The conjunctiva is the thin, clear membrane that covers the white part of the eye and lines the inner surface of the eyelids. This tissue acts as a protective barrier and helps lubricate the eye’s surface with tears and mucus. A conjunctival cyst is a common, typically non-cancerous growth that forms on this membrane. These fluid-filled sacs are generally benign lesions that rarely threaten vision.
What Are Conjunctival Cysts
Conjunctival cysts appear as small, dome-shaped bumps on the surface of the eye. They often present with a clear or translucent appearance because they are filled with fluid. The contents are usually thin and watery, though sometimes the fluid can be slightly turbid or yellowish.
For many people, a small conjunctival cyst causes no sensation and is frequently discovered incidentally during a routine eye examination. When symptoms occur, they commonly involve a foreign body sensation, described as a persistent feeling that something is stuck in the eye. Other mild symptoms include localized irritation, slight redness over the cyst, or discomfort when wearing contact lenses.
It is important to distinguish these cysts from other growths on the conjunctiva, such as pinguecula and pterygium. A pinguecula is a yellowish, slightly raised deposit of protein, fat, or calcium that does not grow onto the cornea. A pterygium is a fleshy, triangular growth that contains blood vessels and is known to invade the cornea, potentially affecting vision.
Why These Cysts Form
The development of conjunctival cysts stems from two primary mechanisms. One common type is the Retention Cyst, which forms when a duct or channel responsible for fluid drainage becomes blocked. This blockage often occurs in the ducts of accessory lacrimal glands or lymphatic channels beneath the conjunctiva, causing normal secretions to become trapped and accumulate.
The second primary category is the Inclusion Cyst, which typically arises following mechanical disruption or trauma to the eye’s surface. This can include previous eye surgery, a blunt injury, or chronic eye rubbing. In these cases, a small fragment of surface epithelial tissue is pushed beneath the conjunctiva. This tissue continues to secrete fluid and mucus, leading to the formation of a cyst wall lined with epithelial cells.
Chronic inflammation is a significant contributing factor that can trigger the formation of either type of cyst. Conditions like chronic allergic conjunctivitis, severe dry eye disease, or prolonged irritation from poor-fitting contact lenses create a persistent inflammatory environment. This ongoing irritation can lead to the epithelial changes or duct blockages that ultimately result in cyst development.
Diagnosis and Treatment
Identifying a conjunctival cyst is usually straightforward and begins with a comprehensive eye examination by an ophthalmologist. The primary diagnostic tool is the slit-lamp biomicroscope, which allows the specialist to view the cyst under high magnification. This detailed visualization confirms the cyst’s translucent, fluid-filled nature, its precise location, and its size.
Management is determined by the size of the lesion and the severity of the symptoms. For small, asymptomatic cysts, a conservative approach of observation is most often recommended. Many of these cysts may resolve spontaneously over weeks or months without intervention. The eye doctor monitors the cyst during regular check-ups to ensure it does not grow or become symptomatic.
If a cyst is large or causing significant foreign body sensation or irritation, a more active treatment may be considered. Simple drainage or aspiration involves puncturing the cyst wall with a fine needle to release the trapped fluid, offering immediate relief. However, because the inner lining of the cyst is often secretory, the cyst sac remains. This makes recurrence of fluid accumulation a common issue after aspiration.
For cysts that are recurrent, large, or highly symptomatic, surgical excision is considered the definitive treatment. This minor outpatient procedure involves the removal of the entire cyst wall, not just the fluid. Removing the wall prevents the lining from continuing to secrete fluid and causing the cyst to return. The prognosis following complete excision is excellent, and the recovery period is typically quick with no long-term impact on vision.