Cataracts and Eye Pressure: What the Connection Is
Cataracts themselves do not directly raise the pressure inside your eye. A cataract is a clouding of the lens — it blocks light but does not change the fluid dynamics that control eye pressure. However, certain types of cataracts and the way they develop can create conditions that do raise pressure, and this matters because high eye pressure can damage the optic nerve and lead to glaucoma.
The most common scenario is a mature or advanced cataract. As the cataract becomes denser and larger, the lens can swell. If it swells enough, it can physically push against the iris (the colored part of your eye) and block the drainage channels where fluid normally leaves the eye. When fluid cannot drain, pressure builds. This is called phacomorphic glaucoma, and it can happen suddenly.
A second, less common path is phacoanaphylactic glaucoma, which occurs after cataract surgery if lens material leaks into the eye and triggers inflammation. The inflammation blocks drainage and raises pressure. This is rare with modern surgical techniques but remains a known risk.
Key Takeaways
- A cataract itself does not raise eye pressure, but a dense, mature cataract can swell and physically block the eye's drainage channels, causing pressure to spike.
- Phacomorphic glaucoma — pressure caused by a swollen cataract — can develop suddenly and requires urgent treatment to prevent permanent vision loss.
- If you have both cataracts and a history of glaucoma or high eye pressure, your eye doctor should monitor you more closely and may recommend earlier cataract surgery.
- After cataract surgery, inflammation can occasionally block drainage and raise pressure, though this is uncommon with current surgical methods.
- Regular eye pressure checks are the only way to know if your cataract is affecting drainage — you cannot feel high eye pressure yourself.
How a Swollen Cataract Blocks Fluid Drainage
Inside your eye, a clear fluid called aqueous humor is constantly produced and drained. The drainage happens through tiny channels near the iris, in an area called the angle. As long as fluid flows in and out at the same rate, pressure stays normal.
When a cataract becomes mature — usually after years of gradual clouding — the lens proteins absorb water and the lens swells. If the lens is large enough, it can push the iris forward and physically narrow or block the angle where fluid drains. The fluid backs up, and pressure rises. This can happen over days or weeks, or sometimes more suddenly.
The risk is highest if you have a very dense cataract in one eye and have not had surgery yet. Your eye doctor can see during an exam whether your angle is narrow and whether your lens is large enough to pose a risk. If both are true, they may recommend surgery sooner rather than waiting.
Signs That a Cataract May Be Raising Your Eye Pressure
High eye pressure itself has no symptoms — many people with glaucoma do not know they have it until vision loss occurs. However, if a cataract causes a sudden, significant pressure spike, you may notice symptoms of acute angle-closure glaucoma: severe eye pain, blurred or hazy vision, halos around lights, redness, and sometimes nausea or vomiting.
These symptoms are a medical emergency. If you experience them, go to an emergency room or urgent eye care clinic the same day. Acute pressure spikes can damage the optic nerve within hours.
More often, pressure rises gradually and silently. This is why regular eye pressure checks matter, especially if you have cataracts, a family history of glaucoma, or are over 60. Your eye doctor will measure your pressure at routine visits and can spot a rise before it causes harm.
Who Is at Higher Risk
You face a higher risk of cataract-related pressure problems if you have a combination of factors. People with narrow angles — a structural feature your eye doctor can measure — are at greater risk because their drainage channels are already tight, and a swollen lens can block them more easily. People of Asian or Inuit descent have narrower angles on average.
If you already have glaucoma or a history of high eye pressure, a developing cataract needs closer watching. Your eye doctor may recommend surgery at an earlier stage of cataract development than they would for someone without glaucoma, because the risk of pressure complications is higher.
Age also matters. Cataracts develop slowly over decades, so they are most common in people over 60. By that age, the eye's drainage system may already be less efficient, making pressure problems more likely if a cataract swells.
What Happens During an Eye Pressure Check
Your eye doctor measures pressure using a device called a tonometer. The most common method is applanation tonometry, in which a small probe gently flattens a tiny area of your cornea (the clear front of your eye) after numbing drops are applied. You feel pressure but not pain. The measurement takes seconds.
Normal eye pressure ranges from about 10 to 21 millimeters of mercury (mmHg), though this varies slightly between people and even between the two eyes. A single high reading does not always mean you have a problem — pressure fluctuates throughout the day — but a pattern of high readings or a sudden jump is a signal to watch closely.
If your pressure is high or rising, your eye doctor may recommend more frequent checks, imaging of your optic nerve, or visual field testing to see whether pressure has already caused damage. If you have a cataract and your pressure is climbing, surgery to remove the cataract may be recommended to restore normal drainage.
Cataract Surgery and Eye Pressure
Removing the cataract usually solves the pressure problem if the cataract was the cause. Once the swollen lens is gone, the iris moves back to its normal position, the drainage angle opens, and fluid can flow freely again. Pressure typically returns to normal within days or weeks after surgery.
In rare cases, inflammation after surgery can temporarily raise pressure. Your eye doctor will prescribe anti-inflammatory drops and may add pressure-lowering drops if needed. This usually resolves within a few weeks as the eye heals.
If you have both a cataract and glaucoma, surgery removes the cataract but does not cure the glaucoma. You will still need glaucoma treatment — usually eye drops — to keep pressure controlled long-term. However, removing the cataract may reduce the pressure load and make glaucoma easier to manage.
Monitoring Your Eyes Between Doctor Visits
You cannot measure your own eye pressure at home, and you cannot feel it rising. However, you can watch for warning signs. If you notice a gradual increase in blurriness beyond what your cataract alone would cause, halos around lights, or eye discomfort, contact your eye doctor. These can signal a pressure problem.
Keep a regular schedule of eye exams — at least every one to two years if you have cataracts, and more often if you have glaucoma or a family history of it. Your eye doctor will track your pressure over time and spot trends that matter.
If you have been told you have narrow angles or are at risk for angle-closure glaucoma, avoid dilating eye drops (used in some exams) without your doctor's knowledge, and be cautious with certain medications like antihistamines and decongestants, which can trigger angle closure in susceptible people. Always tell your eye doctor about all medications you take.
Frequently Asked Questions
Can I have a cataract and high eye pressure without knowing it?
Yes. Neither cataracts nor high eye pressure cause symptoms until they are advanced. A cataract causes gradual blurring; high pressure causes no symptoms at all until vision loss occurs. This is why regular eye exams are essential, especially after age 60.
If my cataract is small, do I need to worry about eye pressure?
Small cataracts rarely raise eye pressure because they do not swell enough to block drainage. However, if you have narrow angles or glaucoma, your eye doctor should monitor you. As the cataract grows over years, the risk increases.
What is the difference between phacomorphic and phacoanaphylactic glaucoma?
Phacomorphic glaucoma is caused by a swollen cataract blocking drainage before surgery. Phacoanaphylactic glaucoma is caused by inflammation and lens material leaking into the eye after surgery. Both raise pressure, but they happen at different times and are treated differently.
Will cataract surgery lower my eye pressure if I have glaucoma?
Surgery will remove the pressure caused by the cataract itself, but it does not cure glaucoma. If you have glaucoma, you will still need drops or other treatment to control pressure long-term. However, removing the cataract may make pressure easier to manage.
How often should I have my eye pressure checked if I have a cataract?
At minimum, every one to two years during routine exams. If your eye doctor sees signs of narrow angles, a dense cataract, or rising pressure, they will recommend more frequent checks — sometimes every few months. Ask your doctor what schedule is right for you.