How Eye Drops Reach the Throat
The eye has a sophisticated drainage system that can inadvertently transport eye drops into the throat. This pathway begins with two small openings located at the inner corner of each eye, near the nose, known as the lacrimal puncta. These puncta lead into tiny tubes called the canaliculi, which are approximately 10 millimeters long.
The canaliculi then merge to form a common canaliculus, which empties into the lacrimal sac. This sac, situated within a bony depression on the side of the nose, collects the fluid.
From the lacrimal sac, the liquid flows down the nasolacrimal duct. This nasolacrimal duct descends through a bone channel into the nasal cavity. Once in the nasal cavity, the liquid can then drain down the back of the throat.
Therefore, when eye drops are instilled, any excess liquid that does not remain on the eye’s surface or evaporate will follow this anatomical route, eventually reaching the throat.
Why Eye Drops Can Cause Throat Irritation
The sensation of throat irritation after using eye drops often stems from the chemical properties of the drops themselves. Many eye drop formulations contain preservatives, with benzalkonium chloride (BAK) being a common example. BAK is used to prevent microbial contamination. However, when it reaches the delicate mucous membranes of the throat, it can cause a drying or irritating sensation.
Beyond preservatives, the active medicinal ingredients in some eye drops can also contribute to this irritation. For instance, certain glaucoma medications or allergy drops may have a bitter taste or a chemical composition that, upon contact with the throat, triggers a mild inflammatory response or an unpleasant sensation.
The pH level of eye drops is another factor, as solutions that are significantly more acidic or alkaline than the body’s natural pH can cause discomfort to sensitive tissues.
The volume of eye drops instilled can further influence throat irritation. A standard eye drop is about 50 microliters, while the eye can hold only about 7-10 microliters of fluid. This means a substantial portion of the drop often drains through the lacrimal system, increasing the likelihood of it reaching the throat. Individual sensitivity also plays a role, as some people’s mucous membranes are more reactive.
When to Be Concerned
While a mild, temporary sensation in the throat after using eye drops is a recognized occurrence, certain symptoms warrant closer attention. If throat irritation persists beyond an hour or worsens, it may indicate a significant issue. Persistent soreness, a constant lump in the throat, or unresolved difficulty swallowing should prompt consultation with a healthcare professional.
Other concerning signs include a worsening cough, especially if chronic or productive. Swelling of the throat, tongue, or lips, or a rash/hives, could signal an allergic reaction. Though rare, severe allergic responses like anaphylaxis involve rapid onset of breathing difficulties, dizziness, and a drop in blood pressure, requiring immediate emergency care.
It is important to differentiate between common irritation and symptoms suggesting an adverse reaction or underlying medical condition. If throat discomfort accompanies voice changes, fever, or a worsening eye condition, seek medical advice. A healthcare provider can assess the situation, determine the cause, and suggest management or alternative treatments.
Minimizing Throat Irritation
Several techniques can help reduce eye drop solution that drains into the throat, minimizing irritation. One effective method is nasolacrimal occlusion: applying gentle pressure to the inner corner of the eye, near the nose, immediately after instilling drops. Maintain this pressure for one to two minutes. This temporarily closes the lacrimal puncta, preventing drops from entering the tear drainage system and reaching the throat.
Proper instillation technique also reduces overflow. Tilt the head slightly backward and pull the lower eyelid down to create a pocket, ensuring the drop lands directly on the eye’s surface. After instilling, gently close the eye for a minute or two, rather than blinking excessively. This allows the solution to spread and absorb, reducing drainage.
Discussing alternative eye drop formulations with a healthcare provider can be beneficial for those with consistent throat irritation. Preservative-free eye drops are available for many common conditions, eliminating chemicals like benzalkonium chloride often implicated in irritation. Exploring different active ingredients or lower concentrations might also be an option if the active compound is the primary irritant.