Overview: What is Cherry Eye and Why Does it Matter?

Cherry eye, medically known as prolapse of the nictitating membrane gland or adenoma of the third eyelid gland, is a common condition seen in both dogs and cats, though it is far more prevalent in dogs. The "cherry" appearance refers to a pinkish-red, cherry-like mass that protrudes from the inner corner of the eye (the nasal side). This mass is actually the lacrimal gland of the third eyelid, which has become dislodged from its normal position.

The third eyelid, or nictitating membrane, is a protective, transparent or semi-transparent membrane that sweeps across the eye from the nasal side to the temporal side. It helps to lubricate the eye, remove debris, and provide additional protection. The gland within this third eyelid produces a significant portion of the eye's tear film, contributing to ocular lubrication and health. When this gland prolapses, it can interfere with vision, become irritated, dry out, and be susceptible to secondary infections. Left untreated, chronic irritation and exposure can lead to discomfort, pain, and potentially more severe eye complications, including keratitis (inflammation of the cornea) and even dry eye syndrome (keratoconjunctivitis sicca) later in life, as the damaged gland may lose its ability to produce adequate tears.

Early recognition and appropriate surgical intervention are crucial to restore normal function, alleviate discomfort, and prevent long-term damage to the eye.

Causes and Risk Factors

While the exact cause of cherry eye can sometimes be elusive, it is generally believed to be a developmental or hereditary defect in the connective tissue that anchors the gland to its normal position within the third eyelid. This weakness allows the gland to prolapse.

Breed Predisposition: Certain breeds are genetically predisposed to developing cherry eye. In dogs, these include breeds like the Cocker Spaniel (both American and English), Cavalier King Charles Spaniel, Beagle, Boston Terrier, Bulldog, Basset Hound, and Shih Tzu. While less common, cats can also develop cherry eye, with breeds like the Persian and Burmese showing a higher incidence.

Age: Cherry eye most commonly occurs in young animals, typically between 6 months and 2 years of age, during their rapid growth phases.

Genetics: As mentioned, a hereditary component is strongly suspected due to the breed predispositions. If a pet's parents or close relatives have experienced cherry eye, they may be at a higher risk.

Trauma: Although less common than developmental causes, direct trauma to the eye or blunt force to the head can occasionally lead to the gland prolapsing.

Other Factors: Some sources suggest that inflammation within the eye might play a role in weakening the supporting tissues, but this is less clearly defined as a primary cause.

Signs and Symptoms

Pet owners should be vigilant for the following signs, which often indicate the presence of cherry eye:

• Visible Red Mass: The most obvious sign is a fleshy, red or pinkish mass protruding from the inner corner of the affected eye. It may resemble a cherry, hence the common name.
• Eye Redness and Inflammation: The conjunctiva (the pink tissue around the eye) may appear red, swollen, and irritated.
• Excessive Tearing (Epiphora): The prolapsed gland can disrupt normal tear drainage and production, leading to watery eyes.
• Discharge: A sticky, mucoid, or pus-like discharge may be present, which can sometimes be mistaken for signs of gastritis or other systemic issues if not observed in the eye.
• Squinting (Blepharospasm): Pets may squint or hold the affected eye partially or fully closed due to discomfort or irritation.
• Rubbing or Pawing at the Eye: The pet may repeatedly try to rub the affected eye with its paw or on furniture.
• Dry Eye Symptoms: In some cases, the prolapsed gland may also be associated with reduced tear production, leading to symptoms of dry eye, such as a dull cornea, sticky discharge, and persistent irritation. This can sometimes lead to a cycle of inflammation and discomfort, similar to how chronic conditions can impact other bodily systems.
• Foreign Body Sensation: The pet may act as if something is in its eye, blinking frequently or showing a general sense of unease regarding the affected eye.

It is important to note that cherry eye can affect one eye (unilateral) or both eyes (bilateral), sometimes occurring simultaneously or sequentially.

Diagnosis

Diagnosing cherry eye is typically straightforward for a veterinarian. The characteristic appearance of the prolapsed gland makes it easily identifiable during a physical examination.

1. Physical Examination: The veterinarian will carefully examine the pet's eye, looking for the telltale red mass. They will assess the size and location of the prolapse, as well as the overall health of the eye, including the cornea and conjunctiva.
2. Ocular Examination: A thorough ocular exam is performed to rule out other conditions and assess the extent of any secondary complications. This may involve:

• Schirmer Tear Test: This test measures tear production. While cherry eye itself doesn't directly cause dry eye, the damaged gland might lead to reduced tear production over time, or a concurrent condition could exist. A low tear production reading warrants further investigation and may influence treatment decisions, as discussed in comprehensive veterinary ophthalmology resources (Merck Veterinary Manual).

• Fluorescein Stain: This dye is used to detect corneal ulcers or abrasions. The prolapsed gland can cause corneal irritation, making it prone to scratches.

• Intraocular Pressure Measurement: Tonometry may be performed to check for glaucoma, although it is not directly related to cherry eye.

3. History Taking: The veterinarian will ask about the onset of symptoms, any previous eye issues, and the pet's breed and age, as these factors can aid in diagnosis and understanding potential underlying causes.

In most cases, the diagnosis is confirmed visually. The primary goal of the diagnostic process is to determine the best course of treatment and identify any concurrent eye conditions.

Treatment and Management

The standard and most effective treatment for cherry eye is surgical repositioning of the prolapsed gland. While medical management (like topical medications) might be used temporarily to control inflammation or secondary infections, it does not correct the underlying anatomical problem and is generally not a long-term solution.

Surgical Repositioning (The "Pocket" or "Tie-Over" Technique)

The goal of surgery is to return the gland to its normal anatomical location and secure it there, rather than simply removing it. Removal of the gland is strongly discouraged because it produces a significant portion (estimated between 30-50%) of the eye's tear film (Merck Veterinary Manual). Excision of the gland can lead to chronic dry eye (KCS), which requires lifelong management with eye drops like cyclosporine or esomeprazole for lubrication and inflammation control, and can be more costly and burdensome in the long run.

The most common surgical techniques involve creating a "pocket" in the tissue of the third eyelid and tucking the prolapsed gland back into this pocket. Sutures are then used to hold the gland in place. Alternatively, a "tie-over" technique may be employed where sutures pass through the gland and are tied over the surface of the third eyelid cartilage.

Surgical Procedure:

• The surgery is typically performed under general anesthesia.
• The veterinarian will carefully reposition the prolapsed gland.
• Sutures are used to secure the gland in its correct anatomical position.
• The procedure is usually completed within 30-60 minutes.

Medical Management (Adjunctive or Temporary)

In some cases, particularly if there is significant inflammation or secondary infection, the veterinarian may prescribe:

• Topical Antibiotic/Steroid Eye Drops or Ointments: These help to reduce inflammation and treat any infection present before or after surgery. Examples might include formulations containing antibiotics and anti-inflammatory agents. Overuse of steroids should be avoided, as per veterinary guidance.
• Artificial Tears: To provide lubrication and comfort during the healing process or if tear production is compromised.

Considerations for Bilateral Cases

If both eyes are affected, the veterinarian may recommend operating on one eye at a time, with a waiting period of a few weeks between surgeries. This allows the pet to maintain some vision and comfort during recovery from the first surgery and reduces the risk of complications affecting both eyes simultaneously. However, in some stable patients, simultaneous surgery may be considered.

Recovery and Aftercare

Proper post-operative care is vital for a successful recovery. Following your veterinarian's instructions closely will help minimize complications and ensure the gland heals in its proper position.

• Elizabethan Collar (Cone): Your pet will likely need to wear an Elizabethan Collar (Cone) continuously for 7-14 days to prevent them from rubbing or scratching at the surgical site. This is crucial to prevent suture tearing or further irritation.
• Medications: Administer all prescribed eye drops and medications exactly as directed by your veterinarian. This typically includes antibiotic and anti-inflammatory drops for a specified period.
• Activity Restriction: Limit your pet's activity for the first 1-2 weeks. Avoid rough play, jumping, or any strenuous activities that could put stress on the surgical site or cause injury.
• Monitoring the Surgical Site: Gently check the eye daily for any signs of excessive swelling, redness, discharge, or pain. A small amount of mild swelling or redness immediately after surgery is normal, but significant worsening should be reported to your vet.
• Bathing: Avoid bathing your pet during the initial recovery period, or take extreme care to keep the eye area completely dry.
• Follow-Up Appointments: Attend all scheduled follow-up appointments. The veterinarian will check the healing progress, remove sutures if necessary, and assess the gland's position.
• Diet: Maintain your pet's normal diet unless otherwise instructed. Ensure access to fresh water. If your pet has a history of digestive upset, like constipation or cobalamin (B12) deficiency, maintain their management plan, but inform your vet of the eye surgery.

Most pets recover well from cherry eye surgery with proper care. The success rate is generally high, especially when the gland is repositioned rather than removed.

Cost Considerations

The cost of cherry eye repair can vary significantly depending on several factors:

• Veterinary Clinic: Costs differ between general practices and veterinary specialty hospitals (ophthalmologists).
• Geographic Location: Prices may be higher in metropolitan areas compared to rural regions.
• Severity of the Condition: If the condition is bilateral or if there are complications requiring additional procedures or longer anesthesia times, the cost will increase.
• Anesthesia: The type of anesthesia used and monitoring during anesthesia contribute to the overall cost.
• Pre-operative and Post-operative Medications: The cost of prescribed eye drops, ointments, and pain medication is additional.
• Follow-up Visits: Post-operative rechecks are necessary and will incur additional fees.

General Estimate: For a single eye, the cost can range from approximately $300 to $1,500 or more. If both eyes require surgery, the total cost will be roughly double, though sometimes there might be a slight discount for a bilateral procedure performed simultaneously.

It is always recommended to obtain a detailed estimate from your veterinarian before proceeding with surgery. Pet insurance may cover a portion of these costs, depending on the policy's terms.

When to Contact a Vet

It is crucial to contact your veterinarian immediately if you notice any of the following:

• Sudden appearance of a red, cherry-like mass in the eye.
• Signs of pain or discomfort: excessive squinting, pawing at the eye, reluctance to eat or interact.
• Increased eye redness, swelling, or irritation.
• Changes in eye discharge: becoming thicker, more colored (yellow/green), or more abundant.
• Cloudiness or changes in the appearance of the cornea (the clear front surface of the eye).
• Decreased vision or apparent blindness.
• Any signs of infection or complications after surgery: increased swelling, heat, pus, or suture breakdown.
• Your pet is rubbing, scratching, or chewing at the Elizabethan Collar (Cone) or surgical site.

Early veterinary attention is key to a positive outcome for cherry eye. Prompt diagnosis and surgical intervention can prevent chronic discomfort and long-term eye damage, ensuring your pet maintains comfortable and healthy vision. Conditions like severe eye inflammation or trauma, which could resemble or exacerbate cherry eye, require immediate professional assessment, just as other acute issues like a spider bite or a degloving injury would.