Glaucoma is a condition where the optic nerve, which connects the eye to the brain, becomes damaged. This damage is often caused by abnormally high pressure in the eye. The increased eye pressure is usually caused by inadequate drainage of the aqueous humor, the fluid inside the front part of the eye.
Can you physically feel the increased eye pressure of glaucoma?
In most cases, no, increased eye pressure from glaucoma cannot be physically felt. The intraocular pressure (IOP) increase is gradual, so the eyes do not noticeably feel different. Glaucoma is nicknamed the “silent thief of sight” because vision loss occurs without symptoms until the late stages.
However, some people with acute angle-closure glaucoma, a sudden form of glaucoma, may experience eye pain, blurred vision, headaches, rainbow-colored halos around lights, nausea or vomiting. This occurs when the drainage angle in the eye becomes completely blocked, leading to a sudden and more extreme IOP increase.
Why don’t you typically feel glaucoma pressure?
There are a few key reasons why the eye pressure increase of glaucoma goes unnoticed:
- The optic nerve lacks pain receptors – While other parts of the eye contain pain receptors, the optic nerve itself does not. Therefore, even as glaucoma damages the optic nerve, it does not cause pain or obvious symptoms.
- IOP rises slowly over time – In chronic glaucoma cases, IOP increases slowly over many months or years. The eyes adjust to the gradual IOP rise, so it goes undetected.
- No reference for “normal” eye pressure – People have no innate sense of what their normal IOP should feel like. Without a reference point, it’s impossible to self-diagnose elevated IOP.
- Vision loss is peripheral – Glaucoma usually affects peripheral vision first. Central vision used for reading, driving, etc. remains unaffected until late stages. People often don’t notice peripheral vision changes.
For these reasons, glaucoma patients are usually unaware of the increased eye pressure and progressive damage to their optic nerves until they experience vision loss. Regular eye exams are essential to detect glaucoma early before noticeable vision loss occurs.
Are there any symptoms that may indicate glaucoma?
Although the increased eye pressure of glaucoma isn’t felt, some people do experience early symptoms including:
- Gradual vision loss – Glaucoma initially causes peripheral vision loss. This can go unnoticed until advanced stages when central vision becomes affected.
- Blind spots – Scattered blind spots may occur in the field of vision. The blind spots are usually not noticeable at first.
- Halos around lights – Some people see rainbow-colored rings or halos around bright lights as a very early symptom.
However, many glaucoma patients don’t notice any symptoms until substantial irreversible vision loss has occurred. That’s why regular comprehensive eye exams are essential to evaluate the optic nerve and check eye pressure.
Who is at risk of glaucoma?
Here are the main risk factors for developing glaucoma:
| Risk Factor | Description |
|---|---|
| Age over 60 | The risk of glaucoma increases significantly after age 60. People over 80 have a 10% chance of developing glaucoma. |
| Family history | Having a close relative with glaucoma increases your risk up to 4 times. |
| High eye pressure | IOPs above 21 mmHg increase glaucoma risk. However, some people get glaucoma with normal IOPs. |
| Farsightedness | People who are very farsighted are at greater risk. |
| Thin cornea | A unusually thin cornea leads to higher IOP readings. |
| Race | Glaucoma is 6-8 times more common in African Americans. |
| Eye injuries | Past eye injuries or eye surgery can increase risk. |
| Steroid medications | Prolonged steroid treatment, including eyedrops, can trigger glaucoma. |
How is glaucoma detected?
Glaucoma can’t be self-diagnosed, since the elevated eye pressure isn’t felt. A comprehensive eye exam is required to check for glaucoma by evaluating:
- Eye pressure – Tonometry measures IOP. Readings above 21 mmHg are suspicious for glaucoma.
- Optic nerve exam – Ophthalmoscopy looks for optic nerve damage.
- Visual field test – Perimetry maps peripheral vision looking for blind spots.
- Corneal thickness – Thin corneas may give falsely high pressure readings.
These tests allow the eye doctor to detect increased IOP, optic nerve damage, and vision changes even before symptoms appear. Some people have normal eye pressures but still develop optic nerve damage needing glaucoma treatment.
Are eye pressure readings always accurate?
Tonometry eye pressure readings may sometimes be inaccurate. Thicker corneas can yield falsely high readings, while thin corneas produce low readings. Tonometry may need calibration with a corneal pachymetry test. The most accurate IOP measurements are obtained by averaging results from different tonometry methods.
What are the different types of glaucoma?
There are two main categories of glaucoma:
Open-angle glaucoma
This is the most common glaucoma type in the United States. Open-angle means the drainage angle where the iris meets the cornea is open and appears normal. However, aqueous fluid still doesn’t drain properly, causing slow IOP buildup with no symptoms until later vision loss.
Angle-closure glaucoma
This occurs when the drainage angle is physically blocked, preventing aqueous humor drainage and causing a quick pressure spike. Subtypes include:
- Acute angle-closure – Sudden, extremely high IOP causes an attack of eye pain, blurred vision, headaches, halos around lights, nausea.
- Chronic angle-closure – The drainage angle is partially closed, leading to gradually increasing IOP which typically goes unnoticed until later vision problems.
Who should be tested for glaucoma?
The American Academy of Ophthalmology recommends regular glaucoma testing for:
- African Americans over age 40
- Everyone over age 60, especially Mexican Americans
- People with family history of glaucoma
- People with high eye pressure or thin corneas
- Diabetics
- Those with past eye injuries
Early screening allows glaucoma to be detected and treated at initial stages before extensive vision damage occurs. Most doctors recommend comprehensive eye exams every 1-2 years for at-risk individuals and those over age 65.
What happens if glaucoma is left untreated?
Untreated glaucoma causes progressive damage to the optic nerve fibers and visual field loss:
- Blind spots enlarge and merge together
- Peripheral vision narrows further
- Central vision becomes affected
- Blindness results after extensive optic nerve damage
Glaucoma is the leading cause of irreversible blindness worldwide. Significant vision disability or complete blindness can result in just a few years if high eye pressure damages the optic nerve without treatment. That’s why early detection and glaucoma therapy is critical to preserve sight.
Can glaucoma vision loss be reversed?
Unfortunately, glaucoma damage to the optic nerve fibers and vision loss cannot be reversed. However, further vision loss can usually be prevented with treatment. That’s why glaucoma therapy focuses on lowering IOP to a safe level and preventing additional vision deterioration.
What are the glaucoma treatment options?
Glaucoma cannot be cured, but treatment aims to lower eye pressure and slow disease progression. Treatment options include:
Medicated eye drops
Glaucoma eye drops, used daily, decrease fluid production or improve fluid drainage from the eye. Multiple types of drops with different active ingredients are available. Eye drops alone sufficiently control glaucoma for most patients. Some common glaucoma drops include:
- Prostaglandins – Most commonly used first-line glaucoma eye drops like Lumigan or Xalatan.
- Beta blockers – Reduce aqueous humor production, with brands such as Timoptic.
- Alpha agonists – Also reduce fluid production, such as Alphagan or Iopidine.
- Carbonic anhydrase inhibitors – Improve fluid drainage from the eye.
Laser therapy
Laser trabeculoplasty procedures help aqueous humor drain better from the eye using laser burns. Selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT) are two types. Laser therapy reduces IOP by about 20-30% with minimal side effects.
Surgery
Glaucoma surgery creates an alternate drainage pathway when drops and laser treatments aren’t sufficiently effective. Common surgeries include:
- Trabeculectomy – Creates drainage opening in the trabecular meshwork.
- Glaucoma drainage implant – Shunts fluid from the eye into a plate implant.
- Laser cyclophotocoagulation – Decreases fluid production by coagulating the ciliary processes.
Surgery is often the last resort after drops and laser procedures fail, due to its risks and complications.
What is the prognosis for glaucoma patients?
With early diagnosis and timely treatment, most glaucoma patients retain functional vision for life and blindness can be prevented. However:
- Adherence to medication is crucial – Daily eye drop use is needed.
- IOP and optic nerve damage need monitoring – Lifelong eye exams are required.
- Progression can’t always be halted – 10-15% still experience vision loss.
Of treated patients, most maintain lifelong visual acuity of 20/40 or better. However, regular ophthalmologist visits are imperative because glaucoma can progress despite lowered IOPs. Early intervention provides the best prognosis before extensive optic nerve damage occurs.
How does glaucoma ultimately cause blindness?
Glaucoma blindness occurs by the following sequence of events:
- Inadequate drainage of aqueous humor and gradual IOP increase in the anterior chamber.
- Raised IOP compresses and damages the optic nerve where it exits the eye.
- Progressive loss and death of retinal ganglion cells that form the optic nerve.
- Thinning of the nerve fiber layer of the retina as optic nerve fibers die off.
- Irreversible blindness as extensive optic nerve damage accumulates.
Although not immediately life-threatening, advanced glaucoma causing total vision loss can severely reduce patients’ quality of life. However, blindness is preventable with early diagnosis and optic nerve protection using IOP-lowering treatments.
Conclusion
In summary, the elevated eye pressure of glaucoma usually causes no early symptoms and goes undetected without comprehensive eye exams. IOP is painless because the optic nerve lacks pain receptors. Additionally, glaucoma initially causes peripheral vision loss that patients fail to notice. If undetected and untreated, glaucoma progressively damages the optic nerve and results in irreversible blindness. However, early diagnosis and diligent treatment can prevent vision disability in most patients. Increased glaucoma awareness and regular ophthalmologic screening in at-risk populations allows preservation of sight through early intervention.