The lacrimal sac is a small reservoir located at the inner corner of the eye, functioning as part of the body’s natural tear drainage system. Tears collect here before draining into the nasal cavity. Air in this structure, sometimes called lacrimal pneumatocele, occurs when air travels backward against the normal flow of tears. This can result in noticeable symptoms, such as a squishing or bubbling sensation when pressure is applied near the nose. Understanding the anatomy and the forces causing this reverse flow is key to finding relief.
The Lacrimal System and Air Entry
The lacrimal system is a series of delicate channels designed to move tears from the eye into the nose, maintaining a clean and lubricated ocular surface. Tears first enter two tiny openings called puncta, one on the upper eyelid and one on the lower eyelid, located near the nose. From the puncta, tears drain into the canaliculi, which are small tubes that converge and empty into the lacrimal sac.
The lacrimal sac is the dilated upper portion of the nasolacrimal duct, the main channel that descends through a bony canal into the nasal cavity. At the terminal end of the nasolacrimal duct, where it opens into the nose, there is a mucosal fold known as the valve of Hasner. This valve normally acts as a one-way gate, allowing tears to pass into the nose but preventing air and nasal contents from traveling backward up the duct.
Air enters the lacrimal sac when a pressure differential allows reverse flow from the nasal cavity. This happens when the pressure inside the nose is significantly higher than the pressure in the lacrimal sac. If the valve of Hasner is weak or absent, high nasal pressure can force air up the nasolacrimal duct and into the sac. The resulting air pocket expands the sac, causing the characteristic sensation and sometimes visible swelling at the inner corner of the eye.
Common Causes of Air Trapping
Air trapping in the lacrimal sac is often triggered by sudden, high-pressure events that overwhelm the nasolacrimal system’s normal defenses. The most common cause involves forceful maneuvers that increase pressure within the nasal cavity and sinuses. Vigorous nose blowing, severe coughing fits, or a forceful sneeze can generate enough back pressure to push air past the valve of Hasner and into the sac.
Another significant cause is the disruption of the bony or soft tissue structures that surround the lacrimal system. Trauma to the face, such as an orbital or nasal bone fracture, can create an abnormal communication between the air-filled sinuses and the lacrimal sac. This new pathway allows air to leak directly into the sac, bypassing the duct entirely.
Prior surgical procedures involving the nasal cavity or sinuses may also inadvertently lead to air entry. Procedures like endoscopic sinus surgery or dacryocystorhinostomy (DCR) can sometimes damage the delicate lining or alter the surrounding pressure dynamics. Patients using Continuous Positive Airway Pressure (CPAP) machines for sleep apnea may experience air regurgitation, as the pressurized air from the mask can be forced into the tear duct system. Partial blockages or stenosis within the nasolacrimal duct can also contribute by creating a pressure imbalance that favors the reverse movement of air.
Managing Air in the Lacrimal Sac
For transient air trapped in the lacrimal sac, the first step in management involves simple, gentle home care techniques. Applying a very light, downward massage over the lacrimal sac—located just below the inner corner of the eye—can help encourage the air to pass down the nasolacrimal duct and into the nose. This massage should be performed with a clean finger or a cotton swab, moving from the bony ridge near the eye toward the side of the nose.
Concurrently, it is helpful to avoid activities that induce high nasal pressure, such as forcefully blowing the nose. Using a warm, moist compress over the area may also be beneficial, as it can reduce any accompanying swelling and loosen minor debris that might be contributing to a temporary blockage. While these methods may relieve transient air, persistent or recurrent air trapping requires professional attention.
A persistent air pocket or signs of infection, such as redness, pain, or significant swelling, necessitate an evaluation by an ophthalmologist or ear, nose, and throat (ENT) specialist. The physician may use diagnostic methods like a dye disappearance test or a computed tomography (CT) scan to visualize the lacrimal system and identify any underlying structural issues. If a blockage is confirmed, treatment options may include probing and irrigation of the duct to relieve pressure and clear the passageway.
For chronic or severe cases, especially those linked to structural defects or recurrent infection, a surgical solution may be proposed. Dacryocystorhinostomy (DCR) is a procedure that creates a new, wider opening between the lacrimal sac and the nasal cavity, permanently bypassing any blockage or non-functional valve. Where air entry is a complication of CPAP use, the physician may recommend adjustments to the mask type, such as switching to a total face mask, or using devices like a punctal plug to physically prevent air from entering the system.