Glaucoma Medications: Prostaglandins vs Beta Blockers and What You Need to Know About Safety

When you're diagnosed with glaucoma, your doctor will likely recommend one of two main types of eye drops: prostaglandins or beta blockers. Both lower eye pressure-the main goal in stopping glaucoma from damaging your vision-but they work in very different ways, and their side effects can change your life in ways you might not expect.

How Prostaglandins Lower Eye Pressure

Prostaglandin analogs like latanoprost, bimatoprost, and travoprost don’t just reduce fluid in the eye-they change how it drains. These medications activate receptors in the eye’s drainage system, opening up new pathways for fluid to escape. This is called uveoscleral outflow. The result? A 24% to 33% drop in eye pressure, often more than any other class of glaucoma drug.

What makes prostaglandins popular isn’t just their power-it’s how easy they are to take. One drop, once a day, usually at night. No reminders. No complicated schedules. That’s why they’re the top first-choice treatment in most clinics today. A 2019 study found that 39% of people stayed on prostaglandins after a year, compared to just 25% on beta blockers.

But there’s a catch. These drops cause real, lasting changes to your eyes. About 5% to 10% of long-term users develop darker iris color-especially if they have hazel or green eyes. Eyelashes get longer, thicker, and darker. Some people like this side effect. Others find it unsettling. And while it’s not dangerous, it’s permanent. Once it happens, it doesn’t go away when you stop the drops.

Another common issue: red eyes. Up to half of users notice redness or bloodshot appearance. It’s usually mild and fades during the day, but it can make people self-conscious. Bimatoprost causes more redness and irritation than latanoprost. About 25% to 30% of bimatoprost users report burning or stinging, compared to 15% to 20% with latanoprost. That’s why many doctors start with latanoprost unless there’s a reason to choose otherwise.

How Beta Blockers Work-and Their Hidden Risks

Beta blockers like timolol and betaxolol work differently. Instead of helping fluid drain, they slow down how much fluid your eye makes. They block beta receptors in the ciliary body, the part of the eye that produces aqueous humor. This reduces pressure by about 20% to 25%-slightly less than prostaglandins, but still effective.

Here’s the problem: beta blockers aren’t just local. They get absorbed into your bloodstream. That means they can affect your heart and lungs. If you have asthma, COPD, or a slow heart rate, these drops can be dangerous. They’ve been linked to breathing trouble, fatigue, dizziness, and even heart failure in high-risk patients. The FDA requires a black box warning on timolol for these reasons.

Another downside: you have to use them twice a day. That cuts into adherence. Studies show people forget or skip doses more often with twice-daily meds. One study found that people on beta blockers were 60% more likely to stop taking their drops within a year than those on prostaglandins.

Betaxolol, a selective beta blocker, may be safer for people with mild lung issues because it’s less likely to affect the airways. Some early data suggested it might protect vision better in the first six months than timolol, but that hasn’t held up in longer studies. Still, for patients who can’t use prostaglandins, betaxolol is often the go-to beta blocker.

Which Is Safer? It Depends on You

Safety isn’t just about side effects-it’s about who you are.

If you have asthma, COPD, heart disease, or depression, beta blockers are risky. Even if you’ve never had symptoms, your doctor should check your medical history before prescribing them. If you’re over 65, have diabetes, or take other heart meds, the risk goes up.

If you’re young, healthy, and don’t mind cosmetic changes, prostaglandins are usually the better pick. But if you’re concerned about darkening irises or thickening lashes, or if you work in a job where red eyes are frowned upon (like customer service or photography), you might want to avoid them.

There’s no one-size-fits-all answer. A 2013 seven-year study comparing the two classes found no difference in how well they protected vision. Both kept the visual field stable over time. That means the choice isn’t about which one works better-it’s about which one you can stick with.

Combining Medications: More Isn’t Always Better

Many people end up on more than one drop. If one medication doesn’t lower pressure enough, doctors often add another. Combining a prostaglandin with a beta blocker like timolol can drop pressure an extra 13% to 25%-better than either alone.

But here’s the twist: mixing two prostaglandins (like latanoprost and bimatoprost) can actually raise eye pressure. That’s not a mistake-it’s a known risk. Studies show this combo can make glaucoma worse. Don’t ever do it.

Fixed-dose combinations (like latanoprost/timolol in one bottle) exist to simplify routines. But they’re not always better. A 2005 study found no clear advantage in pressure control over using the drops separately. The real benefit? Fewer bottles, fewer drops, fewer chances to forget.

Preservative-Free Drops: Worth the Extra Cost?

Most glaucoma drops contain benzalkonium chloride (BAK), a preservative that kills bacteria but also damages the eye’s surface over time. Long-term users often develop dry eyes, burning, and irritation.

Preservative-free versions are available for both prostaglandins and beta blockers. A 2021 review of seven studies found they improved tear film quality and reduced dryness. But here’s the catch: they lowered eye pressure by only 0.29 mmHg more than preserved drops-so little that it’s not clinically meaningful.

So why do they cost 20% to 25% more? Because they’re single-use vials. You throw them away after one use. Hospitals and large clinics are starting to use them for long-term patients, especially those with dry eye or contact lens wearers. But for most people, the benefit doesn’t justify the price.

What to Expect When You Start

When you begin either type of drop, your doctor will likely ask you to come back in 4 to 6 weeks. That’s to check your eye pressure and ask about side effects.

Here’s what to watch for:

• Prostaglandins: Red eyes, longer lashes, darker iris color, occasional stinging. These usually start within days or weeks.
• Beta blockers: Fatigue, dizziness, shortness of breath, slow heartbeat, cold hands or feet. These can show up anytime, even months later.

If you notice any of these, don’t stop the drops. Call your doctor. Some side effects can be managed with different timing, different drops, or even switching classes.

Proper technique matters too. Tilt your head back, pull down your lower lid, drop it in, close your eye, and press gently on the inner corner of your eye for a minute. This keeps the medicine from draining into your nose and getting absorbed into your bloodstream-especially important with beta blockers.

Long-Term Outlook: What’s Next?

Glaucoma is a lifelong condition. Medications won’t cure it, but they can stop it from getting worse. For now, prostaglandins are the standard first step for most people. Beta blockers are still used, but mostly when prostaglandins aren’t right-because of cost, side effects, or medical history.

Research is moving toward new delivery systems: slow-release implants, contact lenses that release medicine, and even pills with fewer side effects. But for now, eye drops remain the backbone of treatment.

The best choice isn’t the one with the lowest pressure number. It’s the one you can use every day without fear, discomfort, or confusion. That’s the real measure of success.