Glaucoma

What is glaucoma?

Glaucoma refers to a group of disorders that lead to damage to the optic nerve, the nerve that carries visual information from the eye to the brain. Damage to the optic nerve causes vision loss, which may progress to blindness. Most people with glaucoma have increased fluid pressure in the eye, a condition known as increased intraocular pressure.

What are the types of glaucoma?

  • Open angle (chronic) glaucoma
  • Angle closure (acute) glaucoma
  • Congenital glaucoma
  • Secondary glaucoma

What causes glaucoma?

The eye constantly produces aqueous, the clear fluid that fills the anterior chamber (the space between the cornea and iris). The aqueous filters out of the anterior chamber through a complex drainage system. The delicate balance between the production and drainage of aqueous determines the eye’s intraocular pressure (IOP). Most people’s IOPs fall between 8 and 21. All four types of glaucoma are characterized by increased pressure within the eyeball, and therefore all can cause progressive damage to the optic nerve.

Open angle(chronic) glaucoma ( most common)-The front part of the eye is filled with a clear fluid called the aqueous humor. This fluid is constantly made in the back of the eye. It leaves the eye through channels in the anterior (front) chamber of the eye, and eventually drains into the bloodstream. The channels that drain the aqueous humor are in an area called the anterior chamber angle, or simply the angle.In this, the channels in the angle gradually narrow with time, making it hard for the fluid to drain properly. The buildup of fluid causes increased pressure in the eye. This increased pressure pushes on the junction of the optic nerve and the retina at the back of the eye, reducing the blood supply to the optic nerve. Peripheral (side) vision is affected first. This is usually not noticed until quite a bit of vision is lost. If the disease is not diagnosed and treated, a lot of vision may be lost before the person becomes aware of a problem.There may be redness and swelling in the affected eye. Nausea and vomiting may occur. Angle closure glaucoma is an emergency. This is very different from open angle glaucoma, which painlessly and slowly damages vision.

If you have had acute glaucoma in one eye, you are almost certainly at risk for an attack in the second eye, and your doctor is likely to recommend preventive treatment.Dilating eye drops and certain systemic medications may trigger an acute glaucoma attack if you are at risk.

Secondary glaucoma is caused by other diseases, including eye diseases such as uveitis, systemic diseases, and drugs such as corticosteroids.

Congenital glaucoma, which is present at birth, is the result of abnormal development of the fluid outflow channels of the eye. Surgery is required for correction. Congenital glaucoma is often hereditary.

What are the symptoms of glaucoma

Open angle glaucoma-Most people have no symptoms but gradual loss of peripheral (side) vision may occur.

Acute angle glaucoma-Severe eye pain, facial pain ,decreased or cloudy vision, redness and swelling of the eye,nausea and vomiting .

Congenital glaucoma-Tearing ,sensitivity to light, redness and cloudiness of the front of the eye.

What type of exam and test need to detect glaucoma?

An examination of the eye may be used to diagnose glaucoma along with measurement of intraocular pressure. Tests may include:

  • Retinal examination
  • Intraocular pressure measurement by tonometry
  • Visual field measurement
  • Visual acuity
  • Refraction
  • Pupillary reflex response
  • Slit lamp examination
  • Optic nerve imaging (photographs of the interior of the eye)
  • Gonioscopy- use of a special lens to see the outflow channels of the angle

How glaucoma will be treated?

The objective of treatment is to reduce intraocular pressure. Depending on the type of glaucoma, this is achieved by medications or by surgery.

Open angle glaucoma treatment:
  • Most people with glaucoma can be treated successfully with eye drops and pills to lower pressure in the eye.
  • Some patients will need additional forms of treatment, such as a laser treatment, to help open the fluid outflow channels. This procedure is usually painless. Others may need traditional surgery to open a new outflow channel.

Angle closure glaucoma treatment:

Acute angle closure attack is a medical emergency. Blindness will occur in a few days if it is not treated. Drops, pills, and medicine given by intravenous route are used to lower pressure. The patient may also need an emergency operation, called an iridotomy which uses laser to open a new channel in the iris which relieves pressure and prevents another attack.

Congenital glaucoma: This form of glaucoma is almost always treated with surgery to open the outflow channels of the angle.

What are prognosis?

Open angle glaucoma: It can be managed and vision will almost always be preserved, but the condition cannot be cured. Careful follow up with doctor is important. With good care, most patients with open angle glaucoma will not lose vision.

Angle closure glaucoma: Rapid diagnosis and treatment of an attack is the key element to preserve vision.

congenital glaucoma: Early diagnosis and treatment is important. If surgery is done early enough, many patients will have no future problems.

When to contact a doctor?

Consult doctor if you have severe eye pain or a sudden loss of vision, especially loss of peripheral vision.

Can glaucoma be prevented?

  • There is no way to prevent glaucoma, but vision loss can be prevented with early diagnosis and careful management of the condition. All persons over 40 years should have an eye examination at least every 5 years, and more often if in a high-risk group.
  • People at high risk for acute glaucoma may opt to undergo iridotomy before having an attack. Patients who have had an acute episode in the past may undergo the procedure to prevent recurrence.