Eye drops are liquid solutions formulated for application to the eyes, serving various purposes from providing moisture to delivering medication. These solutions are a common approach for alleviating symptoms such as dryness, redness, or irritation, and for treating numerous eye conditions. Many individuals use them regularly, which often leads to questions about the appropriate amount and frequency of use, particularly whether applying too many eye drops can be detrimental.
How the Eye Handles Drops
The eye has a specific capacity for holding liquid, typically around 7 to 10 microliters in its tear film, which is the natural protective layer on the eye’s surface. However, a single eye drop from a standard dispenser usually ranges from 25 to 50 microliters, a volume significantly larger than the eye can comfortably contain. When a drop is instilled, the excess liquid often spills out onto the eyelids and face.
Beyond the immediate overflow, the eye also possesses a drainage system, the nasolacrimal duct, which carries tears and any applied liquids from the eye’s surface into the nasal cavity and then to the throat. This explains why a person might sometimes taste eye drops after application. This drainage pathway means that any unabsorbed liquid, including the active ingredients of eye drops, can quickly leave the ocular surface.
Understanding “Too Many” Eye Drops
Applying more than a single drop often results in immediate overflow, wasting the product. The eye’s limited capacity means any excess liquid cannot be absorbed or retained. This overflow means additional drops do not deliver more benefit and can dilute the existing tear film.
The implications of “too many” drops vary by type. For lubricating or artificial tears, overuse can paradoxically lead to increased dryness or irritation by washing away natural tear components or disrupting the tear film. Many artificial tears contain preservatives, such as benzalkonium chloride (BAK), which prevent microbial growth. Frequent exposure to these preservatives can cause irritation, burning, stinging, and even damage to the ocular surface, potentially worsening dry eye symptoms.
Medicated eye drops contain active ingredients to treat specific conditions. Applying more than directed can have more serious consequences beyond simple overflow or irritation. The eye’s absorption mechanisms are designed for a specific dosage. Excessive amounts can lead to systemic absorption, where the drug enters the bloodstream and potentially affects other parts of the body.
What Happens When You Overuse
Overusing eye drops can lead to adverse effects, impacting both the eye and the body systemically. Frequent application of artificial tears, especially those with preservatives, can cause increased irritation, stinging, and redness. Some individuals paradoxically experience a worsening of dry eye symptoms due to the disruption of their natural tear film or suppression of natural tear production.
Decongestant eye drops, marketed to reduce eye redness, work by constricting blood vessels. However, prolonged or excessive use of these drops, containing ingredients like tetrahydrozoline or phenylephrine, can lead to a “rebound effect.” This causes blood vessels to become more dilated once the drops wear off, resulting in worse redness and potential dependency. Temporary blurred vision is also a common local side effect.
Beyond local effects, active ingredients in medicated eye drops can be absorbed into the bloodstream through the nasolacrimal duct, potentially reaching significant systemic levels. For instance, phenylephrine eye drops can elevate blood pressure and heart rate, or cause headaches and nervousness. Tetrahydrozoline can also lead to systemic effects such as high blood pressure, increased heart rate, and headaches, with children being particularly sensitive. Brimonidine may cause drowsiness, dizziness, dry mouth, or changes in blood pressure.
Overuse can also mask underlying eye conditions, delaying proper diagnosis and treatment. If symptoms worsen, persist, or if severe pain, vision changes, signs of an allergic reaction, or systemic symptoms occur, seeking medical attention is important.
Proper Application and Safe Use
Proper application of eye drops maximizes effectiveness and reduces adverse effects. Begin by washing your hands thoroughly with soap and water to prevent contamination. Tilt your head back or lie down, then gently pull your lower eyelid down to create a small pocket.
Hold the dropper tip directly over the eye without allowing it to touch your eye, lashes, or any other surface, as this can introduce bacteria and lead to infection. Squeeze the bottle to release a single drop into the created pocket; one drop is sufficient as the eye cannot hold more. After instilling the drop, gently close your eye for a minute or two without blinking excessively. Applying gentle pressure to the inner corner of the eye near the nose for a few minutes can help prevent the medication from draining too quickly, minimizing systemic absorption.
Always adhere to dosage instructions provided by a healthcare professional or on the product label. If you have concerns about eye drop use, consulting an eye care professional or pharmacist is advisable.