What Happens If You Put Too Many Glaucoma Eye Drops In?

A single eye drop contains more medication than your eye can absorb, with the excess running down the cheek or into your tear duct. This means intentionally using too many glaucoma eye drops does not increase effectiveness and can instead heighten the risk of adverse effects.

Quick Summary

Using more glaucoma eye drops than prescribed won't boost efficacy but can cause localized side effects and increase the risk of systemic absorption. Risks vary by medication class, from irritation to cardiovascular issues. Proper instillation technique is key to avoiding overuse and minimizing adverse effects.

Key Points

• One Drop Is Enough: The eye cannot hold more than one drop of medication, and any excess will simply be wasted or absorbed systemically.

• Systemic Absorption is a Risk: Overusing eye drops increases the chance of medication being absorbed into the bloodstream through the nasal passage, potentially causing systemic side effects.

• Side Effects Vary by Drug Class: Different types of glaucoma medications, like beta-blockers or prostaglandin analogs, carry distinct risks for side effects if overused.

• Practice Proper Technique: To prevent overuse, practice correct eye drop instillation, including applying one drop at a time and performing punctal occlusion.

• Know When to Act: If you experience severe systemic symptoms after using too many drops, contact your doctor immediately, but for mild irritation, rinsing the eye is often sufficient.

The Science of Ocular Absorption

When you administer eye drops, the surface of your eye can only hold a very small amount of liquid. The volume of a single drop from a standard eye drop bottle is significantly larger than what the eye can physically contain. Any extra medication immediately overflows onto the cheek or drains through the puncta (tear duct openings) located in the inner corner of your eyelids.

This drainage pathway leads directly to the nasal and throat passages, where the medication can be absorbed into the bloodstream. This process, known as systemic absorption, is the primary reason why using too many drops can lead to side effects in other parts of the body, even though the medication was only applied topically.

Potential Consequences of Excessive Drops

Using more than one drop at a time does not provide any additional therapeutic benefit for lowering intraocular pressure (IOP), and in fact, it can lead to several problems:

• Increased Local Side Effects: The excess medication can irritate the surface of the eye, causing increased redness, stinging, and a watery sensation. For some, this can worsen over time and lead to a worsening of ocular surface disease.
• Enhanced Systemic Absorption and Side Effects: With more medication draining into the nasal passages, the likelihood of systemic side effects increases. These can vary widely depending on the drug class. For instance, beta-blockers can cause a slower heart rate and breathing problems, while carbonic anhydrase inhibitors can lead to tingling and stomach upset.
• Wasting Medication: Given that a single drop is sufficient, using multiple drops simply wastes the expensive medication and causes you to run out of your prescription more quickly.
• Inconsistent Dosage: Administering excess drops can disrupt your overall treatment schedule. The most important factor in glaucoma treatment is consistent, regular application to keep IOP stable, not saturating the eye at one time.

Class-Specific Risks with Overuse

While general side effects like irritation are common, the systemic risks of overuse are specific to the class of glaucoma medication being used:

• Beta-blockers (e.g., Timolol): Overuse can lead to a dangerously slow heart rate (bradycardia), lower blood pressure, and potential breathing problems, especially in individuals with asthma or COPD.
• Prostaglandin Analogs (e.g., Latanoprost, Bimatoprost): Excess use can exacerbate local side effects such as eye redness, eyelid darkening, and changes in eyelash growth. Systemic effects are less common but can occur.
• Alpha-adrenergic Agonists (e.g., Brimonidine): Using too many drops increases the risk of systemic side effects like fatigue, dizziness, dry mouth, and an irregular or racing heartbeat.
• Carbonic Anhydrase Inhibitors (e.g., Dorzolamide): With excessive use, you are more likely to experience a metallic taste in the mouth, headaches, and tingling in the hands and feet.

What to Do If You Use Too Many Drops

If you accidentally put too many drops in your eye, follow these steps:

1. Don't Panic: In most cases, mild overuse is not an emergency, but it's important to take the right steps.
2. Blot the Excess: Immediately use a clean tissue to wipe away any excess liquid that has spilled onto your cheek or eyelids.
3. Rinse with Water: If your eye feels irritated or stings, you can gently rinse it with cool, clean water.
4. Perform Punctal Occlusion: Gently press your finger on the inside corner of your eye, next to your nose, for at least one to two minutes. This helps block the tear duct and prevents medication from entering your bloodstream.
5. Monitor for Symptoms: Watch for any unusual or severe side effects. If you experience dizziness, breathing problems, a slow heart rate, or severe irritation, contact your doctor immediately.
6. Contact Your Doctor: When in doubt, especially if you have an underlying health condition, call your ophthalmologist or general practitioner for advice.

Proper Instillation Techniques to Prevent Overuse

Preventing overuse is as simple as perfecting your eye drop technique. Correct application ensures the right amount of medication is absorbed and reduces the risk of side effects.

Steps for Correct Eye Drop Application:

1. Wash your hands thoroughly to prevent contamination.
2. Tilt your head back and gently pull your lower eyelid down to form a small pocket.
3. Administer just one drop into the pocket. Do not touch the tip of the bottle to your eye or lashes.
4. Close your eyes and press your finger lightly on the inner corner of your eye for at least one minute.
5. Blot any excess liquid from your cheek with a clean tissue.

Comparison of Risks from Over-application by Medication Class

Medication Class	Primary Action	Common Side Effects of Overuse (Systemic)	Local Side Effects of Overuse	What to Do Immediately
Beta-blockers	Reduces fluid production	Slow heart rate, low blood pressure, breathing difficulty	Stinging, redness	Use punctal occlusion; contact doctor for severe symptoms.
Prostaglandin Analogs	Increases fluid outflow	Minimal systemic effects noted	Increased eye redness, eyelid/iris darkening	Wipe away excess; rinse if irritated.
Alpha-adrenergic Agonists	Reduces fluid production & increases outflow	Fatigue, dry mouth, irregular heart rate	Red, itchy, or swollen eyes	Wipe excess; contact doctor for severe systemic symptoms.
Carbonic Anhydrase Inhibitors	Reduces fluid production	Metallic taste, tingling, nausea, headache	Stinging, redness	Wipe away excess; rinse if irritated; contact doctor for severe symptoms.

Conclusion

While a single, accidental extra drop of glaucoma medication is unlikely to cause serious harm, consistently using too many eye drops is a common and preventable mistake that carries unnecessary risks. The eye can only absorb so much medication, and over-application primarily increases the likelihood of systemic absorption and side effects. By learning and practicing the correct instillation technique, patients can ensure they receive the full benefit of their medication while minimizing waste and protecting their overall health. Consistency and precision are far more important than quantity when it comes to managing glaucoma effectively.

For more information on managing glaucoma and its medications, consult the Glaucoma Research Foundation website.

Frequently Asked Questions

Will an extra drop of glaucoma medication hurt my eye?

A single extra drop is unlikely to cause serious harm to your eye, but it can increase local side effects like redness and stinging. The key is to avoid consistent overuse.

What is the primary risk of using too many glaucoma drops?

The primary risk is the increased likelihood of systemic side effects, which occur when excess medication drains into your nasal passages and is absorbed into the bloodstream.

Can I overdose on glaucoma eye drops?

While a fatal overdose is highly unlikely, it is possible to experience an overdose of a specific drug's active ingredients, leading to pronounced and potentially dangerous systemic side effects.

What happens if I put in an extra beta-blocker drop?

Using too much of a beta-blocker can cause a slower heart rate, lower blood pressure, and breathing difficulties, especially in patients with pre-existing heart or respiratory conditions.

Does using more drops lower my eye pressure faster?

No, using more drops does not lower eye pressure faster or more effectively. A single drop is the optimal dose, and any extra is simply a waste of medication.

What should I do if I accidentally put in two drops and then remember?

Simply blot away the excess liquid and perform punctal occlusion by pressing the inner corner of your eye. Do not instill any more medication until your next scheduled dose.

Why do my eyes feel irritated after using too many drops?

Over-application can cause the excess medication and its preservatives to pool on the ocular surface, leading to increased irritation, stinging, and redness.