What does a mobile cyst on the surface of the eye represent and how should it be managed?

Mobile Cyst on Surface of Eye

A mobile cyst on the surface of the eye most likely represents a benign conjunctival inclusion cyst (epithelial cyst), which typically requires no treatment unless symptomatic, at which point simple aspiration or surgical excision with fluid drainage provides definitive management.

What This Represents

A mobile cyst on the conjunctival surface is almost always a conjunctival inclusion cyst (also called epithelial inclusion cyst), which forms when conjunctival or corneal epithelium becomes trapped beneath the surface, creating a fluid-filled cavity 1, 2. These cysts:

• Contain clear or slightly turbid fluid and have an epithelial lining 2, 3
• Are typically benign and asymptomatic 4
• Can occur spontaneously or following ocular surgery (strabismus surgery, cataract surgery) or trauma 1, 2, 5
• Present as translucent, mobile subconjunctival masses that move freely with eye movement 2, 5

Critical Differential Diagnosis to Exclude

Before assuming benign inclusion cyst, you must rule out more serious pathology that can present as conjunctival masses:

Conjunctival lymphoma presents as a painless, pink, fleshy "salmon patch" lesion that is mobile and nonlobulated with intrinsic vessels—this requires systemic workup as up to 20% develop systemic disease 6. Unlike simple cysts, lymphoma appears more solid and salmon-colored rather than translucent.

Ocular surface squamous neoplasia (OSSN) presents with conjunctival hyperemia and papillomatous or sessile nodules that may be leukoplakic or gelatinous, often at the limbus with a sentinel vessel 6, 7. This is a malignancy requiring excision with cryotherapy to edges 7.

When to Observe vs. Treat

Observation is appropriate when:

• The cyst is asymptomatic 4
• No signs of infection (no redness, pain, or purulent material) 4
• Not causing visual obstruction or significant cosmetic concern 2

Treatment is indicated when:

• Foreign body sensation or ocular irritation develops 2
• The cyst becomes infected (redness, pain, purulent contents) 4
• Visual axis obstruction occurs 3
• Patient requests removal for cosmetic reasons 1

Management Algorithm

For Asymptomatic Cysts:

• Reassure the patient of the benign nature 2
• Schedule follow-up only if symptoms develop 4

For Symptomatic or Infected Cysts:

Office-based aspiration (first-line for simple cases):

• Perform aspiration with a 30-gauge needle at the slit lamp 4
• Use bimanual drainage technique to evacuate fluid 4
• If infected, obtain culture swab and prescribe topical antibiotics (tobramycin or moxifloxacin) every 3 hours for one week 4
• Caveat: Simple aspiration alone has higher recurrence rates compared to excision 1

Enhanced office-based treatment (to reduce recurrence):

• After aspiration, inject isopropyl alcohol into the cyst cavity using paired injection technique—this has shown no recurrence at 9 months follow-up 1
• Alternative: intracyst doxycycline injection (though less data available) 1

Surgical excision (definitive treatment):

• Complete cyst excision with fluid aspiration provides definitive cure 2
• Perform in operating room for larger cysts or those not amenable to office treatment 1
• Send tissue for histopathology to confirm epithelial inclusion cyst diagnosis 2
• All patients experience symptomatic relief with no significant recurrence after complete excision 2

Important Pitfalls to Avoid

• Do not mistake for filtering bleb after glaucoma surgery—inclusion cysts can be confused with blebs, but history and location clarify diagnosis 2
• Do not ignore signs of infection—infected inclusion cysts can form conjunctival abscesses requiring immediate drainage and antibiotics 4
• Do not perform simple aspiration without counseling about recurrence—patients should understand that aspiration alone has higher recurrence rates unless combined with sclerosing agents 1
• Do not assume all mobile conjunctival lesions are benign—always examine for features of lymphoma (salmon patch appearance) or OSSN (limbal location, leukoplakia, sentinel vessel) that require different management 6, 7

Follow-up Protocol

• After office-based aspiration or alcohol injection: re-examine at 1 week to confirm resolution and absence of infection 4
• After surgical excision: routine postoperative follow-up with no specific long-term monitoring needed if histopathology confirms benign inclusion cyst 2
• If recurrence occurs after aspiration, proceed to definitive surgical excision 1, 2