Glaucoma Basics: Symptoms, Diagnosis, Treatment & Prevention

Sep, 1 2025

Half of the people who have glaucoma don’t know it yet. That’s the trap: you feel fine while the optic nerve is quietly getting squeezed and starved. If you want the basics without medical-school jargon, here’s the plain-English guide: what it is, who’s most at risk, how doctors find it, what treatment looks like in 2025, and small daily habits that actually protect your sight. This won’t replace a real exam, but it will help you walk in prepared and walk out confident.

• TL;DR: Glaucoma is optic nerve damage (often from high eye pressure) that can lead to permanent, silent vision loss-early detection matters.
• Most common type has no symptoms until late. Sudden eye pain with halos and nausea is an emergency.
• Diagnosis uses pressure checks, angle exam, optic nerve imaging, and visual field testing.
• First-line treatment is pressure lowering: drops, laser (often SLT), or surgery. Target is usually 20-30% pressure reduction from your baseline.
• Don’t wait for blurry vision. If you’re over 60, have a family history, are of African, Hispanic/Latino, or Asian ancestry, or use steroids often, book a comprehensive eye exam.

What It Is, Who’s at Risk, and Signs You Shouldn’t Ignore

Glaucoma isn’t one disease. It’s a group of conditions where the optic nerve-the cable that carries images to your brain-gets damaged. The biggest driver is intraocular pressure (IOP) that’s too high for your nerve to tolerate. Some people have “normal” pressure but still get damage because their nerve is vulnerable. Vision loss from glaucoma is permanent, so the win is catching it before you notice anything.

The two big buckets:

• Primary open-angle glaucoma (POAG): The most common. The drain inside the eye clogs slowly. No pain. No redness. No dramatic symptoms until you’ve already lost part of your side vision.
• Angle-closure glaucoma: The eye’s drainage angle gets blocked. This can build pressure fast and hard. It may come on gradually in some people, but when it’s acute, it’s an emergency.

Other types you might hear about:

• Normal-tension glaucoma: Damage happens even with pressure in the “normal” range. Blood flow and optic nerve resilience play a bigger role here.
• Secondary glaucoma: From another problem-long-term steroid use, eye injury, inflammation, neovascularization (often linked to diabetes), or advanced cataracts.

Who’s at higher risk? A quick rule of thumb: add points for each box you tick. More points, more reason to get checked sooner.

• Age: 0 points under 40; 1 point ages 40-59; 2 points ages 60+
• Family history (parent or sibling): 2 points
• Ancestry: African or Afro-Caribbean (2 points), Hispanic/Latino (1 point), East/Southeast Asian (1-2 points for angle-closure risk)
• High eye pressure in the past: 2 points
• Thin corneas (pachymetry): 1 point
• Steroid use (pills, inhalers, skin creams near eyes): 1 point
• Severe nearsightedness or farsightedness: 1 point
• Diabetes, sleep apnea, migraines or Raynaud’s (normal-tension risk): 1 point

0-1 points: routine eye exams per age. 2-3 points: book a comprehensive exam this year. 4+ points: prioritize within the next 1-3 months. If you’ve ever been told you have “narrow angles,” do it sooner.

Symptoms-what’s real vs myth:

• Open-angle glaucoma: Typically no symptoms until late. Don’t wait for blurry vision-by then, damage is already done.
• Angle-closure attack (emergency): Severe eye pain or headache, halos around lights, sudden blurry vision, nausea/vomiting, a red, hard eye. Call emergency care immediately. Delays can cost vision.
• Children: Congenital glaucoma is rare but serious-tearing, light sensitivity, large-looking corneas. Needs urgent pediatric eye care.

Why early matters: The optic nerve doesn’t regenerate. Once fibers are gone, they’re gone. The good news? If you lower pressure early enough, you can preserve the vision you have and slow or stop progression.

One common pitfall: blaming “tired eyes” or “bad lighting” for missing side vision. If driving feels different-more close calls at intersections, trouble noticing pedestrians on the edges-get checked.

How Doctors Diagnose and Treat It (What to Expect, Step-by-Step)

Your first comprehensive evaluation maps both your pressure and your optic nerve. Expect this sequence:

1. History and risk review: Age, family history, steroid use, past eye injuries, migraines, sleep apnea.
2. Pressure check (tonometry): The blue-light device or the air puff. The blue-light method is usually more precise. Your pressure changes throughout the day; one number isn’t the whole story.
3. Angle exam (gonioscopy): A small contact lens shows whether your drainage angle is open or narrow. This decides if we’re talking open-angle or angle-closure risk.
4. Optic nerve evaluation: Slit-lamp exam plus photos or OCT (optical coherence tomography) to measure nerve fiber thickness.
5. Visual field test: You press a button for dim dots of light. It maps blind spots. It’s a little awkward the first time; most people get better by the second test.
6. Corneal thickness (pachymetry): Thin corneas can make pressure readings look lower than “true,” and they raise risk.

Tip: Bring your glasses, current drops, and a list of meds (including inhalers and skin creams). Ask for your baseline numbers: IOP, corneal thickness, OCT summary, and first visual field printout. Keep them-future you will thank you.

What “good care” aims for: Lowering eye pressure to a level your nerve can live with. For many people, that means 20-30% lower than the starting pressure. Doctors adjust the target if your nerve looks fragile, if you have normal-tension glaucoma, or if progression shows up on repeat tests.

Treatment menu in 2025:

• Prescription eye drops (first-line for many):
  • Prostaglandin analogs (latanoprost, bimatoprost, travoprost): Often once nightly. Can darken eyelids/iris, grow lashes, and cause redness.
  • Beta-blockers (timolol): Usually morning. Can slow heart rate or worsen asthma-tell your doctor about breathing or heart issues.
  • Alpha agonists (brimonidine): Twice or three times daily. Possible fatigue or dry mouth.
  • Carbonic anhydrase inhibitors (dorzolamide, brinzolamide; oral acetazolamide short-term): Can sting; oral versions can tingle fingers/toes and upset the stomach.
  • Combo drops: Two meds in one bottle to simplify life.
• Laser therapy:
  • Selective Laser Trabeculoplasty (SLT): Treats the drain to improve outflow. Takes minutes, minimal downtime. Evidence supports SLT as a first-line option for many with open-angle glaucoma or ocular hypertension. It can be repeated.
  • Laser peripheral iridotomy (LPI): A tiny opening in the iris to prevent or treat angle-closure. Often recommended if you have narrow angles.
• Surgery:
  • MIGS (minimally invasive glaucoma surgery): Devices like iStent or Hydrus placed during cataract surgery in mild-to-moderate disease to lower pressure and cut drop burden.
  • Trabeculectomy or tube shunt: For moderate to advanced disease or when drops/laser aren’t enough. Stronger pressure lowering, higher risk and more follow-up.
  • Cyclophotocoagulation: Lowers fluid production by treating the ciliary body. Various techniques exist; used when other options fall short or in specific scenarios.

Side-effect savvy and adherence tips:

• Perfect your drop technique. Steps below. Two big wins: don’t touch the bottle to your eye, and press the inner corner of your eyelid gently for 1-2 minutes to keep the medication in the eye and out of your bloodstream.
• Space multiple drops at least 5 minutes apart so the first one isn’t washed out.
• If redness or stinging lasts more than two weeks, tell your doctor. A simple switch (to preservative-free or a different class) can fix it.
• Set a phone reminder. Pair the drop with a daily habit (toothbrushing). Track doses during travel.
• If you can’t keep up with drops or they don’t hit target pressure, SLT is a strong option to consider.

How to choose among drops, laser, and surgery? Think about your starting pressure, nerve status, lifestyle, and your ability to keep up with drops.

• If you’re newly diagnosed with open-angle glaucoma or ocular hypertension and hate the idea of daily drops: Ask about SLT as a first step.
• If you already need cataract surgery and you’re on 1-2 drops: Ask whether adding a MIGS device during the same surgery makes sense.
• If your fields or OCT are worsening despite maxed-out drops and prior laser: It’s time to discuss trabeculectomy or a tube shunt.
• If you have narrow angles: LPI is often recommended to prevent angle-closure. Your doctor may still use other treatments if pressure or nerve findings need it.

What the evidence says in plain terms: Big studies have shown that lowering pressure slows vision loss, whether your baseline pressure is high or normal. The LiGHT trial found SLT can control pressure as well as drops for many people and reduce the number of meds needed over years. The American Academy of Ophthalmology’s guidance targets meaningful pressure reduction early, then watches nerve structure (OCT) and function (fields) to refine the plan.

Drop technique (quick, zero-drama):

1. Wash hands. Shake bottle if the label says so.
2. Tilt head back or lie down. With a clean finger, gently pull the lower lid down to form a small pocket.
3. Look up and squeeze out one drop into the pocket. One drop is enough; a second usually spills out.
4. Close your eye. Press the inner corner (near the nose) gently for 1-2 minutes.
5. Blot excess. Wait 5 minutes before another drop or different bottle.

Common myths to ditch:

• “I’ll feel it when it starts.” Not for open-angle glaucoma.
• “If my pressure is normal, I can’t have glaucoma.” Normal-tension glaucoma exists.
• “Marijuana treats glaucoma.” It lowers pressure briefly (hours), not safely or consistently enough for real care.

Living With Glaucoma: Daily Habits, Checklists, FAQs, Next Steps

You don’t need a new personality to protect your vision-just a few smart habits and a plan. Small changes chip away at pressure and protect nerve health.

Daily habits that help (and a few to avoid):

• Move your body: Regular moderate aerobic exercise (brisk walking, cycling) can nudge eye pressure down. If you have advanced disease, ask your doctor about safe targets.
• Skip head-down poses: Prolonged headstands or deep inversion yoga can spike eye pressure. Child’s pose is fine; handstands are not your friend.
• Watch caffeine surges: A big shot of espresso can bump pressure slightly for a short time. Steady intake is better than spikes.
• Hydrate smart: Avoid chugging a liter of water in one go. Sip steadily over time.
• Sleep setup: Slightly elevated head-of-bed may help. If you have sleep apnea, use your therapy and tell your eye doctor.
• Medication check: Some cold/antihistamine meds with anticholinergic effects can provoke angle-closure in people with narrow angles. If you’ve been told your angles are narrow, ask before taking new meds.
• Eye-friendly environment: Use brighter, even lighting. Increase font sizes and contrast on screens. Polarized sunglasses cut glare outdoors.

Driving and safety:

• Ask for a visual field printout and discuss whether it meets your local driving standards.
• At night, reduce glare: keep the windshield clean inside and out, use anti-reflective lenses.
• At home, add night lights in halls and bathrooms to reduce fall risk.

Pre-visit checklist (bring this on your phone):

• List of all meds and supplements, including inhalers and steroid creams.
• Your glasses or contact lens prescription and the actual glasses.
• Any past eye records: pressure readings, OCTs, visual fields.
• Insurance info, pharmacy info, allergies list.
• Three questions you want answered. Example: What’s my target pressure? How will we know if I’m stable? What’s Plan B if this doesn’t work?

Red flags-don’t wait:

• Sudden severe eye pain, headache, halos around lights, nausea, and a red eye.
• Sudden vision loss or a dark curtain in your vision.
• Eye trauma with vision changes.

Questions to ask your eye doctor:

• What type of glaucoma do I have? Open-angle, narrow-angle, normal-tension, or secondary?
• What’s my baseline pressure and target pressure?
• What does my OCT show-any thinning yet?
• How reliable was my visual field test? Do we need to repeat it?
• Would SLT be a good first-line or second-line option for me?
• If I’m having cataract surgery, should we add a MIGS device?
• How often should I return for pressure checks and imaging?

Mini-FAQ:

• Is glaucoma curable? No. It’s controllable. The goal is to preserve the vision you have.
• Can I prevent it? You can’t change your genes or age, but you can catch it early. Regular comprehensive eye exams are the most powerful prevention of vision loss.
• Do I need screening if I have no symptoms? The U.S. Preventive Services Task Force says evidence is insufficient to recommend population screening in primary care, but the AAO recommends comprehensive eye exams at regular intervals, especially if you have risk factors.
• What’s the difference between open-angle and angle-closure? Open-angle means the drain is open but not working well-slow, silent damage. Angle-closure means the drain is physically blocked-can be sudden and painful.
• Can cataract surgery help glaucoma? Removing the lens can deepen the angle and lower pressure a bit, especially in angle-closure. Adding a MIGS device during cataract surgery can provide extra lowering in mild to moderate open-angle glaucoma.
• Is LASIK okay? If you already have glaucoma, talk to your surgeon. Lasik changes corneal thickness, which can affect pressure readings. PRK is sometimes preferred in select cases.
• Are vitamins useful? No supplement has proven to prevent or treat glaucoma. Eat for heart health-your optic nerve likes good blood flow.
• Does staring at a screen cause glaucoma? No. Screen time doesn’t cause it, but dry eye and eye strain can make you feel worse. Use 20-20-20 breaks.
• Can I use marijuana for glaucoma? It can lower pressure briefly, but not in a reliable, round-the-clock way. It’s not a substitute for drops, laser, or surgery.
• Pregnancy and drops? Some drops aren’t ideal in pregnancy or breastfeeding. If you’re planning or pregnant, tell your doctor-your plan may change.
• Are air-puff readings accurate? They’re a screening tool. Goldmann applanation is the gold standard. Your doctor will interpret readings with corneal thickness in mind.

Simple decision guide for your next step:

• If you’re under 40 with no risk factors and no symptoms: Book a routine comprehensive eye exam every 2-4 years, sooner if your family history changes.
• If you’re 40-59 or have one risk factor: Every 1-2 years.
• If you’re 60+ or have multiple risk factors: Every 6-12 months, or as your doctor advises.
• If you’ve been told you have ocular hypertension (high pressure, no damage): Ask about your 5-year risk and whether drops or SLT would lower it.
• If you’ve been diagnosed with glaucoma: Stick to your follow-up schedule (often every 3-6 months), take meds as directed, and ask about SLT if drops are tough to manage.
• If you’ve ever had severe eye pain with halos and nausea: That’s an emergency pattern-seek immediate care if it happens again, and ask about narrow angles and LPI.

What to do while you wait for your appointment:

• Gather past eye records if you have them. It helps your doctor see progression vs noise.
• Make a meds list and note any steroid use.
• Start gentle, regular exercise if your doctor has cleared you for it.
• Cut back on late-night head-down screen use; stack pillows and keep your head slightly elevated in bed.

Credible places your eye doctor draws guidance from: American Academy of Ophthalmology Preferred Practice Pattern (updated 2023), National Eye Institute epidemiology, and trials like OHTS (ocular hypertension), LiGHT (laser first-line), and CNTGS (normal-tension glaucoma). If your plan lines up with these, you’re on solid ground.

Final thought: you don’t need to become an expert-you just need to recognize the silent nature of glaucoma, show up for exams, and pick a treatment plan you can actually stick with. That’s how people keep their driver’s license, their hobbies, and their independence.