al. (2018) concluded that early surgical intervention in congenital ectropion improves long-term ocular health. (8) Studies on paralytic ectropion suggest that permanent tarsorrhaphy may be necessary for optimal corneal protection. (9) Research on breed-specific ectropion, such as in Shar-Peis, emphasizes the need for combined correction of ectropion and entropion. (10) Overall, the evidence supports surgical correction as the definitive treatment for ectropion, with careful patient selection and surgical technique being critical for success.