The sudden appearance of moisture near your eye as you forcefully clear your nose is a common and often puzzling experience. The simple explanation is that this watery overflow is a direct consequence of the anatomical connection between your eyes and your nasal cavity. This phenomenon is a physical reaction governed by pressure dynamics and the shared drainage system for tears and nasal fluids.
The Anatomy of Tear Drainage
The eye maintains its health by continuously producing a lubricating tear film that must drain away to avoid constant tearing. This drainage process begins near the inner corner of the eye, where two tiny openings called the puncta are located on the upper and lower eyelids. These puncta act like small drains, collecting the tears after they have washed across the eye’s surface.
From the puncta, tears flow into small channels known as the canaliculi, which lead to a larger reservoir called the lacrimal sac. This sac sits in a bony groove near the bridge of the nose and serves as a temporary collecting point for the draining fluid. The lacrimal sac then funnels the fluid down a tube called the nasolacrimal duct.
The nasolacrimal duct is the final segment of this system, extending approximately 12 to 18 millimeters downward and slightly backward into the nose. It opens into the inferior meatus, which is the space beneath the lowest nasal turbinate. This continuous drainage route explains why you often need to wipe your nose when you cry, as the excess tears simply exit through the nasal passages.
The Mechanics of Nasal Pressure
The physical act of blowing your nose involves creating a rapid, positive pressure change within the nasal cavity and the connected air spaces. When you close your mouth and attempt a forced exhalation through the nose, the maximum intranasal pressure generated can be significant, sometimes measuring around 66 millimeters of mercury (mm Hg).
This sudden spike in pressure quickly forces its way backward into any connected channels, including the nasolacrimal duct. At the duct’s opening into the nose sits a mucosal fold known as the Valve of Hasner, which normally functions to prevent the backflow of nasal contents.
However, the powerful pressure from a hard nose blow can easily overcome the resistance of this delicate valve. This reversal of flow forces the fluid—the tears and any mucus collected in the lacrimal sac—back up the drainage pathway. The fluid then exits the system at the point of least resistance, which is the puncta on the surface of the eye, causing the visible overflow of water.
The drainage system is designed primarily for one-way flow, but high pressure allows this reflux to occur easily. The pressure actively pushes the fluid in the wrong direction. The experience of “water coming out of the eye” is a direct and harmless demonstration of the shared plumbing between your nasal and ocular systems.
When to Consult a Doctor About Tear Issues
While watery eyes from blowing your nose are a normal pressure phenomenon, consistent excessive tearing, known medically as epiphora, can signal an underlying issue. If your eyes are perpetually watering, even when you are not actively blowing your nose, this may indicate a partial or complete obstruction in the drainage system.
In adults, this chronic blockage is often termed Primary Acquired Nasolacrimal Duct Obstruction (PANDO), caused by long-term inflammation, fibrosis, or aging. Seek professional advice if you notice a persistent, sticky discharge accompanying the tears.
Yellowish or greenish discharge can be a sign of dacryocystitis, an infection of the lacrimal sac. Other symptoms requiring medical evaluation include swelling, redness, or tenderness near the inner corner of your eye or on the side of your nose. These signs suggest an infection that needs timely attention from an eye care specialist.