Beta blockers have long been a cornerstone in cardiovascular medicine, but their role in eye care—specifically in managing glaucoma—is equally significant. Here, ophthalmologist David Richardson, M.D., explores how these medications function in the eye, shares their risks and side effects, and offers tips on how to use them.  

Mechanism of Action and Dosing Guidelines

Beta blockers work by reducing heart rate and blood pressure, and in the eye, they lower intraocular pressure by decreasing fluid production from the ciliary body. Timolol, Richardson explains, developed as a better-tolerated alternative to earlier topical beta blockers, quickly became the most commonly prescribed option for glaucoma.

Timolol is typically administered in drop form with color-coded caps: yellow for 0.5% and light blue for 0.25% strength. While effective during the day, its usefulness at night is limited, since aqueous fluid production naturally slows during sleep. Initially dosed twice daily, timolol is now often recommended for once-daily use in the morning or early afternoon to minimize systemic effects on blood pressure at night. 

In combination therapies like Cosopt (timolol + carbonic anhydrase inhibitor) and Combigan (timolol + brimonidine), twice-daily dosing may still be required due to the pharmacodynamics of the additional agents.

Systemic and Ocular Side Effects to Consider

When used topically, beta blockers can still cause systemic side effects similar to oral formulations. These include:

• Bradycardia (low heart rate), 
• Hypotension (low blood pressure), and 
• Exacerbation of respiratory issues such as asthma and COPD. 

They are also contraindicated in conditions like congestive heart failure and myasthenia gravis. Moreover, in people with diabetes, beta blockers may mask hypoglycemia symptoms, potentially leading to life-threatening episodes.

Other reported side effects include:

• Local irritation, 
• Eye redness, and 
• Transient blurriness. 

Less commonly, patients may experience mood changes (e.g., depression), fatigue, drowsiness, and even sexual dysfunction. These risks are particularly pronounced in older adults or individuals with pre-existing conditions, making careful patient selection and monitoring essential.

Cost, Access, and Minimizing Side Effects

While generic timolol is typically affordable, Richardson says, branded or preservative-free versions such as Ocudos can be significantly more expensive and are not always covered by insurance. Tools like GoodRx can help identify lower-cost options.

To reduce systemic absorption and side effects, Richardson advises pressing on your tear ducts immediately after putting in the drops. A simpler alternative shown to be effective is using a balled-up tissue placed at the inner eyelid corner. Additionally, he says, using applicators like SimplyTouch allows for smaller, more controlled doses, extending bottle longevity and reducing drug waste.

In general, Richardson says, beta blockers like timolol are a cost-effective and potent glaucoma therapy. When used with attention to dosing, patient-specific risks, and proper drop techniques, they tend to offer efficacy with manageable side effects.

*San Marino Eye | David D. Richardson, MD, Inc. (2020, November 13). Beta Blockers – Glaucoma Medication | Driving with Dr. David Richardson [Video file]. Retrieved from https://www.youtube.com/watch?v=xlB4K30Pg68 

To ensure that we always provide you with high-quality, reliable information, Responsum Health closely vets all sources. We do not, however, endorse or recommend any specific providers, treatments, or products, and the use of a given source does not imply an endorsement of any provider, treatment, medication, procedure, or device discussed within.