Starting a glaucoma eye drop is a significant moment. You have been told you have a condition that can steal your vision silently, and you are holding a small bottle that is supposed to prevent that. You have questions. In this article, Dr Shibal Bhartiya answers these questions: how the drops work, what each class does, how to use them correctly, why so many eye drops, what the side effects actually mean, and what happens if the drops are not enough.
Dr Shibal Bhartiya is a fellowship-trained glaucoma specialist and Mayo Clinic Research Collaborator with over 25 years of experience. Her approach focuses on identifying risk before damage is irreversible, simplifying treatment decisions, and protecting vision long-term.
Why Eye Drops Are the First Treatment for Glaucoma
Glaucoma damages the optic nerve — the cable that carries visual information from the eye to the brain. In most cases, raised intraocular pressure (IOP) is the driver of that damage. Lowering IOP is currently the only proven way to slow or stop glaucoma progression.
Eye drops lower IOP by one of two mechanisms: reducing the amount of fluid (aqueous humour) produced inside the eye, or improving the drainage of that fluid out of the eye. They do not cure glaucoma. They control it — reliably and safely — for as long as you use them. When drops are discontinued, pressure returns.
Laser and surgical treatment are also effective options. Your doctor will discuss which approach suits your type of glaucoma, your pressure level, your lifestyle, and your overall health. For most patients with open-angle glaucoma, drops are the appropriate starting point. Slowly, SLT is gaining first place.
What Is Target IOP — and Why It Matters for Your Drops
Before prescribing drops, your glaucoma specialist sets a target IOP — the pressure level at which your optic nerve is unlikely to suffer further damage. This is individual. It depends on your baseline pressure, the extent of existing nerve damage, your age, and other risk factors.
The goal of your drops is to reach and maintain that target. If the first drop achieves it, no further medication is added. If it does not, a second drop is added — either separately or as a fixed dose combination. This is not a failure. It is how glaucoma medicine works.
You can read one of my research papers on this topic, indexed on Pubmed, on New perspectives on target intraocular pressure , which I co-authored with my colleagues from Sydney Eye Hospital, Sydney, Australia; The University of Sydney, Sydney, Australia; and Department of Clinical Neurosciences, University of Geneva, Switzerland.
Classes of Glaucoma Eye Drops
Prostaglandin Analogues — First-Line Treatment
Prostaglandin analogues are the first choice for most patients with open-angle glaucoma. They are used once daily — usually at night — and provide the strongest 24-hour IOP lowering of any single drop class, typically reducing pressure by 25 to 35 percent.
They work by increasing the uveoscleral outflow of aqueous humour — opening an alternative drainage pathway that bypasses the trabecular meshwork.
Drugs in this class: Latanoprost (Xalatan), Bimatoprost (Lumigan), Travoprost (Travatan), Tafluprost, and Latanoprostene bunod — a newer formulation that also releases nitric oxide to further enhance drainage.
Side effects to know:
Local side effects are common and worth discussing with your doctor before you start. They include redness and a mild burning sensation on instillation, lengthening and darkening of eyelashes, and — with long-term use — a gradual darkening of the iris pigmentation, particularly in eyes that are blue, green, or hazel. This pigment change is permanent.
Prostaglandins can also cause periorbital fat atrophy with prolonged use — a subtle hollowing around the eye sometimes called prostaglandin-associated periorbitopathy (PAP). Patients on prostaglandins for many years may notice this. It is reversible on switching to a different drop class.
Systemic side effects are minimal, making prostaglandins safe for patients with heart disease, asthma, or diabetes who cannot tolerate beta blockers.
You can read one of my research papers, indexed on Pubmed, on comparative evaluation of pharmaceutical characteristics of three marketed generic vs branded travoprost formulations , which I co-authored with my colleagues from AIIMS, New Delhi.
You may also want to listen to my talk on holistic approach of glaucoma management at the All India Ophthalmology Conference in 2021.
Beta Blockers — the Most Common Add-On Drop
Beta blockers were the standard first-line treatment for glaucoma before prostaglandins became available. They remain the most widely used add-on drop and are a component of many fixed dose combination formulations.
They work by reducing the production of aqueous humour in the ciliary body, typically lowering IOP by 20 to 25 percent.
Drugs in this class: Timolol (Timoptic, Timoptic XE), Betaxolol (Betoptic S), Carteolol, Levobunolol.
Timolol is non-selective and the most commonly prescribed. Betaxolol is cardioselective (beta-1 selective) and carries a lower risk of respiratory side effects — useful in patients with mild asthma or chronic obstructive pulmonary disease, though still used with caution.
Side effects to know:
Beta blockers are absorbed systemically after instillation. Even a small drop that enters the nasolacrimal duct and reaches the systemic circulation can affect the heart and lungs. Your doctor will ask about asthma, heart block, bradycardia, and severe cardiac failure before prescribing these drops — all are contraindications.
Other systemic effects include fatigue, reduced exercise tolerance, sexual dysfunction, depression, and an effect on blood lipid profiles. Locally, these drops cause reduced tear production — a significant concern for patients who already have dry eye.
Beta blockers lose some of their effectiveness over time in some patients — a phenomenon called long-term drift or escape. If your pressure has crept up on a stable regimen, this is worth discussing.
Alpha-2 Adrenergic Agonists — Dual Mechanism
Alpha agonists lower IOP by both reducing aqueous production and increasing uveoscleral outflow. They are prescribed twice or three times daily and are commonly used as second or third-line add-on therapy. They are also used perioperatively and after laser procedures to blunt IOP spikes.
Drugs in this class: Brimonidine (Alphagan P), Apraclonidine (Iopidine).
Brimonidine is the more commonly used long-term option. Apraclonidine is primarily used short-term around procedures.
Side effects to know:
The most significant local side effect is ocular allergy — a delayed hypersensitivity reaction that develops in a meaningful proportion of patients over time, presenting as redness, itching, and swelling of the lids and conjunctiva. If you develop these symptoms after months on brimonidine, this reaction is the likely cause.
Brimonidine crosses the blood-brain barrier and can cause drowsiness, fatigue, and dry mouth. It must not be used in infants and young children, as it can cause dangerous respiratory depression and apnoea.
Carbonic Anhydrase Inhibitors — Drops and Tablets
Carbonic anhydrase inhibitors (CAIs) reduce aqueous production by blocking the enzyme carbonic anhydrase in the ciliary body. They are available as eye drops (topical CAIs) and as oral tablets.
Topical drugs: Dorzolamide (Trusopt), Brinzolamide (Azopt). Dosed twice or three times daily.
Oral drugs: Acetazolamide (Diamox), Methazolamide. Reserved for short-term use in acute situations — angle closure crises, perioperative pressure control — because systemic side effects limit long-term tolerance.
Side effects to know (topical):
A bitter or metallic taste in the mouth is common and occurs because the drop drains through the nasolacrimal duct and reaches the oropharynx. Punctal occlusion (pressing the inner corner of the eye after instillation) significantly reduces this. Local stinging on instillation and transient blurring are also common.
Topical CAIs should be used with caution in patients with sulphonamide allergy, as cross-reactivity is possible.
Side effects to know (oral):
Acetazolamide causes significant systemic side effects — tingling in the hands and feet, frequent urination, fatigue, loss of appetite, and kidney stones with prolonged use. It depletes potassium and should not be used with certain cardiac medications. It is not a long-term glaucoma solution.
Rho Kinase Inhibitors — the Newest Class
Rho kinase (ROCK) inhibitors are the most recently approved class of glaucoma drops. They lower IOP primarily by relaxing the trabecular meshwork and Schlemm’s canal — improving conventional outflow through the natural drainage pathway that is dysfunctional in most open-angle glaucoma patients. This mechanism is distinct from all other drop classes.
Drug: Netarsudil (Rhopressa), Ripasudil. Available in some markets as a fixed dose combination with latanoprost (Rocklatan).
Side effects to know:
The most striking and common local side effect is conjunctival hyperaemia — pronounced redness of the eye. It affects a significant proportion of users and is the main reason for discontinuation. Corneal verticillata (fine whorl-like deposits on the corneal epithelium) also occur but are reversible on stopping the drug and do not affect vision.
ROCK inhibitors are not yet widely available in India but are an important emerging option, particularly for patients whose pressure is inadequately controlled on existing classes.
Parasympathomimetics (Miotics)
Parasympathomimetics increase aqueous outflow through the trabecular meshwork by contracting the ciliary muscle. They are now rarely used in open-angle glaucoma but remain valuable in angle closure glaucoma — pilocarpine in particular is used to break an acute angle closure attack and to prevent recurrence.
Drugs: Pilocarpine, Carbachol.
Side effects to know:
Pupil constriction is an inevitable effect — it reduces the amount of light entering the eye and significantly impairs night vision. Brow ache and headache are common, particularly early in treatment. The small pupil also reduces visual acuity in patients with central lens opacity (cataract). These effects limit tolerability in younger, working-age patients.
Fixed Dose Combinations — One Bottle, Two Drugs
When a second drop is needed, your doctor will often prescribe a fixed dose combination (FDC) rather than two separate bottles. The advantages are real: fewer drops per day, fewer preservative exposures, lower cost, and better adherence.
Common combinations include prostaglandin plus beta blocker (the most widely prescribed), beta blocker plus carbonic anhydrase inhibitor, beta blocker plus alpha agonist, and prostaglandin plus beta blocker plus carbonic anhydrase inhibitor (triple combinations).
Your doctor will always choose drugs with different mechanisms of action for a combination — there is no benefit in combining two drugs that work the same way.
Preservatives in Glaucoma Drops — Why They Matter
Most multi-dose glaucoma eye drop bottles contain a preservative, most commonly benzalkonium chloride (BAK). Preservatives prevent microbial contamination and extend shelf life. They also damage the ocular surface with repeated exposure.
BAK disrupts the tear film, damages corneal and conjunctival epithelial cells, and causes or worsens dry eye syndrome. Patients on two or three preserved drops multiple times daily accumulate a significant daily preservative burden. Over years, this can cause chronic ocular surface disease that complicates both drop tolerance and future surgical outcomes.
Preservative-free formulations of most major glaucoma drops are available — in unit-dose vials. They cost more but are strongly preferable for patients with existing dry eye, those on multiple drops, and those who have been on drops for many years. If your eyes are chronically red, uncomfortable, or sensitive on your current drops, ask your doctor specifically about switching to preservative-free versions.
How to Use Glaucoma Eye Drops Correctly
Correct technique matters. A drop that misses the eye, runs down the cheek, or is immediately blinked away delivers no pressure-lowering benefit.
Wash your hands before instilling drops. Tilt your head back or lie down. Pull the lower lid gently downward to create a small pocket. Hold the bottle above the eye without touching the tip to any surface. Squeeze one drop into the pocket. Close your eye gently — do not blink hard. Press the inner corner of the eye (the punctum) with one finger for one to two minutes. This is punctal occlusion. It reduces systemic absorption by blocking drainage through the tear duct into the bloodstream.
If you use more than one drop, wait at least five minutes between them. The first drop is partly washed out by the second if they are instilled too close together.
If a drop misses the eye entirely, you may instil one more. If you are not sure whether it landed, do not add a second — excess drop does not improve efficacy and increases systemic exposure.
You may want to see a video explaining the technique.
What Happens If You Miss a Dose
Missing one dose occasionally is unlikely to cause permanent harm. If you miss a dose, instil the drop as soon as you remember — unless it is almost time for the next dose, in which case skip the missed one. Never double up.
Missing doses repeatedly is a serious problem. Glaucoma is a disease of cumulative damage. Pressure that rises each time you skip a drop — even temporarily — contributes to optic nerve loss. This is one reason some patients progress despite being on treatment. Honest discussion with your doctor about adherence difficulties matters more than suffering in silence.
Side Effects: When to Call Your Doctor
Most side effects from glaucoma drops are local and manageable. Some require prompt attention.
Call your doctor if you develop sudden severe eye redness with pain or blurred vision — this may indicate an acute pressure spike or anterior uveitis. Contact your doctor if you develop significant lid swelling, discharge, or intense itching — this may be a drug allergy. Inform your doctor if you notice palpitations, worsening breathlessness, or unusual fatigue on beta blocker drops — systemic absorption can be clinically significant. And tell your doctor if your drops sting so severely that you are not using them consistently — there are alternatives.
When Eye Drops Are Not Enough
Here is what you need to understand about glaucoma treatment. Drops control glaucoma in most patients. In some, they do not achieve the target IOP despite two or three medications. In others, drop tolerance is poor, adherence is impossible, or the disease is too advanced to rely on drops alone. In these situations, laser treatment or glaucoma surgery becomes necessary.
Selective laser trabeculoplasty (SLT) is a safe, well-tolerated office procedure that improves aqueous drainage and can replace or reduce the need for drops in suitable patients. It is increasingly used earlier in the treatment pathway.
Surgery — trabeculectomy, glaucoma drainage devices, or minimally invasive glaucoma surgery (MIGS) — offers more durable IOP control but carries procedural risk. The decision to operate is made carefully, after weighing how much pressure reduction is needed, how much nerve damage already exists, and the patient’s overall health and preferences.
If you have been on maximum medical therapy and your glaucoma is still progressing, a specialist opinion on surgical options is appropriate. You can request a second opinion here.
[H2] Frequently Asked Questions About Glaucoma Eye Drops
Can I stop my glaucoma drops if my pressure is normal?
No. Your pressure is normal because of the drops. Stopping them will cause pressure to rise again. Glaucoma drops are a lifelong commitment unless your doctor specifically advises otherwise after surgery or laser.
My drops are making my eyes very red. Should I stop them?
Do not stop without speaking to your doctor first. Redness can be a preservative reaction, a drug allergy, or a class effect (prostaglandins commonly cause mild redness). There are almost always alternatives. Stopping drops abruptly without a plan risks a pressure spike.
Do glaucoma drops affect the rest of my body?
Beta blockers in particular are absorbed systemically and can affect heart rate, blood pressure, breathing, and mood. Alpha agonists can cause drowsiness. Carbonic anhydrase inhibitor tablets cause significant systemic effects; the eye drops far less so. Always tell every doctor — cardiologist, physician, anaesthetist — that you are on glaucoma drops.
I have dry eyes and my doctor wants to start glaucoma drops. Is this a problem?
Yes, and it deserves a frank conversation. Most preserved glaucoma drops worsen dry eye over time. Ask your doctor about preservative-free formulations from the outset. If you are already on dry eye treatment, your medication regimen will need to be coordinated carefully.
Can I use my glaucoma drops with contact lenses?
Most preserved drops should not be instilled while wearing soft contact lenses — the preservative absorbs into the lens. Remove lenses before instilling drops and wait at least 15 minutes before reinserting them. Preservative-free unit-dose drops do not carry this restriction.
I keep forgetting my evening drop. What can I do?
Link the drop to an existing evening habit — brushing teeth, switching off the television. Set a phone alarm. Keep the bottle visible where you will see it at the right time. If you are on a twice-daily drop, ask your doctor whether a once-daily prostaglandin might be a better fit for your routine.
My drops are very expensive. Is the generic version equally effective?
Generic glaucoma drops contain the same active ingredient at the same concentration. For most patients, the generic performs identically. Where there may be minor differences is in the vehicle formulation and preservative, which can affect tolerability. If you switch to a generic and notice increased irritation or reduced efficacy, tell your doctor.
You can read one of my research papers, indexed on Pubmed, on comparative evaluation of pharmaceutical characteristics of three marketed generic vs branded travoprost formulations , which I co-authored with my colleagues from AIIMS, New Delhi which discusses this topic.
I was diagnosed elsewhere and am not sure if my current drops are right for me. What should I do?
Bring your bottles, your previous reports, and your visual field and OCT results to your next consultation. A second opinion specifically to review whether your current regimen is achieving adequate pressure control — and whether your optic nerve is stable — is entirely appropriate. Request one here.
You can read one of my research papers, indexed on Pubmed, on Glaucoma Drug Prescription Pattern in North India: Public vs Private Sector Hospitals , which I co-authored with my colleagues from PGIMER, Chandigarh which discusses this topic.
Read the research articles
This article was written by Dr Shibal Bhartiya, fellowship-trained glaucoma specialist and Mayo Clinic Research Collaborator, Clinical Director at Marengo Asia Hospitals, Gurugram, known for ethical, patient-centred glaucoma care and independent glaucoma second opinions. This article was edited in April 2026.
She has published peer-reviewed research on glaucoma management, examining how treatment decisions should balance medical evidence, patient preferences, and long-term vision outcomes.
As Editor-in-Chief of Clinical and Experimental Vision and Eye Research and Executive Editor of the Journal of Current Glaucoma Practice (Pubmed Indexed, official journal of the International Society of Glaucoma Surgery), Dr Shibal Bhartiya brings editorial and research depth to every clinical decision. Her 200+ publications, including 90+ PubMed-indexed publications and 28 edited textbooks span glaucoma biology, surgical outcomes, health equity, and emerging diagnostics.
Her work can be accessed on Pubmed, Google Scholar, ResearchGate and ORCID.
Dr Shibal Bhartiya
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