Protrusion of Third Eyelid in Cats

Protrusion of Third Eyelid in CatsProtrusion of Third Eyelid in Cats
Protrusion of Third Eyelid in CatsProtrusion of Third Eyelid in Cats

Overview of Protrusion of Third Eyelid in Cats

Protrusion, prolapse or elevation of the third eyelid, sometimes referred to as “cherry eye”, refers to the abnormal elevation of the smooth inner eyelid that is located between the cornea and the inside corner of the eyelids closest to the nose. The third eyelid (TE) is usually retracted beneath the eyelids and barely noticeable. The third eyelid is also sometimes called the membrana nictitans or nictitating membrane.

Below is an overview of information about Protrusion of Third Eyelid in Cats followed by detailed information about the diagnosis and treatment options.

Causes of Feline Third Eyelid Protrusion 

Numerous disorders affecting the eye, TE and soft tissues behind the eye can result in TE protrusion. Therefore, TE protrusion represents a nonspecific symptom of ophthalmic disease that warrants further diagnostic evaluation.

The causes of protrusion of the TE fall into several categories:

  • Decreased or loss of function of the nerve supply to the smooth muscles of the TE and those surrounding the eyeball, from certain neurologic or systemic diseases
  • Relaxation of the muscles around the eyeball that work to keep the TE in the retracted position, from the use of tranquilizers, from poor physical health, etc.
  • Weakening of the ligament of the gland of the third eyelid with secondary glandular enlargement and prolapse (also known as cherry eye)
  • Tumors, cysts or inflammatory diseases of the TE
  • Any source of ocular (eye) pain that stimulates retraction of the eye deeper into the orbit (bony cavity in the skull or eye socket)
  • Any cause of settling of the eye deeper into the bony socket, such as from dehydration, weight loss, or changes in the structures behind the eye
  • Abnormally small sized eye. Small eyes may occur as congenital birth defects or may arise from shrinkage of the eye following severe trauma or inflammation.
  • Presence of a mass, such as a tumor, cyst, infection or inflammation within the orbit, and pushing the eye and the TE forward

What to Watch For

  • Increased prominence and elevation of the smooth inner membrane located at the inside corner of the eyelids
  • Other signs are dependent upon the cause of the prolapse. They may include squinting, tearing, changes in pupil size, alterations in the size or position of the eyeball, discoloration of the third eyelid, and deformities of the third eyelid.
  • The condition may affect one or both third eyelids.

Diagnosis of Protrusion of Third Eyelid in Cats

Diagnostic tests may include one or more of the following:

  • Complete medical history and physical examination
  • Complete ophthalmic examination including testing of pupillary light reflexes, Schirmer tear test, fluorescein staining of the cornea, tonometry to measure the pressure within the eye, and examination of the interior of the eye under magnification. Your veterinarian may refer your cat to a veterinary ophthalmologist for further evaluation using specialized instrumentation.
  • The third eyelid itself may be examined with a forceps after application of a local anesthetic.
  • Neurologic examination to assess the presence of neurologic disease
  • Complete blood count (CBC) and serum biochemistry tests to evaluate the underlying cause and identify any related problems
  • Skull X-rays to determine the presence of a bony orbital or sinus problem
  • Ultrasound examination of the eye and soft tissues within the orbit behind the eye
  • Specialized imaging tests such as computed tomography (CT) scan and magnetic resonance imaging (MRI) of the eye, orbit and brain

Treatment of Protrusion of Third Eyelid in Cats

Successful treatment requires obtaining an accurate diagnosis as to the cause. No symptomatic therapy can be initiated until the precise cause of TE elevation is identified.

Home Care for Protrusion of Third Eyelid in Cats

Vision is not usually compromised unless the third eyelid covers more than half of the eye. The underlying cause of the prolapse may affect vision, however. Confine your pet to a safe area until the cause of the problem is determined.

Do not administer human over-the-counter medications, such as Visine® or other ophthalmic remedies intended to “reduce eye redness” or irritation, because these medications rarely help the problem and may make diagnosis of the cause more difficult.

 

In-depth Information on Protrusion of Third Eyelid in Cats

Elevation, prolapse or protrusion of the third eyelid (membrana nictitans, nictitating membrane) refers to the abnormal elevation of the smooth inner eyelid that is located between the cornea and the inside corner of the eyelids closest to the nose. The third eyelid (TE) is usually retracted beneath the eyelids and barely noticeable. The ability to move the TE is involuntary in most animals; however, cats have some control over the movement of this membrane.

Numerous disorders affecting the eye, the tissues in the orbit behind the eye, and the neurologic functions around the eye can result in TE protrusion. In addition, certain systemic diseases and medications can also cause this condition. Therefore, TE protrusion in an animal represents a nonspecific symptom that warrants further diagnostic evaluation by a veterinarian to determine its exact cause.

Neurologic causes of prolapse of the third eyelid include the following:

  • Horner’s syndrome is a neurologic disease that arises from dysfunction of the sympathetic nerves to the eye. The sympathetic nervous system controls many glandular and involuntary functions in the body. Prolapse of the third eyelid is one of four clinical signs that develop with Horner’s syndrome. Horner’s syndrome usually affects only one eye at a time.
  • Damage to cranial nerves III or VI that control muscles around and behind the eye may result in TE protrusion on the affected side, but damage to these nerves is rare.
  • Dysautonomia is another extremely rare neurologic disease that causes widespread dysfunction of the autonomic nervous system resulting in bilateral dilation of the pupils, decreased tear production and protrusion of the TE, in addition to serious systemic symptoms. This disease was first described in the cat in England, and cats in the United States are rarely diagnosed with the condition.
  • Tetanus (lockjaw) is an infection with Clostridial bacteria that produce a neurotoxin. These bacteria usually enter the body through a wound of some sort. This neurotoxin causes severe muscle rigidity, seizures and paralysis. The most noticeable ophthalmic (eye) sign is bilateral protrusion of the third eyelids. Fortunately, tetanus is very rare in the cat.

    Systemic causes of protrusion of the third eyelid include the following:

  • Bilateral protrusion of the third eyelids can occur spontaneously in cats and is known as (Haws syndrome). Although the exact cause of Haws syndrome is unknown, it is believed to be related to some mild gastrointestinal problems, such as rotavirus or parasite infestations. These intestinal problems may affect the sympathetic nerves to the eye, resulting in partial or extensive protrusion of the TEs. This condition often resolves spontaneously within 3 to 4 weeks.
  • Tranquilization with certain medications can result in bilateral TE protrusion.
  • Pets with serious physical illnesses may develop TE protrusion from relaxation of the muscles around the eye, or dehydration and weight loss with sinking of the eye deeper into the socket.

    Diseases of the third eyelid that may result in protrusion include the following:

  • Prolapse/protrusion of the tear gland of the TE (also called “cherry eye”) changes the position and shape of the third eyelid.
  • Tumors affecting the TE or gland of the TE, such as lymphoma or squamous cell carcinoma, may result in enlargement and protrusion of the TE.
  • Injury or lacerations of the TE may produce inflammation and swelling of the TE.
  • A foreign body lodged within or behind the TE may cause inflammation, infection and pain, with protrusion of the TE.

    Diseases that cause protrusion of the TE due to ocular pain include the following:

  • Entropion (inward rolling of the eyelids) or abnormal growth of eyelashes causing irritation of the conjunctiva and cornea
  • Corneal ulceration, foreign body, laceration or penetrating injury
  • Injuries to the eyelids and structures around the eye
  • Keratoconjunctivitis sicca (dry eye syndrome) resulting eye discomfort
  • Iritis and anterior uveitis (inflammation of the iris and nearby tissues)
  • Acute glaucoma (sudden elevation in pressure in the eye)
  • Anterior lens luxation (dislocation of the lens into the front chamber of the eye)

    Disorders that affect the size or position of the eye and result in protrusion of the TE include the following:

  • Shrinkage of the eyeball over time from a long-standing, chronic disease within the eye is called phthisis bulbi. As the eyeball shrinks, the TE passively moves upward over the eye.
  • Microphthalmia (congenitally small eye) that is present at birth
  • Severe dehydration or weight loss causing relative shrinkage of the soft tissues behind the eye, resulting in sinking of the eye within the orbit
  • Reduction of orbital fat and muscle related to advanced age or some sort of orbital disease resulting in a deeper-set eye
  • Tumors or cysts growing within the orbit that move the eye and TE forward
  • Abscesses or infections of the soft tissues with swelling within the orbit and forward movement of the eye and TE

 

 

In-depth Information on Diagnosis of Feline Protrusion of Third Eyelid

Diagnostic tests may include one or more of the following:

  • Complete medical history and physical examination
  • Complete ophthalmic examination including testing of pupillary light reflexes, Schirmer tear test, fluorescein staining of the cornea, tonometry to measure the pressure within the eye, and examination of the interior of the eye under magnification. Your veterinarian may refer your cat to a veterinary ophthalmologist for further evaluation using specialized instrumentation.
  • The third eyelid itself may be examined with a forceps after application of a local anesthetic.
  • Neurologic examination to assess the presence of neurologic disease
  • Complete blood count (CBC) and serum biochemistry tests to evaluate the underlying cause and identify any related problems
  • Skull X-rays to determine the presence of a bony orbital or sinus problem
  • Ultrasound examination of the eye and soft tissues within the orbit behind the eye
  • Specialized imaging tests such as computed tomography (CT) scan and magnetic resonance imaging (MRI) of the eye, orbit and brain
  • Pharmacologic testing with topical medications to aid in establishing the diagnosis of Horner’s syndrome and dysautonomia
  • Fine-needle aspirate or biopsy (tissue sample) of abnormal masses/swellings involving the TE and orbit may aid in the diagnosis of a TE tumor or cyst

In-depth Information on Treatment of Feline Protrusion of Third Eyelid

  • Ultimate therapy of TE protrusion depends on identifying the exact cause of the problem. There are numerous possible causes for TE elevation; therefore it is essential to pinpoint a specific cause to provide appropriate treatment.
  • Do not administer human over-the-counter medications, such as Visine® or other ophthalmic remedies intended to “reduce eye redness” or irritation, because these medications rarely help the problem and may make diagnosis of the cause more difficult.

 

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