Closed angle glaucoma or Angle-closure glaucoma
Definition:
Closed-angle glaucoma is a type of glaucoma and occurs due to rapid or sudden rise of intraocular pressure. Closed-angle glaucoma is a less common form of glaucoma as compared to open-angle glaucoma.
It occurs when the iris bulges forward and blocks the drainage angle formed by the cornea and iris. This restricts the circulation of fluid out of the eye and results in increase of IOL pressure.
Types of Closed-Angle Glaucoma
Closed-angle glaucoma is of following two main types:
Primary Closed-Angle Glaucoma: It occurs without any underlying disease, basically due to the structural abnormality that presses the iris against the trabecular meshwork. Structural abnormality may include any of the following:
- Very narrow angle between the iris and cornea
- Short eyeball
- Thick lens
- Thin iris
Secondary Closed-Angle Glaucoma: It occurs due to the changes caused by an underlying condition that force the iris against the trabecular meshwork. The underlying conditions may include any of the following:
- Eye injury
- Eye inflammation
- Systemic conditions like diabetes, tumor etc.
- Advanced cataract
Closed-angle glaucoma can also be described as acute or chronic depending upon the attack of eye disease.
Acute closed-angle glaucoma occurs suddenly and is more common. It can be triggered due to sudden dilation of pupils and is a medical emergency.
Chronic closed-angle glaucoma is harder to notice as it develops gradually.
Risk factors for Closed-Angle Glaucoma
Individuals with following conditions are at higher risk of developing closed-angle glaucoma:
- Age above 40 years (especially between 60 and 70 years)
- Far-sightedness or hyperopia
- Females
- Family history
- Certain races (for example, Asians and Eskimos)
- Narrow drainage angles
- Diabetes
Symptoms of Closed-Angle Glaucoma
Symptoms depend upon acute or chronic stage of the glaucoma and may occur when pupils are moderately dilated (especially in a darkened room, under stress, or after taking certain drugs).
In acute stage, person will experience a sudden onset of one or more of the following symptoms in only one eye:
- Sudden & severe eye pain & tenderness
- Headache
- Blurred vision
- Bright halos appearing around objects
- Profuse tearing
- Eye redness
- Eye hardness
- Nausea and vomiting
- Symptoms worsen over a few hours
In chronic closed-angle glaucoma, the symptoms are subtler, but not as severely as in acute closed-angle glaucoma and may include the following:
- Deterioration of eye sight
- Loss of the vision in edges
- Eye pain and redness
Diagnosis of Closed-Angle Glaucoma
Early diagnosis of any kind of glaucoma plays the most important role in vision prevention. Diagnosis of glaucoma involves thorough eye examination and following tests:
- Gonioscopy to examine the drainage angle of the eye
- Tonometry to measure the pressure inside the eye
- Bio-microscopy to examine the front of the eyes
- Ophthalmoscopy to examine the optic nerves for any damage or abnormalities
Treating Closed-Angle Glaucoma
It is an emergency condition that needs to be managed immediately to prevent vision loss or preserve some vision. Although there is no curative treatment for closed-angle glaucoma but following forms the emergency line of treatment to preserve as much vision as possible:
- Medications: Various medications are prescribed by an ophthalmologist to lower the raised IOP. These may include:
- Eye drops like acetazolamide, beta blockers, steroids, pilocarpine etc.
- Oral medications (osmotic agents such as glycerol or carbonic anhydrase inhibitors such as Diamox)
- Intravenous medication (mannitol)
- Surgical intervention: Surgery is the main treatment of closed-angle glaucoma but can only be performed if IOP has been lowered by medication. The following surgeries are performed to address closed-angle glaucoma:
- Peripheral Iridotomy (Laser therapy)
- Laser Gonioplasty
- Surgical Iridectomy (Incisional surgical therapy)
