What is Chronic Closed Angle Glaucoma?
Glaucoma is an eye condition that develops over time, typically linked with high pressure within the eyes. It could result in complete blindness if it advances far enough. A specific type of glaucoma, called angle-closure glaucoma, happens when the area in the front part of the eye which usually helps to drain fluid becomes narrowed or blocked.
There are two types of angle-closure glaucoma – acute and chronic. Acute angle-closure glaucoma happens when there’s a blockage in that drainage area, which leads to an increase in pressure in the eye. This increased pressure can damage the optic nerve – the part of the eye that sends visual information to the brain. With chronic angle-closure glaucoma, there’s partial blockage in the drainage area which gradually causes scarring and narrowing of that area over time. As a result, fluid can’t leave the eye properly, leading to increased eye pressure.
This condition can either be primary or secondary. Primary angle-closure glaucoma exists on its own, not connected to any other eye condition or disease. Contrarily, secondary angle-closure glaucoma relates to other eye conditions. Numerous factors such as changes in the iris, trauma, and uveitis – an inflammation of the middle layer of the eye – can lead to secondary angle-closure glaucoma.
Acute angle-closure glaucoma often results in vision loss, extreme eye pain, headaches, and seeing halos around lights, along with nausea and vomiting. It needs to be treated quickly to avoid permanent loss of vision. Whereas, chronic angle-closure glaucoma can occur with or without symptoms and can potentially harm the optic nerve over time. ‘Silent’ and ‘creeping’ are other names for this condition, as it leads to a slow increase in eye pressure and creeping closure of the eye’s drainage area.
What Causes Chronic Closed Angle Glaucoma?
PAC glaucoma is a condition where the pressure in the eye increases due to a narrowing of the front part of the eye. This can cause sudden and persistent rises in the eye’s pressure. If the contact between the iris (the colored part of the eye) and the drain of the eye happens often enough, it can create a barrier that in turn leads to chronic glaucoma.
Here are different stages of this disease:
1. Primary angle-closure suspects: This is when the eye has a ‘narrow’ front part, but the eye pressure is normal and no barriers have formed.
2. Primary angle-closure: In this case, the pressure in the eye has risen or a barrier has formed, but there’s no indication of glaucoma-related damage to the optic nerve or vision.
3. Primary angle-closure glaucoma: This is when on top of increased pressure and the formation of barriers, there are also signs of damage from glaucoma that can affect the structure or function of the eye.
Several factors inside the eye can cause PAC glaucoma. For instance, the iris might lean forward and close the “drain” in the eye due to an imbalance of pressure in the eye when the flow of fluid is blocked. This is the cause of most acute PAC cases. Another issue might be related to an unusual placement of certain structures in the eye causing the iris to close the “drain”. Lastly, as we age, changes in the structure and position of the eye’s lens may play a big part in PAC.
Certain physical characteristics can increase one’s risk of getting PAC glaucoma. These could include having a small space in the front part of your eye, a thick lens, a certain curvature of the lens, a small corneal radius, or a forward-placed lens. Additionally, having frequent inflammation in the eye, a petite eye length, or a specific iris or lens condition can also increase risk factors.
Secondary causes may include inflammation of the eye (uveitis), injury to the eye, abnormal blood vessel growth in the iris, eye surgery, or unusual tissue growth following surgery.
Certain medications can also cause problems in those who are at risk. These can include some drugs for asthma and depression, steroids, and certain cold and flu medications.
Risk Factors and Frequency for Chronic Closed Angle Glaucoma
Glaucoma is one of the top causes of permanent blindness globally, coming just after cataracts. By 2040, it’s predicted that more than 110 million people worldwide will have glaucoma. In particular, a type of glaucoma known as PAC glaucoma varies considerably in how often it occurs in different groups of people. Latest research from 2021 put the global occurrence of PAC glaucoma at 0.6%, a rate that increases with age. It is most commonly found in Asian populations, where the occurrence rate is 1.1%. Studies in China suggest that most cases of PAC glaucoma are due to multiple factors; including a plateau iris, a thicker iris edge, lens moving forward, and the iris root inserting more to the front.
Primary open-angle glaucoma, a different type of the disease, is three times more common than angle-closure glaucoma. Yet, half of the blindness caused by glaucoma is due to angle closure. Angle-closure glaucoma is two to three times more common in females than males and is more common in people older than 40. It is most frequently found in Asian, African, and Inuit populations, and people with a family history of angle closure are more likely to develop it.
After the age of 40, the prevalence of PAC glaucoma and a related condition, relative pupillary block, tends to increase. Research on Europeans shows that the occurrence of PAC glaucoma is 0.02% for people aged 40 to 49, rising to 0.95% in people over 70. This is likely due to a gradual decrease in the size and depth of the anterior chamber of the eye, lens thickening as a result of cataract formation, and a progressive narrowing of the anterior chamber throughout a person’s life. PAC glaucoma is less common in younger people, but, when it does occur in them, it’s often linked to plateau iris syndrome and other eye abnormalities.
Signs and Symptoms of Chronic Closed Angle Glaucoma
Chronic angle-closure glaucoma is a condition in which the eye’s internal pressure increases due to a blockage in the drainage system. Most people with this condition don’t experience any symptoms. However, some might show symptoms due to intermittent blockages which resolve on their own.
The patient’s past medical history can hint at the possibility of chronic angle-closure glaucoma. History of eye surgery, eye trauma, repeated inflammation, sudden angle-closure glaucoma, farsightedness, or long-standing cataracts could be red flags. A family history of angle closure, diabetes, and disorders related to inflammation of the middle layer of the eye (uveitis) like rheumatoid arthritis and spondylitis could serve as indicators too. It’s also crucial to understand the patient’s medication history, as some drugs can trigger acute angle closure in susceptible people.
Acute angle-closure glaucoma shows more pronounced symptoms. These include seeing halos around lights, reduced vision sharpness, headache, severe eye pain, and episodes of nausea and vomiting. Typical signs of an acute increase in eye pressure include redness of the eye’s outer layer, cloudy or swollen corneas, an unusually shallow front part of the eye, and a moderately dilated pupil (about 4 to 6 mm) that responds poorly to light.
- Normal visual acuity might be observed
- Increase in eye pressure, usually above 21 mmHg
- Different degrees of blockages observed on an eye exam procedure called gonioscopy
- Damage to the optic nerve head
- Loss of visual field
- Thinning of the retinal nerve layers observed on an imaging test called optical coherence tomography
Testing for Chronic Closed Angle Glaucoma
The evaluation process for angle-closure glaucoma involves several important tests and examinations. These could include checking your vision acuity, pupil health, and inner eye pressure. They may also examine the front parts of your eyes with a tool called a slit-lamp, perform visual field testing, and conduct a procedure called gonioscopy. Lastly, an examination of the back part of your eye (undilated fundus examination) is required.
If you’re experiencing symptoms in one eye, though, it’s important to remember that both eyes need to be examined. Signs of previous episodes of increased intraocular pressure, which is the pressure in your eye, could include changes in your iris (the colored part of your eye), spots on the front part of your lens, or even a normal or increased intraocular pressure reading. If you have narrow-angle glaucoma, your optic disc might show a depression or “cupping”.
Gonioscopy is considered the gold standard test for diagnosing angle-closure glaucoma. This involves applying gentle pressure to the eye with a special lens during a slit lamp exam. If your angles aren’t completely closed yet due to scarring, they should widen during this procedure.
A slit-lamp biomicroscope examination of the anterior segment of the eye helps assess the depth and angle of the anterior chamber. The Van Herick score is a quick way to perform this evaluation, but it doesn’t replace gonioscopy. This technique evaluates your angle width, with higher scores indicating wider angles and less risk of angle closure.
Another important test is tonometry, which measures intraocular pressure, a crucial factor in diagnosing and managing all types of glaucoma. In the exam, your healthcare provider will press a small tool onto your eye to measure your eye’s pressure. The thickness of the cornea is also important in interpreting tonometry readings. Pachymetry measures corneal thickness to give useful context to tonometry readings.
Examining the optic nerve head is also required. Avoiding examinations using a dilated pupil is recommended as it can exacerbate the condition. The optic nerve often shows cupping or a hollow appearance in glaucoma patients during fundus examination. Changes in the cup’s size or shape, and asymmetry between the eyes also suggest glaucoma.
Visual field analysis helps identify and evaluate the functional damage caused by glaucoma. In some cases, automated tests are more reliable than manual tests, but manual tests can be helpful for certain patients.
Technology like Optical Coherence Tomography and Ultrasound Biomicroscopy provides a detailed image of your eyes and may be used to further evaluate the situation. However, these tests are often costly and not widely available.
While some other tests, like pharmacological provocation tests and darkroom-prone provocation tests, can be used, they may not be very helpful in identifying glaucoma. In fact, some tests might carry unnecessary risks for patient. Furthermore, a negative result doesn’t mean you can rule out the diagnosis of glaucoma.
Treatment Options for Chronic Closed Angle Glaucoma
The first treatment for chronic angle-closure glaucoma typically involves using a specific type of laser to alleviate any blockage in the eye. If the eye pressure remains too high, medication is then introduced.
The treatment can work in two ways. One is to reduce the production of a fluid called aqueous humor, and this can be achieved through medications. Examples include dorzolamide, brinzolamide, acetazolamide, methazolamide (all carbonic anhydrase inhibitors), brimonidine tartrate and apraclonidine (alpha-adrenergic agonists), and timolol and levobunolol (beta blockers).
The other way treatment works is by increasing the outflow of the aqueous humor, which can be achieved by medications like latanoprost, travoprost, and bimatoprost (topical prostaglandins), along with alpha-adrenergic and cholinergic agonists, and rho kinase inhibitors. However, medicines that increase the fluid outflow may not work as effectively if the eye’s meshwork is blocked.
Prostaglandins, which have fewer side effects compared to beta blockers, are often the prefered medication for treatment. But some side effects can include redness, eye irritation, changes in lash and iris color, and increase in number and length of eyelashes. Adverse effects of beta blockers can include worsening heart failure, slow heart rate, heart block, increased airway resistance, intolerance to exercise, depression, and sexual dysfunction. It’s also important to know that in many cases, more than one medication may be necessary to control eye pressure.
In terms of surgical treatment, one method includes something called trabeculectomy, but this increases the risk of further complications and may require the patient to undergo more medications to control eye pressure. Another surgical method is lens extraction, which can expand the drainage angle but could increase complications and necessitate further surgery. Goniosynechialysis is a method that helps restore fluid access to the eye’s meshwork and is prefered in cases with minimal to moderate nerve damage. Other advanced methods involve use of lasers or implants. However, these techniques are only considered in complicated cases or where prior treatments have been unsuccessful.
What else can Chronic Closed Angle Glaucoma be?
Doctors need to tell the difference between chronic angle-closure glaucoma and open-angle glaucoma, as well as other conditions that could be harming the optic nerve (the part of the eye that sends visual information to the brain). These conditions could include those caused by restricted blood supply, pressure on the nerve, or inherited diseases.
Additional conditions they need to consider could include:
- Inflammation inside the eye (iritis)
- Bleeding in the eye caused by injury (traumatic hyphema)
- Red, irritated, or watery eyes (conjunctivitis)
- Inflammation of the white part of the eye (episcleritis)
- Bleeding under the covering of the eye (subconjunctival hemorrhage)
- Scratch on the front part of the eye (corneal abrasion)
- Infection of the cornea (infectious keratitis)
What to expect with Chronic Closed Angle Glaucoma
The outlook for chronic angle-closure glaucoma can be positive if eye pressure is effectively managed. Yet, elements like the stage of the disease, changes in eye pressure, and a thinner central cornea can lead to the disease getting worse over time. A more significant presence of certain eye conditions and a smaller drainage angle could also cause higher eye pressures and a larger vertical eye cup-related measure, which could suggest damage due to glaucoma.
In a study featuring Chinese patients, poorer vision and clarity outcomes were reported, with 7% advancing to blindness despite treatment over a decade. It’s crucial to note that performing preventive eye procedures does not assure the avoidance of angle-closure glaucoma. Interestingly, 50% of the eyes that underwent a preventive procedure during an angle closure in the opposite eye still developed chronic angle-closure glaucoma.
Possible Complications When Diagnosed with Chronic Closed Angle Glaucoma
Glaucoma can cause permanent harm to the optic nerve. This can result in a variety of complications including loss of visual field (area in which objects can be seen), reduced sharpness of vision, total blindness, damage to the inner layer of the cornea leading to corneal decompensation (swelling and clouding), and aqueous misdirection syndrome (a rare form of glaucoma).
Additionally, there are also potential complications related to surgery for glaucoma. These may include further narrowing of the eye’s front chamber, development of malignant glaucoma (a serious form of glaucoma), advancement of cataracts, irreversible harm to the “meshwork” (the tube-like structure in the eye that drains fluid), and growth of iris or fibrous tissue in the space within the trabecular meshwork (drainage pathway).
- Loss of visual field
- Decreased visual acuity (sharpness)
- Total blindness
- Corneal decompensation (swelling and clouding)
- Aqueous misdirection syndrome
- Narrowing of the eye’s anterior chamber
- Malignant glaucoma
- Progression of cataracts
- Damage to the trabecular meshwork
- Growth of iris or fibrous tissue in the eye
Preventing Chronic Closed Angle Glaucoma
Angle-closure glaucoma is a type of eye disorder that happens when the drainage part in the front of the eye becomes narrowed or blocked. This reduces the flow of the fluid (aqueous humor) that fills the eye, increasing the pressure inside the eye. High pressure can cause harm to the optic nerve, which helps us see. If left unnoticed or untreated, this form of glaucoma can cause vision loss or even blindness.
The blockage in the drainage part can occur naturally due to a person’s body shape or structure. Or, it can be caused by an underlying sickness or structural issue in the eye. The people most at risk of getting angle-closure glaucoma are older women, people over 60 with a family history of the condition, and those of Asian, Inuit, or African origin. Some common over-the-counter medicines, such as some cold and cough medicines, allergy medications, and certain other drugs, can also increase the risk for people prone to this condition. If a person knows they have narrow eye angles but haven’t yet started treatment, they should refrain from these medicines.
People with a background of PAC (Primary angle-closure) glaucoma in their families should have regular eye checks, particularly as they reach their 40s and 50s. There’s a test called gonioscopy used to examine the angles of your eye. And a treatment called laser peripheral iridotomy can be used for angle-closure glaucoma. If the eye pressure doesn’t come down to normal after surgery, the patient may need to take medication to help reduce it further.
